Commissioning Systems, Batteries and Battery Charger

Note: The source of the technical material in this volume is the ProfessionalEngineering Development Program (PEDP) of Engineering Services.

Warning: The material contained in this document was developed for SaudiAramco and is intended for the exclusive use of Saudi Aramco’semployees. Any material contained in this document which is notalready in the public domain may not be copied, reproduced, sold, given,or disclosed to third parties, or otherwise used in whole, or in part,without the written permission of the Vice President, EngineeringServices, Saudi Aramco.

Chapter : Electrical For additional information on this subject, contactFile Reference: EEX30105 W. A. Roussel on 874-1320

Engineering EncyclopediaSaudi Aramco DeskTop Standards

Commissioning BatteriesAnd Battery Charger Systems

Engineering Encyclopedia Electrical

Commissioning Batteries and Battery Charger Systems

Saudi Aramco DeskTop Standards

Contents Page

Saudi Aramco Applications And Requirements For Batteries

And Battery Charger System............................................................................ 1

Evaluating Battery And Battery Charger Systems Upon Receipt .................... 36

Evaluating Battery And Battery Charger Installation And Testing ................... 38

Battery And Battery Charger System Operational Testing Requirements ....... 43

Requirements For The System Operational Observation Phase .................... 45

Summary ......................................................................................................... 46

Work Aid

Work Aid 1: References For Evaluating Batteries And Battery

Chargers Upon Receipt .................................................................................. 47

Work Aid 2: References For Evaluating Batteries And Battery

Charger Installation And Testing..................................................................... 58

Glossary .......................................................................................................... 61



Saudi Aramco DeskTop Standards 1

SAUDI ARAMCO APPLICATIONS AND REQUIREMENTS FOR BATTERIES ANDBATTERY CHARGER SYSTEMS

The type and size of batteries and battery chargers that are used in Saudi Aramco installationsare selected through use of a number of factors, such as the connected load, criticality of theload, and ambient conditions. Details of the selection process for batteries are provided inEEX 211. This Module will not deal with the actual selection process that occurred early inthe project. This Module will be concerned with the specific items that should be verified andtested during the commissioning process. Batteries and battery chargers must meet all SaudiAramco requirements before they are put into service.

Batteries

An electric cell is a device that directly converts the chemical energy that is contained inactive materials into electrical energy through use of an oxidation-reduction electrochemicalreaction. A battery is formed through the interconnection of one or more cells. These cellsmay be connected in series, which increases the voltage of the battery by the product of thecell voltage times the number of cells; or these cells may be connected in parallel, whichincreases the amount of current that is available. The available amp-hours are equal to thecell amp-hour rating times the number of cells.

Batteries are a source of alternate energy for emergency and standby systems. Batteries maybe used to power dc loads, (such as alarm and security systems) directly, or they may be usedas control power for switchgear, telephone systems, and emergency lighting. Batteries alsomay be used indirectly to provide power through rotary or static uninterruptable powersystems, which, in turn, provide power for ac loads. Batteries may also be used indirectly toprovide power for lighting and industrial processes or through standby inverters.

Generally, there are two types of batteries that are selected for emergency or standby service:lead-acid and nickel cadmium (Ni-Cad). The sealed lead-acid battery, also referred to as amaintenance-free battery, is a relatively new type of lead-acid battery that is sometimesspecified for use in Saudi Aramco facilities. (As the text below explains, seven other types oflead-acid batteries are also used.) The specific type of battery that is selected is a result of theevaluation of many factors, such as projected lifetime, ambient conditions, criticality of load,and economics. Ni-Cad batteries are more expensive than lead-acid batteries, but they aremore rugged, they require less maintenance, and they exhibit longer life than lead-acidbatteries. The actual process of battery selection is outside the scope of this course, but theinformation can be found in the Saudi Aramco text, EEX 211, Introduction to DC/UPSSystems.




Lead-Acid Batteries

The lead-acid battery is perhaps the most common type of battery that is used in industry tosupply dc loads. The lead-acid battery consists of a group of electrochemical cells that areconnected in series to generate a nominal dc voltage that is used to supply current to aspecified load. The nominal voltage of the battery is determined by the total number of cellsthat are connected in series. The amount of active material that is contained in an individualcell is the factor that determines the discharge capacity rating of the cell. The rated capacityof the individual cells is the rated capacity of the entire battery. Although the individual cellsare connected in series, the capacity amp-hour rating of the battery does not increase.

The actual chemical reaction that produces a direct current is obtained through placement of alead active material in a dilute sulfuric acid electrolyte. This electrochemical couple producesa nominal cell voltage of approximately two volts.

All lead-acid cells are constructed of the following basic components that are shown in Figure1:

• Element• Cell jar• Cell cover• Electrolyte• High and low electrolyte levels




Basic Components of a Lead-Acid CellFigure 1




Figure 2 shows an exploded view of the battery element. The battery element is the keycomponent of the cell, and it consists of an assembly of positive and negative plates that areinsulated from each other through use of separators. The interaction that occurs between thebattery element and the electrolyte determines the cell's performance characteristics.

Each of the plates consists of a rigid lead alloy that provides physical support for therelatively porous active materials. The positive and the negative plates are sandwichedtogether in an alternating pattern (e.g., negative-positive-negative-positive-negative); anegative plate is placed at each end of the assembly. Each positive plate is separated from itsneighboring negative plate through use of an insulating material. The insulating materialtypically is a thin sheet of microporous rubber or plastic that is ribbed on the side that facesthe positive plate. The positive and negative terminal posts are connected to the positive andnegative plates, respectively.

Battery ElementFigure 2




The cell jar, which was shown in Figure 1, is usually made of a transparent, impact-resistantplastic material. The cell jar must be large enough to enclose the element, yet it must stillprovide sufficient reservoir space above and below the element. The upper reservoir space isneeded to allow for the gradual lowering of the electrolyte level that occurs during normaloperation of the battery. The lower reservoir space serves as a collection basin for thesediment that is shed from the plates during the expected life of the battery. This sedimentmust be kept away from the element to prevent a short circuit between the positive and thenegative plates.

After the element has been lowered into the empty jar, the cell cover is placed over the top ofthe jar and is sealed. The terminal posts that are connected to the element protrude throughholes that are located in the top of the cell cover. The cell cover also is fitted with a flamearrestor vent that allows gases to escape from inside of the cell but that prevents entry ofsparks or flames.

The electrolyte that is used in lead-acid batteries is a dilute solution of sulfuric acid and water.The ratio of acid weight to water is measured as specific gravity. Pure water has a specificgravity of 1.000. A typical, nominal specific gravity for a lead-acid storage battery is 1.215 at25°C (77°F). The specific gravity of the electrolyte gradually drops as the cell is discharged.When the battery charger recharges the cell, the specific gravity gradually rises back to thenominal value.

If a battery is to be operated at temperatures that exceed 29_C (85_F) for more than 30 daysper year, a tropical (low) specific gravity electrolyte could be used to increase the life of thebattery. A medium or a high specific gravity electrolyte is also available for specialapplications, such as UPS systems, that, in some cases, will reduce the overall battery size thatis required.

As previously stated, all lead-acid batteries contain the same basic components. The majordifference between the various types of lead-acid batteries is the design of the positive platesthat are used in the battery element. The remainder of this section provides information onthe following specific types of lead-acid batteries:

• Plante• Lead calcium• Lead antimony• Sealed (Maintenance-Free)

Plante - The plante lead-acid battery is a lead-acid storage battery in which the active materialof the positive plates is electrochemically developed from pure metallic lead. Modern Plantelead-acid batteries are available with two types of positive plate constructions: traditional andManchester. Both types of plates are shown in Figure3.




The traditional positive plate starts off as a blank (slab) of pure metallic lead. Grooves arethen cut into the surface of the lead blank through use of a combing process. The groovesincrease the surface area of the plate, which increases the capacity of the cell.

The Manchester plate is the most common type of plate that is used in Plante lead-acidbatteries. The Manchester plate is constructed of a heavy antimony alloy grid that is cast withcircular holes. Heavy corrugated strips of high purity lead are then rolled into spiral buttonsor "rosettes" that are forced into the holes that are cast in the grid. Each of the lead buttonsexposes approximately five times more surface area to the electrolyte than a comparable areaon a pasted plate battery. The lead buttons also help to prolong the life of the cell byproviding a reserve supply of unformed lead that is gradually converted to active materialduring operation of the cell.

The negative plates of Plante lead-acid batteries are pasted or "flat" plates with a heavy alloygrid. The construction of these plates will be discussed in more detail in the next section ofthis Module.




Positive Plates Used in Plante Lead-Acid BatteriesFigure 3

The following are the major advantages and disadvantages of Plante lead-acid batteries:

Advantages Disadvantages• Long service life (20 to 25 years). • High cost.• Smallest amount of positive plate

growth of all lead-acid cells.• Poor energy density and poor

power density.• Very high reliability. • Moderate self-discharge rates

(3%/month).




Plante lead-acid batteries have the highest capital cost of all types of lead-acid batteries. Thecost of Plante lead-acid cells is approximately 3 to 3-1/2 times that of a comparable leadantimony cell and approximately 2-1/2 to 3 times that of a comparable lead calcium cell.However, in some applications, the high initial capital cost may be justified by the long (25year) service life.

The cyclic performance and cycle life of Plante lead-acid batteries, as is the case with allstationary lead-acid storage batteries, can only be discussed in relative terms. Stationary lead-acid storage batteries are designed to provide a relatively long calendar service life (more thanten years) when they are operated under float charge conditions rather than a long cycle life.Stationary lead-acid storage batteries are normally not rated or guaranteed to deliver a specificnumber of equivalent full charge cycles.

When any stationary lead-acid storage battery is subjected to deep and frequent discharges, itscalendar service life will be reduced; however, because of the number of variables that areinvolved, the specific amount of calendar service life reduction cannot easily be quantified.For this reason, the cyclic performance of one type of lead-acid storage battery is generallyonly discussed in terms of comparison with another type of stationary lead-acid storagebattery.

The cyclic performance (e.g., the ability to withstand frequent and/or deep discharges) ofPlante lead-acid batteries is far superior to the cyclic performance of lead calcium batteriesand is approximately equivalent to the cyclic performance of lead antimony batteries. Plantelead-acid batteries are capable of withstanding a moderate amount of cycling with a minimumloss of calendar service life.

Lead Calcium - The positive and the negative plates of lead calcium batteries are pasted plates.Pasted plates are constructed by forcing a thick slurry of active material (e.g., a combinationof lead oxides and sulfuric acid) into an open lattice grid. A typical pasted plate grid is shownin Figure 4. The open lattice grid is cast from an alloy of pure lead and calcium. The additionof the calcium alloying agent is necessary to increase the mechanical strength of the plate.




Typical Pasted Plate GridFigure 4

After the active material is pasted on the open lattice grid, the plates are dried and formed(activated) by an electrochemical process. The completed plate is porous so that the sulfuricacid electrolyte can circulate through the active material. The porous construction greatlyincreases the surface area of active material that is in contact with the electrolyte, whichincreases the capacity of a given sized cell.

The following are the major advantages and disadvantages of lead calcium batteries:

Advantages Disadvantages

• Medium service life (12-15 years) • Subject to excessive positive plate gridgrowth.

• Better energy density and power • Not suitable for deep or frequent




density than Plante batteries. discharges.

• Low self-discharge rates (1%/month)

• Low water consumption

• Medium cost

The cost of lead calcium batteries is more than the cost of lead antimony batteries but isconsiderably less than the cost of Plante batteries. On a cursory examination, this mediumrange cost, when coupled with the other advantages of lead calcium batteries, makes thisbattery appear to be more attractive for most applications than the Plante battery. However, acloser look at the disadvantages of the lead calcium battery shows that this battery is onlymore attractive in non-cycling applications.

The cyclic performance of lead calcium batteries is extremely poor. Of the three major typesof stationary lead-acid storage batteries (Plante, lead calcium, and lead antimony), the leadcalcium battery suffers the greatest loss of calendar service life when it is subjected to cyclicservice. Lead calcium batteries should only be used in float charge, shallow-cycleapplications.

Lead Antimony - The positive and the negative plates of lead antimony batteries are also pastedplates. The only difference between the construction of lead antimony batteries and theconstruction of lead calcium batteries is the addition of an antimony alloying material to thegrid rather than a calcium alloying material. The antimony alloying material, which is similarto the calcium alloying material, is added to increase the mechanical strength of the plate.

The amount of antimony that is used in the grid varies by weight from about 1.5% to 12%antimony. The percentage of antimony that is used affects the characteristics of the battery.High antimony content provides greater grid strength; however, it also results in higher floatcurrent requirements, an increase in water usage, and an increase in the frequency ofequalizing charges towards the end of the battery's service life. Low antimony contentprovides more desirable operating characteristics but at the sacrifice of grid strength. If theantimony content is less than 4%, small amounts of other elements, such as selenium, must beadded to maintain sufficient grid strength. Saudi Aramco does not allow the use of leadantimony batteries that contain more than 3% antimony.

The following are the major advantages and disadvantages of lead antimony batteries:

Advantages Disadvantages• Low cost. • High self-discharge rates

(7%/month).




• Better energy density and power density than Plante batteries.

• Short service life (10-12 years).• High water consumption

• Can be used in cycling service.

Lead antimony batteries have the least capital cost of all lead-acid batteries. The low capitalcost makes this battery an attractive choice for cycling service applications in which the highwater usage is acceptable.

The cyclic performance of lead antimony batteries is approximately equivalent to the cyclicperformance of Plante batteries. Lead antimony batteries can withstand a moderate amount ofcycling with a minimum loss of calendar service life.

Sealed (Maintenance-Free) - Two different versions of sealed (maintenance-free) lead-acidbatteries are available: the gelled electrolyte version and the absorbed glass mat (AGM)version. The basic technology of both versions of sealed lead-acid batteries is identical in thatthey are both recombinant-type batteries. Recombinant-type batteries have positive limitedplate groups that operate on an oxygen cycle.

During battery recharge, oxygen is released at the positive plate, and, when the negative plateis fully charged, it releases hydrogen. These gases are formed from the decomposition of thewater that is in the electrolyte. Because of the explosive nature of hydrogen, the gases mustbe vented out of the battery room, and they must be properly dispersed. In flooded lead-acidbatteries, this electrolyte water loss must be replaced on a regular basis to prevent the batteryplates from drying out.

In sealed lead-acid batteries, the negative plate is designed to be what is known in the industryas "positive limited" because the battery discharge chemical reaction is stopped when thepositive plate is exhausted. When a sealed lead-acid battery is recharged, the negative platenever reaches its full charge condition; therefore, hydrogen gas is not released. The oxygen isreleased at the positive plate, and it travels to the negative plate through the void paths that arein the plate separator. At the negative plate, the oxygen combines with the lead in thenegative plate to form lead dioxide. The lead dioxide reacts with the sulfuric acid that is inthe electrolyte to form lead sulfate and water. The water that is created replaces the water thatwas consumed at the positive plate to make the oxygen; therefore, water never needs to beadded to the battery, and the battery case can be sealed to prevent evaporation.

The oxygen that is generated at the positive plate creates a positive pressure inside the batterythat is two to three pounds above the ambient pressure. Because of this positive pressure,sealed lead-acid batteries must contain a relief valve to prevent overpressurization of the




battery in the event of a malfunction, such as a runaway charger. The relief valves aredesigned to automatically reseal once the pressure returns to normal.

The following are the major advantages and disadvantages of sealed lead-acidbatteries:

Advantages Disadvantages• Long service life (15 to 20 years) in

float service.• No maintenance.

• High cost.• Short service life (< 10 years) in

cyclingservice

• Reduced battery room/ventilation • Moderate self-discharge rates(3%/month).

requirements• Vertical or horizontal mounting.

• Not suitable for deep or frequentdischarges.

The development of sealed lead-acid batteries for large stationary storage applications is arelatively recent (within the last ten years) technology and, as such, these batteries are moreexpensive than their lead calcium and lead antimony flooded cell counterparts. The cost ofsealed lead-acid batteries is similar to the cost of Plante lead-acid batteries. Plante lead-acidbatteries are described later in the Module. Sealed lead-acid batteries do not perform well infrequent or deep-cycle applications, and they should only be used in float charge, shallow-cycle applications.

Nickel Cadmium (Ni-Cad)

Nickel cadmium (Ni-Cad) cells may be either sealed or vented. Some of the sealed-typeincorporate a high-pressure vent as a safety measure. The vent would relieve at 100 to 300psig. Sealed Ni-Cad battery cells are designed for applications that are lightweight andportable, and they provide a long operating life. These types of cells are generally used forsmall portable electrical equipment that operates on a dc source. The vented-type of Ni-Cadcell is used for emergency and standby service.

The Ni-Cad cell provides a high discharge rate. Ni-Cad batteries also provide a fast rechargefor emergency engine starting and for standby service. When compared to a lead-acid cell,the Ni-Cad cell is generally smaller and lighter, and it requires less maintenance than lead-acid cells. If the cell is overcharged, the resealable vent allows hydrogen and oxygen gasesthat are generated by the electrolysis of water to escape to the atmosphere. The vent isolatesthe electrolyte so that it cannot pick up carbon dioxide from the atmosphere and becomecarbonated. As a result, deionized water must be added at regular intervals.

The Ni-Cad battery also consists of a group of electrochemical cells that are connected inseries to generate a nominal dc voltage that would supply power to a suitably connectedelectrical load. The number of cells that are connected in series determines the nominalvoltage rating of the battery.




The electrochemical couple that is used to form Ni-Cad cells is configured through placementof a nickel hydroxide positive electrode and a metallic cadmium negative electrode in a dilutepotassium hydroxide electrolyte. This electrochemical couple produces a nominal cellvoltage of approximately 1.2 volts.

The following types of Ni-Cad stationary storage batteries will be discussed in this section:

• Pocket-Plate• Sintered-Plate

Pocket-Plate - Pocket-plate Ni-Cad batteries get their name from the "pocket" strip that holdsthe active material of the plates. The pockets are made from very thin, finely perforated stripsof steel that are formed into shallow "U" channels, as shown in Figure 5. The positive activematerial, which consists of hydrates of nickel oxide and graphite, and the negative activematerial, which consists of cadmium oxide and a small amount of iron oxide, are placed intothe open "U" channel. The open "U" channel is then covered with a similar strip of perforatedsteel, and the two strips are crimped together to form a perforated pocket.

A number of these perforated pockets are interlocked edge-to-edge and then cut to theapproximate finished plate width. The interlocked pockets are then rolled to compress theactive material and to form longitudinal indentations in the plate. Each plate group is thenbolted or welded together. The two (positive and negative) plate groups are interleaved andinsulated with plastic rod or mat separators that are inserted into the longitudinal grooves ofthe plates. The insulated plate group or element is then inserted into a plastic container or jar.After the mechanical assembly is complete, the cells are put through an electrochemicalformation process to convert the active materials to their charged condition.




Pocket-Plate ConstructionFigure 5

Figure 6 shows a cut-away view of a typical pocket-plate Ni-Cad battery. The followingcomponents are identified in Figure 6:

• Vent Cap/Flame Arrestor• Cell Container or Jar• Plate Tab• Plate Group Bus• Separating Grids• Plate Frame• Plate




Typical Pocket-Plate Ni-Cad BatteryFigure 6




The vent cap/flame arrestor allows the gases that are generated during normal charging anddischarging to escape from the battery, but it prevents the entry of sparks and foreignmaterial. The vent cap/flame arrestor can be removed to allow access to the interior of thecell.

The cell container or jar is constructed of translucent polypropylene. The cell container or jaris the enclosure that holds the individual components of the cell and that contains the liquidpotassium hydroxide (KOH) electrolyte.

The plate tabs are spot welded to the plate frame and to the upper edge or the pocket plates.The plate tabs provide the electrical connection between the plates and the plate group bus.The plate group bus connects the plate tabs to the terminal posts of the battery.

The plate tabs and the terminal posts are welded to opposite sides of the plate group bus.

The separating grids separate the plates and insulate the plate frames from each other. Theseparating grids are porous, and they allow the free circulation of the KOH electrolytebetween the plates.

The plate frames seal the plate pockets, and they serve as current collectors. The plates inFigure 6 have horizontal pockets of double-perforated steel strips.

Most manufacturers make three general pocket-plate designs: thin plates, medium plates, andthick plates. The thin-plate design has a low internal resistance, and it is used in high rate,short duration (less than 30 minutes) discharge cells. The medium-plate design has aninternal resistance that is similar to the internal resistance of general purpose lead-acid cells.This plate design is used in median rate, median duration (from 30 minutes to 2 hours)discharge cells.

The thick-plate design has a high internal resistance, and it is used in very low rate, longduration (more than two hours) discharge cells.

All vented Ni-Cad batteries have several general advantages over their flooded lead-acidcounterparts. One of these advantages stems from the KOH electrolyte that is used in Ni-Cadbatteries. The freezing point of the KOH electrolyte with a typical specific gravity of 1.190 is-32°C (-25°F). Because the specific gravity of the electrolyte in a Ni-Cad battery remainsrelatively constant from the fully-charged state to the fully-discharged state, the freezing pointalso remains relatively constant. In contrast, the freezing point of a fully-discharged lead-acidbattery is essentially the same as the freezing point of water or 0°C (32°F); therefore, lead-acid batteries are much more likely to freeze than Ni-Cad batteries. Ni-Cad batteries alsomake a significantly higher percentage of their current available at lower temperatures thanlead-acid batteries.




Another general advantage of Ni-Cad batteries is that they require much less maintenancethan flooded lead-acid batteries. Ni-Cad batteries can last years without being watered, andthey will not deteriorate when they are left in a discharged condition. Ni-Cad batteries havebeen successfully returned to service after being left "on-the-shelf" for 10 to 15 years.

The other general advantages of Ni-Cad batteries include a more rugged and durableconstruction (i.e., relatively immune to vibration, shock, and overcharge currents), a longcycle life, and minimal gas generation on charge and discharge. Also, the gaseous vapors thatare emitted from Ni-Cad batteries are not corrosive to ferrous metals.

The only general disadvantage of Ni-Cad batteries as compared to flooded lead-acid batteriesis the high cost of Ni-Cad batteries. The cost (dollars/kilowatt-hour) of Ni-Cad batteries isfour to ten times the cost of flooded lead-acid batteries. Because cadmium is also moredifficult and expensive to recycle or dispose of than lead, the disposal cost of expended Ni-Cad batteries is higher than the disposal cost for expended lead-acid batteries. In NorthAmerica, large Ni-Cad storage batteries are being phased out of production as a result of thedisposal issues that surround cadmium.

The advantages of pocket-plate Ni-Cad batteries over sintered-plate Ni-Cad batteries are thatpocket-plate Ni-Cad batteries have a lower cost and a longer cycle life, and they do not suffera "memory" effect on shallow discharges. The major disadvantage of pocket-plate Ni-Cadbatteries is that they only have about 50% of the energy density of sintered-plate Ni-Cadbatteries.

In contrast to flooded stationary lead-acid batteries, pocket-plate Ni-Cad batteries have a longcycle life in addition to a long calendar life. Under normal operating conditions, pocket-plateNi-Cad batteries can deliver as many as 2,000 equivalent full-charge cycles. The calendar lifeof pocket-plate Ni-Cad batteries ranges from 15 to 25 years. Because of the large number ofcycles that this battery can withstand (more than 80 equivalent full-charge cycles per yearover a 25-year calendar service life), cycling has little or no effect on the calendar service lifeof pocket-plate Ni-Cad batteries.

Sintered-Plate - Saudi Aramco does not permit the use of sintered-plate Ni-Cad batteries;therefore, this section is only intended for general information purposes. The primaryapplications of sintered-plate Ni-Cad batteries are those applications that require high-powerdischarge service in a lightweight compact package, such as aircraft turbine engine startingcircuits.

Sintered-plate Ni-Cad batteries are constructed similarly to pocket-plate Ni-Cad batteries.The major difference between the two batteries is the way in which the electrodes (positiveand negative plates) are designed. In the sintered-plate design, the active materials areimpregnated into a porous nickel coating that is applied to an iron grid or charge collector.




Sintered-plate Ni-Cad batteries have nickel oxyhydroxide positive plates and cadmiumhydroxide negative plates. The plates are separated by nonconductive, porous materials thatact as a gas barrier and an electrical separator. The electrolyte is a dilute KOH solution, and itcompletely covers the plates and separators.

Figure 7 shows the construction of a typical sintered-plate Ni-Cad battery. The batteryconsists of a plate pack that contains the positive plates, the negative plates, and theseparators. A terminal comb is placed over the negative plate tabs to connect the negativeplates. A separate terminal comb is placed over the positive plate tabs to connect the positiveplates. The assembled plate pack is then placed in the cell container. A cell cover is placedon top of the cell container, and it is sealed to the container. A terminal is connected to thepositive terminal comb and to the negative terminal comb. The terminals are used to connectthe battery to the external load. The removable vent cap allows excess gases to escape and ameans to add electrolyte.




Typical Sintered-Plate Ni-Cad BatteryFigure 7




The advantages and disadvantages of sintered-plate Ni-Cad batteries are shown in Figure 8.

Advantages and Disadvantages of Sintered-Plate Ni-Cad BatteriesFigure 8

As was noted in Figure 8, the sintered-plate Ni-Cad battery is more expensive than the ventedpocket-plate battery and many times more expensive than the sealed lead-acid battery.

The average calendar life of a sintered-plate Ni-Cad battery ranges from three to ten years,and the cycle life ranges from 500 to 2000 equivalent full charge cycles. The cycle life andcalendar life are strongly influenced by the method of operation, the ambient temperatureconditions, and the depth of discharge. The best battery life performance is obtained fromoperation at normal temperatures and at moderate (50% average) discharge depths. The lifeof sintered-plate Ni-Cad batteries drops when the battery is subjected to frequent deep orshallow discharges.

Number of Cells




The nominal voltage that is required by the load that is connected to a battery is the factor thatdetermines the number of cells that are required; however, the voltage at which a batterysystem operates is not constant. The voltage fluctuates between minimum and maximumfixed values dependent on the state of charge. The range of voltages that lies between theminimum system voltage and the maximum system voltage is the voltage operating "window"for the battery system. The size (number of cells) of the battery is selected to ensure that thebattery operates inside of the voltage window.

For batteries that supply dc systems, the minimum and the maximum battery system voltagesare based on the voltage rating of the most limiting load. The minimum system voltage isselected to ensure that sufficient voltage is available to operate the loads at the end of thebattery duty cycle. The maximum system voltage is selected to ensure that the voltage ratingof the loads will not be exceeded when the battery is being recharged. The following are theminimum and the maximum battery system voltages for Saudi Aramco dc systems:

Nominal System Voltage Minimum System Voltage Maximum System Voltage12 vdc 10.5 vdc 15.5 vdc24 vdc 21.0 vdc 30.0 vdc48 vdc 42.0 vdc 58 vdc120/125 vdc 105 vdc 143 vdc240/250 vdc 210 vdc 286 vdc360/375 vdc 315 vdc 429 vdc

For batteries that supply UPS systems, the minimum and the maximum battery systemvoltages are based on the allowable dc input voltage ratings of the UPS system. Theallowable dc input voltage ratings are specified by the manufacturer of the UPS system.

For batteries that supply a combined dc and UPS system load, the minimum and themaximum system voltages for dc systems should be used.

Because the battery system voltage is the product of the individual cell voltages and thenumber of cells that are connected in series, the minimum and the maximum battery systemvoltage values are used to determine the minimum and the maximum number of cells that canbe used in a battery installation. The following equation, which is also included in Work Aid2, can be used to calculate the minimum number of cells that can be used in an installation.

For most applications, the final volts per cell for lead-acid batteries is 1.75, and the final voltsper cell for Ni-Cad batteries is 1.1 volts. If justified by valid engineering and economicreasons, other final volts per cell values could be used.

The following equation, which is also included in Work Aid 2, can be used to calculate themaximum number of cells that can be used in an installation:




The maximum cell voltage on charge for lead-acid batteries is the equalizing voltage that isrecommended by the manufacturer. If the manufacturer's data are not available, a value of2.33 volts per cell can be assumed. The maximum cell voltage on charge for Ni-Cad batteriesis the charging voltage that is recommended by the manufacturer. If the manufacturer's dataare not available, a value of 1.55 volts per cell can be assumed.

After the minimum and the maximum number of cells are known, the actual number of cellscan be specified. The actual number of cells that are specified can be any number that liesbetween the minimum and the maximum number. For consistency and ease of specification,SAES-P-103 contains the following information that lists the number of lead-acid or Ni-Cadcells that are to be specified for various nominal battery system voltages:

Nominal BatterySystem Voltage

(vdc)Number of Cells

Lead-Acid Ni-Cad12 6 1024 12 1948 24 37120/125 60 92240/250 120 184360/375 180 276

The equations serve as a second check to verify that the number of cells listed is correct forthe application.

For example, if a new lead-acid battery is needed to supply emergency power for a dc systemwith a nominal voltage of 120 vdc, the number of cells that is required is determined asfollows:

• From the table that is in SAES-P-103, 60 lead-acid cells are required for a nominalbattery system voltage of 120 vdc.

The number of cells that was determined from the table can be verified as follows:

The above calculations verify that 60 lead-acid cells are adequate for this installation.

Duty Cycle




The duty cycle of a battery is defined as the load currents that a battery is expected to supplyfor specified periods of time. This information is critical in the determination of the properamp-hour rating of a battery.

The proper size of a battery depends not only on the nominal current rating or the kW draw,but it also depends on the duration of each load (i.e., the duty cycle). Additionally, the batterysize also depends on the sequence in which the load is energized. Careful scheduling of theload sequence in the duty cycle may allow the cell size to be smaller, which can reduce thecost of the installation.

Most stationary battery installations are multi-load systems rather than single-load systems.When a variety of loads are connected to a battery, sudden increases and decreases in currentdemands are imposed on the battery. If the high-current loads can be scheduled to energize atthe beginning of the duty cycle rather than at the end of the duty cycle, a smaller-sized batterycan be used. However, if the load is random in nature and could occur at any time during theduty cycle, the best practice is to assume that the load will energize at the most limiting pointin the duty cycle when its effect will be the most severe.

A duty cycle diagram is a tool that aids in the analysis of the duty cycle and in thedetermination of the required battery capacity. A duty cycle diagram shows the total requiredbattery current at any given time in the duty cycle. To prepare such a diagram, all of the loadsthat are expected during the duty cycle are tabulated along with their anticipated start and stoptimes.

The loads that have known start and stop times are plotted on the duty cycle diagram as theywould occur. The remainder of the loads should be plotted through use of the followingguidelines:

• If the start time for a load is known but the stop time is indefinite, the load isassumed to be continuous for the remainder of the duty cycle.

• If the load can occur at random, the load is assumed to occur at the most criticalpoint in the duty cycle to simulate the worst-case condition. The most critical pointin the duty cycle is the point that controls the size of the battery that is needed.

Figure 9 shows an example of the duty cycle diagram that would be plotted from thefollowing hypothetical loads:

• L1 represents 50 amps of continuous emergency lighting load for three hours.




• L2 represents 100 amps of momentary switchgear operations load and 250 amps ofmomentary motor starting load.

• L3 represents 50 amps of noncontinuous motor load for one and a half hours.

• L4 represents 100 amps of noncontinuous load that starts after 30 minutes andstops after one hour of operation.

• L5 represents 50 amps of momentary switchgear operations load that occurs duringthe last minute of the duty cycle.




Duty Cycle DiagramFigure 9

Cables

Battery cables are an important link between the battery energy and the load. Cables must beselected and installed so that they will carry the anticipated current for the maximum length oftime that the battery is expected to discharge into the load. Cables must be insulated with aconductor insulation that is suitable for the expected operating temperatures and corrosiveeffects of the battery electrolyte and gases. The cables must also be sized to provide aminimum voltage drop at the load. Excessive voltage drop could cause equipment to fail tooperate or to shut down prematurely as the battery voltage decreases during a discharge cycle.If the battery cables fail to carry the current to load when required, serious consequences mayresult, and the function of critical equipment response might be endangered. Battery cablesrequire only a few major considerations to ensure that their operation is reliable.

Battery cables must be sized of an ampacity that is large enough to carry the load withoutexceeding the temperature limitations of the conductor insulation and without excessivevoltage drop. The ampacity of the battery conductors is calculated through a determination ofload current conditions. These conditions are the amount of load current and the maximumexpected duration of the current. The actual AWG size of the conductors is determinedthrough use of tables, such as tables 310-16 and 310-17 in the National Electrical Code,




NFPA-70. The battery cables that are selected must be stranded copper conductors that areinsulated with a material that is suitable for the nominal battery voltage and that are resistantto corrosive atmospheres and liquids. Most thermoplastic and rubber insulated conductors areresistant to acid and caustic atmospheres that are common to battery rooms; special insulationis not required.

The actual voltage drop due to the resistance of the battery cable conductors can be easilycalculated. The factors that are necessary to calculate the voltage drop are the maximum loadcurrent, the one-way distance to the connected load, and the AWG or kcmil size of the batterycable conductors. The following formula is used to calculate actual voltage drop:

VD = 2 x L x R x I / 1000

where: L = one-way length of the circuit to the farthest point

R = dc resistance of the conductor per 1000 linear feet

I = maximum expected continuous load current to the load

The dc resistance per 1000 ft. can be found in Table 8 (Conductor Properties) of the NationalElectrical Code.

The voltage drop that is calculated from this formula must be no greater than 3% of thebattery nominal voltage.

Battery cables should be connected through use of terminals that are suitable for that purpose.The cables should be run from the battery's positive and negative terminals to a battery circuitbreaker. This breaker is the disconnect point for the batteries, and it should be equipped withan undervoltage trip feature that will open the battery's circuit if the battery's voltage drops toa value of 5% below the battery's final discharge voltage. The requirement for theundervoltage trip does not apply to batteries that supply emergency or life-critical loads.

Battery Chargers

Saudi Aramco dc systems require battery chargers that operate on constant-potential, semi-conductor, static-type chargers. These chargers are designed to simultaneously supply dcpower to a float-type battery and to provide power to the connected dc loads. The followingtwo basic types of chargers are used:

• Static Plate Rectifier• Solid State Rectifier




Static Plate Rectifier

The static plate rectifier can contain selenium discs or a group of copper or aluminum discsthat contain oxidized selenium or silicon on one side. The discs are clamped together andhave electrical connections on both sides. The discs are supported on an insulated shaft that issecured through use of insulator clamps at each end. The static plate rectifier is mounted inthe battery charger housing through use of a mounting clasp that is connected at the ends ofthe static plate rectifier. Figure 10 shows a single-unit static plate rectifier.

The static plate rectifier converts an ac input to a dc output. The static plate rectifieraccomplishes this conversion by allowing current to flow only in one direction. When an acvoltage is applied to the static plate rectifier, current can flow from the oxidized side of thedisc to the adjacent copper or aluminum side, but current cannot flow in the oppositedirection. This rectification principle is known as half-wave rectification.




Static Plate RectifierFigure 10

Figure 11 shows two possible ways that static plate rectifiers can be configured to produce adc output. Figure 11A is a half-wave rectifier circuit. In this circuit, an ac voltage (EAC) isapplied to the circuit through the transformer secondary winding. The static plate rectifieronly allows current to flow in one direction through the load. The voltage that is applied tothe load will only occur during one half of the applied ac sinewave; therefore, the shape of theresultant EDC is a series of half peaks and flat spots.

Figure 11B shows a full-wave rectifier circuit. The full-wave rectifier also receives ac powerfrom a transformer secondary winding; however, two static plate rectifiers are connected inthis circuit. The load is connected between the static plate rectifiers and a center tap of thetransformer. The two static plate rectifiers are electrically connected so that one rectifierconducts on the positive half-cycle of the ac supply voltage, and the other rectifier conductson the negative half-cycle of the ac supply voltage. The output (EDC) to the dc load is a full-wave voltage.




Static Plate Rectifier OperationFigure 11

The static plate rectifier replaced the old motor-generator systems. Because a static platerectifier has no moving parts, it is smaller and requires less maintenance than the motor-generator systems. One disadvantage of the static plate rectifier is the heat that is generatedfrom the flow of current through the resistance of the oxide layer. This heat decreases theefficiency and increases the cost of operating static plate rectifiers.

Solid State Rectifier




The solid state rectifier-type of battery charger uses power diodes and/or silicon controlledrectifiers (SCR's) to convert ac to dc. Figure 12 shows a simplified diagram of a solid staterectifier. The operation of the solid state rectifier is very similar to the operation of the staticplate rectifier. The diodes that make up the solid state rectifier only allow current flow in onedirection. The diodes are arranged to provide a path for current flow during each half cycle ofthe input ac sinewave. The input ac sinewave is supplied to the solid state rectifier from themulti-tap transformer secondary. Multi-tap transformer secondaries permit a coarsemechanical adjustment of the voltage that is supplied to the dc load.

During the positive half of the ac sinewave, diodes D1 and D4 conduct, which allows currentflow to the system battery from negative to positive. During the negative half of the acsinewave, diodes D2 and D3 conduct, which also allows current flow to the system batteryfrom negative to positive. The diode pairs alternately conduct as long as an ac sinewave isapplied that maintains dc current flow to the system battery from negative to positive. Theresultant output wave shape that is supplied to the system battery is also shown in Figure12.

The major advantages of the solid state rectifier are that it is smaller and more efficient thanthe static plate rectifier. The main disadvantage of the solid state rectifier is that it costs morethan the static plate rectifier.




Solid State RectifierFigure 12

Current and Voltage Ratings

The standard continuous-duty direct current output ratings of Saudi Aramco battery chargersmust be one of the following values:

1A, 3A, 6A, 12A, 15A, 20A, 25A, 35A, 50A, 75A, 100A, 150A, 200A

Battery chargers that are larger than 200A must be rated in 100A increments.

The ac input voltage ratings are based on the available ac voltage and the required systemoutput voltage. The following are the nominal ac input voltages for Saudi Aramco batterychargers:

• 120 vac• 208 vac• 240 vac




• 480 vac

The output voltage ratings of a battery charger are dictated by the type of battery that thecharger is intended to charge. The output voltage ratings of the battery charger are based onthe float, equalizing, and final volts per cell of the battery to which it is connected. Themaximum voltage output of the battery charger is equal to the following:

Battery charger maximum output voltage = Equalizing voltage per cell x number of cells

Figure 13 shows the typical volts per cell ratings for different types of batteries. The float,equalizing, and final volts per cell ratings are multiplied by the number of cells that are in thebattery to determine the necessary battery charger output voltage rating.

Typical Volts Per Cell Ratings for Different Battery TypesFigure 13

Operational Requirements

The operational requirements for Saudi Aramco battery chargers fall into the followingcategories:

• Output Regulation• Controls• Filters

Output Regulation

The voltage output of a battery charger must be regulated to ensure that the proper chargevoltages are applied to the battery. Charge voltages that are outside of the tolerances of thebattery could cause excessive gassing in the cells. The exact amount of output voltage controlthat is required depends on the rated size of the battery charger and the type of charge that isbeing performed. The following are the output voltage regulation requirements for SaudiAramco battery chargers:




Battery Charger Size Float Operation Mode Recharge (Equalize) OperationMode

< 10 kW +/- 1% +/- 2%> 10 kW +/- 1% +/- 1%

Battery charger output regulation also refers to the battery charger's ability to maintain therated output during operation of the battery charger. A battery charger must be able tomaintain nominal rated voltage output during load changes, battery removal, and variations inthe input voltage. The battery charger output voltage must return to within the previouslymentioned limits within two seconds when the load is changed or when the battery isremoved, and no voltage variation should result in exceeding the rated output voltage. Thebattery charger also must maintain an output voltage that is within the specified voltagetolerances during variations in the battery charger input voltage.

Controls - Separate and independent controls are required for the adjustment of the float andrecharge (or equalizing) voltage. The battery charger must provide the following ranges offloat voltage output control at its nominal ac input voltage and half load:

Adjustment Range Per CellLead-Acid Cells 2.15 - 2.25 VPCNi-Cad 1.40 - 1.47 VPC

The battery charger should also provide the following ranges of equalizing voltage control atits nominal ac input voltage and half load:

Adjustment Range Per CellLead-Acid Cells 2.25 - 2.40 VPCNi-Cad Cells 1.50 - 1.65 VPC

The following formula is used to calculate the required float and equalizing voltage controlranges for battery chargers:

Charger Output Voltage = VPC x Number of Cells

For example, the required float and equalizing voltage control range for a 60-cell, lead-acidbattery is calculated as follows:

Float Voltage Adjustment Range:




Minimum Charger Output Voltage = VPC x Number of Cells= 2.15V x 60= 129V

Maximum Charger Output Voltage = VPC x Number of Cells= 2.25V x 60= 135V

Equalizing Voltage Adjustment Range:

Minimum Charger Output Voltage = VPC x Number of Cells= 2.25V x 60= 135V

Maximum Charger Output Voltage = VPC x Number of Cells= 2.40V x 60= 144V

The battery charger must also have an input circuit breaker and an output circuit breaker ordisconnect switch. The input circuit breaker must have an interrupting capacity that is equalto or greater than the available short-circuit current. The minimum capacity is 14,000symmetrical rms amps. Current-limiting fuses may also be provided to meet the short-circuitcurrent requirements. The output circuit breaker or disconnect switch must be able tosimultaneously disconnect both output lines.

Supervisory Controls

The battery charger should be equipped with the following supervisory control circuits:

• End of Discharge Relay Circuit - The end of discharge relay senses the battery busvoltage and actuates when the battery has discharged to a predetermined level.The end of discharge relay should activate when the battery voltage equals 1.75VPC for lead-acid batteries and 1.10 vpc for Ni-Cad batteries. The setpoint of therelay should be adjustable from +5% to -5%. Operation of this relay indicates thatthe battery needs to be charged.

• Ground Detection Relay Circuit - The ground detection relay senses ground faultson the positive or the negative battery bus. Operation of this relay indicates thepresence of a ground fault.




• Equalizing Timer Circuit - The equalizing timer allows unsupervised control of theequalizing charge. The timer is manually set to the desired equalizing time period.When the battery charger is placed in the equalize charge mode, the timerautomatically returns the battery charger to the float charge mode after the presettime has elapsed.

• Low Voltage Relay Circuit - The low voltage relay provides an indication that thedc output voltage has dropped below a preset value. This relay must be adjustableto allow for field settings of the minimum battery output voltage.

• Overvoltage Relay Circuit - The overvoltage relay provides an indication that thedc output voltage has increased above a preset value. The relay must be adjustableto allow for field setting of the maximum battery output voltage.

• Charger Failure Relay Circuit - The charger failure relay provides an indication ofa loss of the charger's dc output. The battery charger failure relay actuates on acharger output failure regardless of the cause. The charger failure relay is intendedto alert the operator that the charger is no longer in operation, but it does notprovide an exact indication as to the cause of charger output failure.

• Low Current Relay - The low current relay provides an indication that the dcoutput current of the battery charger has dropped to a value that is less than twopercent of the rated output.

Filters

Filters are placed on the output of a battery charger to reduce the ac ripple that is in the dcpower that is supplied to the system load. The filter requirements for Saudi Aramco batterychargers vary dependent on the size of the battery charger and the type of dc load.

The ac ripple voltage of battery chargers that are rated for 10 kW or less should be filtered toa maximum of 30 mV rms or 100 mV rms dependent on the requirements of the connectedload. For most applications, the ripple voltage is required to be less than 1-2% of the nominaldc voltage, with a +/- 10% line voltage deviation and with a load variation of 0-100%. Thebattery chargers that supply dc systems that are dedicated to only emergency lighting systemsdo not require filters.

Environmental Ratings




Battery chargers normally are operated inside of buildings that are air conditioned to 25°C(77°F). However, in the event of a loss of air conditioning, the battery chargers must be ratedto operate for a period of eight hours in the following environment:

• Ambient temperatures that range from 0°C (32°F) to 50°C (122°F).• Relative humidity up to 100%.• Sand, salt, and dust-laden atmosphere.

Ancillary Items

There are several ancillary items that are necessary to support the operation of batterysystems. These items include the battery room, a ventilation system, and showers or eyewashstations. Battery rooms are constructed with features that provide isolation of the battery andits associated components from other areas of a facility. Because most batteries emit someamount of hazardous vapors, the atmosphere that surrounds the battery must be properlyvented. Ventilation systems ensure that an accumulation of hazardous gases will not occur.

Within battery rooms and in close proximity of the battery, emergency showers or eyewashstations are installed for the safety of personnel. Personnel must have quick access to thesesafety items any time that routine maintenance is performed or other work is done thatinvolves the batteries. During the commissioning process, these items must be inspected toverify that they are correctly installed and that they will function properly.

These ancillary items must be carefully scrutinized during the commissioning process toensure that all the required components are present and that they are installed correctly and inaccordance with the governing standards, such as the National Electrical Code, NEMA PE 5-1985, Saudi Aramco Engineering Standards, and Saudi Aramco Materials SystemsSpecifications.

Battery Rooms

The battery room is constructed to accommodate the battery and its associated equipment withenough area to allow easy access to the battery for routine maintenance. The actual workingspace is determined through use of calculations that are primarily based on the type, size, andnumber of cells of the battery. The minimum height of battery rooms should be no less thanthree meters, which allows any H2 to accumulate far away from the tops of the cells. Thehigh ceiling also contributes to a larger overall volume of the battery room, which tends toreduce the overall concentration of H2.

The battery room should be designed with sufficient working space around the battery. Aminimum of 1 m (3 ft.) of work space is required on all four sides of the battery. Thismeasurement is the distance from the exposed live electrical components and the associated




equipment to ground. Space in the battery room must also be provided for the easymovement of equipment in and out of the room and for ease of maintenance. Finally, thebattery room should be designated as a battery room only, and it should not be used as astorage room or a supply room.

The surface of battery room floors and walls are sealed to prevent the leakage of gases toadjacent rooms or spaces. The lower 150 mm (6 in.) of the wall and the floor are additionallycovered with a protective paint that is resistant to acids and caustics. This protective paintensures that a spill of electrolyte will not damage the floor or leak into adjacent areas.

Penetrations through the battery room walls should not be more than 2.1 m (7 ft.) from thefloor except for air conditioning and ventilation ducts. Where these types of penetrationsexist, they must have vapor-tight seals around them, which ensures that any collection of H2gas will be expelled through the ventilation system ducts.

Battery rooms are equipped with doors that open out and away from the battery; in the eventof an emergency, rapid exit of personnel is not impeded. Additionally, an inward openingdoor would tend to seal itself closed if pressure in the battery room were to suddenly increaseas the result of fire or explosion. The battery room door should not contain any sort of devicethat would prevent the door from opening.

Lighting fixtures that are located in battery rooms are suspended from the ceiling so that thefixtures will be below a level where H2 gas would accumulate. Lighting fixtures arepositioned directly over the battery racks for the best illumination of the cells and batteryracks. The lighting fixtures should be listed or labeled for the specific purpose, and theyshould be resistant to corrosion that is caused by acid fumes. Switches for lights and othersimilar devices are installed at least 1.5 m (5 ft.) from the battery cells.

Detailed information on the method of calculating the size of the battery room can be found inEEX 211.05.

Ventilation

Battery room ventilation systems are designed to prevent a concentration of H2 gas that isgreater than 2%. Two percent is a concentration that is considered adequate for safety.Concentrations of less than 2% are not considered sufficient to allow an explosion.

Because adequately-sized exhaust ducts permit the ventilation system to supply positive airpressure, most battery rooms in Saudi Aramco facilities will not have exhaust fans. Thispositive air pressure will be great enough to maintain the correct amount of air exchange inthe battery room. Battery rooms that meet the battery room ventilation requirements of SaudiAramco are not classified as hazardous locations and, therefore, are not required to includeexplosion-proof devices or wiring methods.




If the type of battery that is installed in a Saudi Aramco facility is a lead-acid battery, thebattery room must be air conditioned. The air conditioning system must be able to maintainthe temperature in the battery room at 25_(77_F). If the area in which the battery is located isunmanned and if air conditioning is not feasible, a Ni-Cad battery is normally selected insteadof a lead-acid battery, and air conditioning is not required. Air-conditioned rooms must notcontain return air ducts that would allow corrosive fumes or H2 gas to mix with the buildingair.

Detailed information regarding the methods of determining the ventilation requirements canbe found in EEX 211.05.

Showers/Eyewash Stations

Battery rooms in Saudi Aramco facilities will have floor drains to accommodate eyewash andshower installations. Eyewash stations are installed within the battery room so that a workercan immediately flush his face or eyes with water in the event of an accidental splash ofelectrolyte into the employee's face or eyes. Large battery rooms may be outfitted withemergency showers that would allow a worker to quickly wash large spills of electrolyte fromhis body. If eyewash stations or shower facilities are installed, the floor of the battery roommust include one or more floor drains. The drains must be installed in accordance with therequirements of SAES-P-060, Saudi Aramco Plumbing Code. This code specifically requiresthat the battery room be provided with a floor drain that is trapped and vented to serveeyewash facilities and washdown of electrolyte spills.

Some of the particular requirements for eyewash stations and emergency showers arespecified in SAES-B-069, Emergency Eyewashes and Showers. The following is a summaryof those requirements as they apply to battery rooms:

• Eyewashes and showers must be constructed of material that is resistant tocorrosion from the effects of the battery room atmosphere. The plumbing that isconnected directly to the eyewash station or shower must be constructed ofgalvanized pipe, and the other piping from the supply may be PVC, CPVC, orcopper. The connection branch may also be galvanized pipe if it supplies only theeyewash and shower.

• The eyewash station and shower must be supplied from a suitable potable watersupply that is certified to be suitable for the purpose by Saudi Aramco's MedicalService Division.




• The eyewash and shower must be able to provide a continuous flow rate for at least15 minutes at a pressure that is no greater than 207 kPa (30 psig) and at atemperature that is not greater than 37.8_(100_F) except for the short period oftime where water is naturally heated from the environment by above-groundpiping. The pressure must be maintained through use of pressure controllers orself-regulating orifices that prevent the pressure from being greater than 207 kPa ifthe system is capable of delivering higher pressure at the eyewash and showeroutlets.

• The shower and eyewash stations must be located no closer than 3 m (10 ft.) andno further than 15.2 m (50 ft.) from the nearest battery cell. The shower andeyewash stations must also be easily accessible without going through doors or upor down stairs, and it must be adjacent to the normal exit from the battery roomand in a well-lit area.

• The eyewash and shower area must be indicated by a background area that ispainted with alternate green and white diagonal stripes that are approximately 152-mm wide and that cover an area 1 m wide by 2 m high. A sign that indicates bothstations and the emergency procedures for each must be posted.

• The eyewash and shower stations may be equipped with an alarm that is activatedwhenever either facility is operated. The determination of whether an alarm isneeded is made by the Industrial Hygiene Unit of the Medical Services.

• During the commissioning of battery systems, the installation of showers andeyewash stations must be carefully inspected to ensure that they meet therequirements of SAES-B-069 and that they function properly.




EVALUATING BATTERY AND BATTERY CHARGER SYSTEMS UPON RECEIPT

The components of battery systems must be evaluated upon receipt to ensure that they meetthe relevant Saudi Aramco Material Standards and Specifications. This verification should beperformed as soon as receipt of the equipment occurs so that any discrepancies that are notedcan be resolved before the equipment is installed. The primary focus of this verification is toensure that the equipment is not damaged and that the nameplate data and manufacturer'sinformation that are provided correspond to the electrical drawings and material andequipment specifications.

Verify Against Specification

Many items should be verified and inspected during the receipt inspection of battery systems.These items include the battery cells, the battery racks, the interconnecting links, the batterycharger, and ancillary items, such as ventilation equipment.

Battery cells must be verified against the information that is provided on the data schedule toensure that the type of battery that was received is the type of battery that was specified on thedata schedule. This verification includes a careful review of the manufacture's literature,which should accompany the battery and associated hardware, for compliance with the SaudiAramco specifications.

The information that is contained in the manufacturer's data should indicate that the batterywill meet the load requirements as described on the data schedule. This information isnormally provided by the manufacturer in the form of a load vs. time graph of battery cellperformance.

The battery charger should be inspected in a manner that is similar to the inspection forbattery cells. That is, the battery charger should be verified against the data specificationsheet to ensure that it meets all the requirements that are listed, as well as compliance withSaudi Aramco Materials Systems Specifications 17-SAMSS-514 and NEMA PE 5-1985. Thebattery charger receipt inspection should include a verification of hardware and accessoryequipment to ensure that all the components are on hand before installation begins.Verification of all accessory equipment that is specified in the data schedule, such as relays,alarms and indicating devices, and protective devices must be completed.

The battery charger enclosure must also be inspected upon receipt to verify that is meets therequirements that are specified in 17-SAMSS-514 and the requirements of NEMA ICS 6,Type 1 enclosure.

Other items that are associated with the battery and battery charger system must be accountedfor during the receipt inspection. The material and equipment schedule that accompanies theelectrical drawings for the battery system installation should be the reference that is checkedwhen this receipt inspection is performed. Any missing or damaged items should be




identified as soon as possible so that corrective action can be taken and the project progress isnot delayed.

A complete and detailed description of these inspections and verifications is contained inWork Aid 1.

Physical Inspection

At the same time that the verification of the battery and battery charger system is confirmedagainst specification, a complete physical inspection should be performed. The items thatshould be visually and physically inspected are briefly described in the following paragraphs.Details of this physical inspection are included in Work Aid 1.

The battery cells must be visually inspected to ensure that the manufacturer took the propersteps to prevent damage and contamination of the cells during shipment. Properdocumentation that explains the shipping and storage procedures should accompany thebatteries and associated equipment.

A physical inventory of all the major items of the accessory equipment must be performed.Battery hardware, such as intercell connectors, terminal connectors, and rack hardware mustbe accounted for and inspected for compliance with specifications and for indication ofdamage.

The battery rack and associated hardware should be visually inspected to verify that they areof the correct size and material composition in accordance with the drawings andspecifications. This inspection includes verification that the rack framework is properlycoated with the specified protective material to prevent corrosion.

Physical inspection includes verification of the inventory of all required accessories, such asshower and eyewash equipment, safety protective gear, tools, and test equipment, as well asthe battery charger accessory devices.




EVALUATING BATTERY AND BATTERY CHARGER INSTALLATION ANDTESTING

The commissioning of batteries and battery chargers must include a series of installationchecks and tests to confirm that the battery system will function as designed. The Engineershould evaluate the results of these tests and check points, and he should reconcile anydiscrepancies that are identified. A battery system that has not met commissioning criteria butthat is allowed into service can lead to a catastrophe.

Batteries

The battery cells should be inspected to verify that they are correctly installed on the batteryracks. The intercell connectors, battery cables, and connection to the battery disconnectswitch should be inspected to verify that these components are properly installed. The boltsfor the intercell connectors and battery cable terminals should have been applied to thespecified torque for the given size bolt.

When battery cells are inspected, the inspection personnel should verify that the battery cellshave been filled with the correct type electrolyte at the correct specific gravity. Theinspection personnel should also verify that the electrolyte level is within the upper and lowerindicating lines on the cell jar.

The inspection personnel should also verify that the battery rack has been properly assembledand that all metal parts are manufacturer. Prior to the battery cell installation, the inspectionpersonnel should ensure that battery cell covered with the protective coating that is suppliedby the internal resistance measurements have been taken and recorded.

Electrolyte

The battery electrolyte for lead-acid batteries consists of a dilute solution of sulfuric acid. ForNi-Cad batteries, the battery electrolyte consists of potassium hydroxide. After lead-acidbattery cells have been filled with electrolyte, and after the battery receives its "fresheningcharge," the specific gravity of each cell must be read and recorded. The freshening chargemust not be applied to the battery unless the electrolyte level is above the low-level line on thecell jar. The freshening charge must be applied for a period of time that is specific for eachtype of lead-acid battery and the required specific gravity. Figure 14 shows the charging timeand per cell voltage that are required to obtain the desired specific gravity that is specified bythe battery manufacturer.




Charging Time and VPC to Obtain Desired Specific GravityFigure 14

During the freshening charge process, the electrolyte temperature must be monitored, and itshould not be allowed to exceed 110°F (43°C). The charging should be interrupted and thebattery should be permitted to stand open circuited if the temperature exceeds 110°F (43°C).When the cells cool down to 100°F (38°C), the charging may be resumed.

When the battery has been properly filled and charged in accordance with manufacturer'srecommended procedures, the battery is then placed on the float voltage. This voltage shouldbe provided by the battery manufacturer; Figure 15 provides the average volts per cell forfloat charge based on the nominal specific gravity for lead-acid cells. After the battery hasbeen initially charged and has been on float charge for at least 72 hours, specific gravityreadings can be taken. The specific gravity readings should be corrected for temperature. Forevery 3°F (1.67°C) above 77°F (25°C), one point (.001) should be added to the specificgravity reading. For every 3°F (1.67°C) below 77°F (25°C), one point (.001) should besubtracted from the hydrometer reading.




Average Float Volts Per Cell for Nominal Specific Gravities ListedFigure 15

Chargers

After the installation is complete, battery chargers should be checked for the following items:

• The battery charger wiring from the ac supply to the charger and the dc outputconductors (battery cables) should be checked for correct wiring practices.

• The size of conductors and type of insulation should be verified.

• The conductors should be checked to verify that they are insulated stranded copperconductors with a thermoplastic insulation that is suitable for battery roominstallation.

• The battery charger should be checked to verify that it is attached to the equipmentground circuit of the ac supply in accordance with Article 250 of the NEC.

Figure 16, NEC Table 250-95, provides the required size of the equipment groundingconductors for battery chargers.




NEC Table 250-95: Sizes of Equipment Grounding Conductors for Battery ChargersFigure 16

The charger output is checked for proper operation through verification of the outputconditions. The settings for the float voltage and for the equalize voltage should be verifiedagainst the data schedule and battery manufacturer's requirements. An accurate voltmetershould be used to measure the voltage at the output terminals of the battery charger and thenacross the positive and negative terminals of the battery. The difference of these two voltageswill indicate the voltage drop of the battery charger input circuit. This voltage drop should beminimal.

The voltage output of the battery charger must checked to verify that the charger voltage willbe regulated within the specified limits listed on the data schedule. A guide for the percentvoltage regulation requirements is provided below.

Battery Charger Size Float Operation Mode Recharge (Equalize) OperationMode

< 10 kW +/- 1% +/- 2%> 10 kW +/- 1% +/- 1%




BATTERY AND BATTERY CHARGER SYSTEM OPERATIONAL TESTINGREQUIREMENTS

The battery charger should be tested to ensure that the battery charger is capable of deliveringthe specified current output to the battery for the specified time as indicated on the dataschedule. The battery should be load tested to confirm that it will deliver the specified valueof current to the load for the specified length of time without reaching the final dischargevoltage. These tests are best accomplished through use of a load bank of sufficient rating.The float and equalize settings should be verified, and the actual value of these settings shouldbe measured under various conditions of charge rate and load. When the charger is operatedwithin the specified current capability, the charger voltage regulation should maintain outputvoltage under all conditions.

Charging Rate

The charging rate of the battery charger can be verified by connecting the charger to the loadbank and adjusting the load to a value that will cause the charger to deliver the specifiedoutput current. The charging rate verification test should be run for the length of time that isrequired on the data schedule. During this test, the battery charger output voltage should becontinuously monitored to ensure that it is maintained within the specified limits.

Discharge Rate

The battery must be tested for its ability to discharge into the load and provide the rated valueof current for the specified length of time without reaching the final voltage. This test isaccomplished through use of a load bank. The battery output is connected to the load bank,and the load bank is adjusted to cause the battery discharge current to equal the dischargecapability that is listed on the data schedule. An accurate voltmeter should be connected tothe battery output so that voltage readings can be monitored and recorded at regular intervalsduring the test.

Float/Equalize Settings

After all the charger and battery testing is complete, a final check of the float setting and theequalize setting should be confirmed. The float and equalize settings should provide aconstant voltage output through battery cycles of charging and discharging.




Charging Capacity (Amp-Hour Rating)

The battery charger ampere output is listed on the nameplate, and it can be calculated throughuse of the following formula

A = ( SF * L + (BIF * AH/RT) ) /Kt

Where: A = Ampere rating of the charger.SF = Service factor: 1.1.L = Sum of continuous dc loads (amperes).BIF = Battery inefficiency factor: 1.15 for lead-acid batteries and 1.14

for Ni-Cad batteries.

AH = Battery ampere-hour.RT = Recharge time.Kt = Temperature compensation:

Kt = 1.00 at or below 40_C.Kt = 0.83 from 40_C to 50_C.

This rating of the battery charger is verified during the charger charging rate verification thatwas described above.




REQUIREMENTS FOR THE SYSTEM OPERATIONAL OBSERVATION PHASE

After all tests and inspections of the battery system have been completed, and after thecommissioning process has resulted in the battery being placed in service, the battery systemshould be monitored at frequent intervals for several weeks. The purpose of this observationphase is to carefully monitor the battery and charger under all conditions of service for anysigns of improper or erratic operation.

The items that should be observed include all parts of the battery system. The charger outputshould be monitored by observing and recording the output voltage and current. The chargerwiring should be inspected to note any signs of poor connections, overheating, or othersimilar problems.

The battery should be observed for any signs of cell overheating, excessive loss of electrolyte,leaking cell jars, and loose battery connections.

Specific gravity tests should be conducted and recorded after the battery has been in normalservice for a period of time. The specific gravity of all cells should be within a smallpercentage of each other.

If ac power is lost to the battery charger, the battery will be the sole source of dc power.When a loss of ac power occurs, the battery voltage and discharge rate should be noted.




SUMMARY

As mentioned in the Introduction, commissioning of batteries and battery charger systems ispart of the overall process by which a facility is commissioned. The actions explained beloware required to bring commissioning of batteries and battery chargers to completion.

After the battery has completed the testing and operational observance phase, after all itemshave been verified as satisfactory, the battery system should be accepted as having completedthe commissioning process. Maintenance intervals should be established so that allcomponents of the battery system that require routine maintenance are placed on a periodicmaintenance schedule.

All the commissioning documents, including data schedules, commissioning form P-003,manufacturers' technical manuals, system drawings, and any other related paperwork shouldbe turned over to the appropriate authority for proper custody.

A spare parts inventory should be maintained that is based on the charger and batterymanufacturer's recommendations. This spare parts inventory would include items, such asspare hardware for the battery intercell connectors, battery rack hardware, and spare parts forthe charger internal circuits.

Battery rooms receive a final inspection to ensure that all the items, such as the ventilation orair conditioning system and eyewash and shower facilities, function properly. The inspectionshould include verification that all the accessories that are necessary to maintain the batteryare properly located in the battery room.




WORK AID 1: REFERENCES FOR EVALUATING BATTERIES AND BATTERYCHARGERS UPON RECEIPT

The following information is to be used as a guide for performing Exercise 1. Theinformation that is provided should be used in addition to the Saudi Aramco Battery Pre-Commissioning Form P-003, sheets 1 through 4. (This form is obtained from theInstrumentation unit of the Consulting Services Department.)

Criteria for Evaluating Batteries Upon Receipt

1. Verify that the battery cells are of the type that is indicated on the data schedule. The typeof battery should be one of the following:

• Ni-Cad (pocket-plate)• Plante• Lead-Calcium• Lead-Antimony (maximum 3% antimony)• Tubular Lead (maximum 3% antimony)

Note: Ni-Cad cells must be of the vented pocket-plate construction. Sintered-platecells are not permitted.

2. Verify that the recharge period is as specified on the data sheet.

3. Verify that the number of cells corresponds to the battery nominal voltage.

Nominal BatterySystem Voltage

(vdc)Number of Cells

Lead-Acid Ni-Cad12 6 1024 12 1948 24 37120/125 60 92240/250 120 184360/375 180 276

4. Verify that the battery manufacturer's design float voltage is as indicated on the dataschedule.

5. Verify that the maintenance interval is as indicated on the data schedule, both standardand extended.

6. Verify that the battery design ambient temperature is in accordance with the data schedule.




7. Verify that the electrolyte density corresponds to the data schedule.

8. Verify that the battery load is per the data schedule information or that the battery willaccommodate the load profile that is attached to the data schedule.

Criteria for Evaluating Battery Chargers Upon Receipt

1. The battery charger's nameplate data should be verified against the data schedule throughcomparison of the nameplate data to the following information that is indicated on the dataschedule.

AC Input

Nominal Voltage = or - 10% phases

Frequency 60 Hz + or - 5 %

Available short-circuit current rms symmetrical amperes

Battery Load

Type: Ni-Cad Lead Calcium Plante Lead-Antimony

Charging capacity for hours to final volts per cell.

External dc load (excluding battery)

Amperes Maximum Duty Cycle Description

Output Voltage Range

Floating volts minimum to volts maximumEqualizing volts minimum to volts maximum

Ambient Temperature

Maximum




Minimum

2. The battery chargers for Saudi Aramco dc systems should be constant-potential, semi-conductor, static-type chargers that are designed to simultaneously supply dc power to afloat-type battery and to the connected dc loads. The battery charger that is receivedshould be one of the two types that are listed below as specified on the material data sheet:

• Static Plate Rectifier• Solid State Rectifier

3. Verify that the battery charger meets the requirements of NEMA PE 5-1983 with theadditions and exceptions that are listed in 17-SAMSS-514. The following informationshould be as specified on the data schedule and is an exception to NEMA PE 5-1985:

"Input supply voltage and frequency are as specified on the data schedule."

4. The following items are in addition to the requirements of NEMA PE 5-1985:

• Panel meters that are furnished on the battery charger must have an accuracy of +/- 2%of full scale accuracy, and designed in accordance with ANSI C39.1. Each batterycharger must be supplied with a dc ammeter and voltmeter.

• Printed circuit boards that are contained within the battery charger must meet therequirements of UL 796 and several additional requirements as listed in 17-SAMSS-514.

• The battery charger must be equipped with an end of discharge relay that operateswhen the battery discharges to a voltage of 1.75 volts for lead-acid cells and 1.10 voltsfor Ni-Cad cells.

• The charger should come equipped with a ground detection relay for the dc bus that iscapable of detecting grounds on either the positive or negative bus.

• Battery charger alarm relays must have form "C" single-pole, double-throw relaycontacts.

• The battery charger output voltage regulation must be designed to maintain voltageregulation when the battery is disconnected from the charger (battery eliminationfeature).

• The battery charger is equipped with a filter that meets "limit B" requirements foroutput ripple.




• The battery charger must be equipped with an input circuit breaker that has aninterrupting rating that is equal to or greater than the available short-circuit currentsthat are listed on the data schedule (14,000 rms symmetrical amps minimum). Thisrequirement may be alternately met through use of current limiting fuses of therequired interrupting rating. The circuit breaker must be designed and tested inaccordance with UL 489.

• The charger must be equipped with an output breaker or disconnect switch that willsimultaneously open both output lines.

Enclosures for the battery charger must meet the following requirements:

• Enclosures must be either carbon steel or aluminum, and they must meet therequirements of NEMA ICS 6, Type 1.

• Enclosures must be naturally or force ventilated. If the enclosure is force ventilated, itmust be equipped with removable, easily-cleaned air filters.

• The enclosure must be designed for front access to all components, and it must havedouble or full-length, hinged doors.

• Handles, hinges, and screws must be corrosion resistant.

• Terminal blocks must be provided for connection to external alarm circuits and mustbe of a phenolic, one-piece, barrier-type with pan head screws.

• Insulated compression-type terminals must be provided for all wiring that terminateson terminal blocks. Solder terminals are not permitted for connection to terminalblocks.

• Power cable terminations (lugs) must be the copper-bodied, compression-type(crimped-type) that are suitable for use with ASTM Class B and C strandedconductors.

• All wiring must be stranded copper conductors only.

• Wiring terminal blocks must be identified with thermoplastic slip-on wire markerswith permanently printed characters. The wiring markers must directly correspond tothe numbering found on the schematic.

• Nameplates on the charger must be written in the English language.




• Exterior nameplates are to be attached with stainless steel or brass screws, and internalcompartment nameplates may be attached with permanent adhesive. All devices thatare located within a panel must be identified with a suitable nameplate that identifiesthe item and its function.

The following accessory devices must be provided on the battery charger:

• Equalizing timer• Low voltage alarm relay• Overvoltage alarm relay• Charger failure relay• Low current alarm relay

Physical Inspection

The battery, battery charger, and associated equipment should be physically inspected for thefollowing:

• Lead-acid cells are shipped in a "dry-charged" condition. Each cell should besealed with a moisture-proof vent cap. Ni-Cad cells should be shipped dry,discharged, and sealed with moisture-proof vent caps.

• Individual cells should arrive wrapped and sealed against moisture with adesiccant. There should be instructions contained in each cell shipping containerthat instructs how to correctly lift the cell.

• The shipping information sheet should indicate that the cells should be stored in acool, dry location. The label on the outer wrapping of the cell should include themanufacturer's warranty statement, which includes the storage conditions, date ofshipment, and maximum storage time from date of manufacture.

• The cell accessories should be included with each cell, and they should not beshipped in bulk in a separate package.

• Battery plate material is of the type that is specified in the data schedule. The Ni-Cad cells must be of the vented pocket-plate construction. Sintered-plate Ni-Cadcells are not permitted to be used in Saudi Aramco battery systems.




• The battery containers should be constructed of a heat- and impact-resistant plasticmaterial that is either transparent or translucent. Adequate space must be providedabove the cells to meet the manufacturer's maintenance schedule. The cell jarsshould also have clearly-marked level lines on the sides of the container.

• The cell cover and the container must be sealed properly at the joint between thesetwo parts, which provides a gas-tight seal.

• The cells should be equipped with explosion-proof vent caps that meet therequirements of NEMA-IB-7. These vent caps are designed to allow gases toescape from the cells, but they prevent any flame or sparks from entering the cell.

• The intercell connectors and battery cable terminals should be checked to ensurethey are of the proper size and material to carry the design current and not permitexcessive voltage drop. Ensure that the intercell connectors are of the correct typefor the particular battery. If copper links are used, they must be coated with ahomogeneous lead or lead alloy coating that is no less than 50 micrometers (0.002in.) thick. If the battery is a Ni-Cad-type, the intercell connectors must be nickelplated. Connector bolts, nuts, and washers must be either lead-plated brass orstainless steel (ANSI type 316). The polarity of each cell terminal must be clearlymarked as positive or negative.

• Battery racks should be inspected and verified for the following conditions:

- The racks should be a one- or two-row stepped arrangement that is largeenough to accommodate the number of cells.

- The racks should be no more than two tiers in height.

- The width of the racks must be at least as wide as the battery cell width.

- The racks should be constructed of welded structural steel frames with bolted-on steel runners and braces and with provision for anchoring the racks to thefloor.

- The metal frame of the racks should be coated with an acid-resistant plastic orequivalent material.

• Additionally, a sufficient quality of the battery rack coating material should besupplied by the vendor to take care of nicks and to cover exposed hardware andbolt threads after the racks have been installed.

• A verification of the required accessories should include:




- Battery cell thermometer

- Hydrometer with temperature correction scale (for lead-acid cells)

- Insulated wrenches to fit battery hardware

- Bottle with pour spout for adding distilled water

- Spare intercell connecting hardware and extra rack bolts and nuts that are equalto 10% of the total hardware

- Supply of NO-OX terminal grease (lead-acid only)

- Cell lifting straps or apparatus for cells over 34Kg (75lb)

- Cell voltmeter

All components must be inspected for any visual signs of damage or deterioration duringshipment. This inspection should include items that are broken, bent, cracked, or otherobvious signs of damage. All of the battery cell containers must also be checked. Any effectsof corrosion or moisture damage that often occur during shipping should also be noted.

Saudi Aramco Pre-Commissioning Form P-003, Battery System

The Saudi Aramco Pre-Commissioning Form P-003, Battery System, provides a fieldinstallation checklist for batteries and battery chargers. The pre-commissioning form has abroad checklist of visual and mechanical inspections, as well as the listed electrical tests thatare required for battery and battery charger installations. Space is also provided on the formfor test data. This form is obtained from the Instrumentation Unit of the Consulting ServicesDepartment.




Saudi Aramco Pre-Commissioning Form, P-003, Battery SystemFigure 22




Saudi Aramco Pre-Commissioning Form, P-003, Battery SystemFigure 22 (Cont'd)









WORK AID 2: REFERENCES FOR EVALUATING BATTERY AND BATTERYCHARGER INSTALLATION AND TESTING

The Participant should use Work Aid 2 as necessary to complete Exercise 2.

Procedure for Evaluating Battery and Battery Charger Installation and Testing

1. Verify that the battery and battery rack have been installed correctly. Inspect for properequipment grounding of battery rack, battery charger enclosure, and all non-current-carrying metal parts of the system. Ensure that these components are properly connectedto the equipment grounding circuit. Ensure that all parts of the battery rack have beenpainted with appropriate coating after installation of all rack hardware.

2. Eyewash and Shower Stations

2a. The eyewash and shower stations may be equipped with an alarm that is activatedwhenever either facility is operated. The determination of an alarm is made by theIndustrial Hygiene Unit of the Medical Services. If an alarm is installed, verify that itoperates correctly by operating the eyewash and the emergency shower.

2b. During the commissioning of battery systems, the installation of showers and eyewashstations should be carefully inspected to ensure that they meet the requirements ofSAES-B-069 and that they function properly.

2c. Verify that the eyewash and shower can provide a continuous flow rate for at least 15minutes at a pressure that is no greater than 207 kPa (30 psig) and at a temperature thatis no greater than 37.8_C (100_F) except for the short period of time where water isnaturally heated from the environment by above-ground piping. If the system iscapable of delivering higher pressure at the eyewash and shower outlets, the pressure




must be maintained through use of pressure controllers or self-regulating orifices toprevent the pressure from exceeding 207 kPa.

3. Verify that all accessory equipment is in place, including:

• Safety protective clothing• Hydrometer (for lead-acid cells)• Cell voltmeter• Cell thermometer• Insulated wrenches to fit battery hardware• Bottle with pour spout for battery water• Spare intercell connecting hardware, 10% of total amount• Supply of NO-OX terminal grease (lead acid only)• Cell lifting straps for cells over 34 kg (75 lb.)

4. Verify that the battery intercell connectors are properly torqued and that non-corrosiveprotective coating has been applied to terminal connections.

5. Verify the battery charger operating conditions:

• Float voltage is between 2.25 volts to 2.30 volts per cell for lead-acid cells, or +/- 1.0% of the nominal voltage, or as recommended by the battery manufacturer.

• Equalize voltage should be within +/- 1.0% of the specified equalize voltage that isrecommended by the battery manufacturer. If the battery charger is 10 kW or less, theacceptable value is +/- 2 % of nominal voltage (cell open circuit voltage).

6. Battery Cells

6a. Verify that the battery cell terminal resistance has been measured and that nocell has a resistance greater than 10% or 5 micro-ohms, whichever is greater over theaverage of all the cell terminal resistances.

6b. Cell Specific Gravity (Lead-Acid Only)

After the battery has been fully charged with the freshening charge and allowed toremain on float charge for no less than 72 hours, specific gravity readings can betaken. The specific gravity readings should be corrected for temperature. For every3°F (1.67°C) above 77°F (25°C), add one point (.001) to the specific gravity reading.For every 3° (1.67°C) below 77°F (25°C), subtract one point (.001) from thehydrometer reading.




The specific gravity readings should be such that no cell has a specific gravity that ismore than ten points (0.010) below the average of the specific gravity of all cells aftercorrections for temperature have been made.

6c. Cell Voltage

The acceptable value for cell voltage is that no cell voltage should have a value that islower than 2.10 volts (1.215 specific gravity) for lead-acid cells and 1.29 volts (1.300specific gravity) for Ni-Cad cells.

6d. Battery Discharge Rate

The acceptable value for battery discharge rate is that the battery meets therequirements that are specified on the data schedule and that the battery is inaccordance with the battery manufacturer's specifications.

Unless 100% battery capacity is specified upon delivery, batteries may be less thanrated capacity when received from the manufacturer.

Verify the battery discharge duration by testing. This testing involves discharging thebattery at a pre-determined value of current (based on the battery rating) andmeasuring the time it takes the battery to reach its final voltage per cell (1.75 volts forlead-acid) times the number of cells.

7. Check and Verify the Following Battery Charger Setpoints:

7a. End of charge condition alarm is +/- 5% of the 1.75 volts per cell for lead-acid cellsand +/- 5% of the 1.10 volts per cell for Ni-Cad cells.

7b. Low charger output voltage alarm setpoint is 2.2 volts per cell for lead-acid cells and1.4 volts per cell for Ni-Cad cells.

7c. Ground detection alarm operates when the leakage current exceeds 10.0 milliamps,which is a fixed value that is set by the equipment manufacturer.

7d. The charger overvoltage alarm setpoint should operate at +/- 10% of the nominal cellvoltage, as recommended by the charger manufacturer.

7e. The enclosure overtemperature alarm is + 10% , - 0% of the manufacturer's statedoperating temperature.




8. Inspect the battery room door and ensure that it opens outward and away from thebatteries to facilitate easy exit in the event of an emergency.

9. Verify that battery cables are installed in accordance with the NEC NFPA 70. Batterycables should be installed neatly and properly. Verify that the cable AWG size andinsulation are in accordance with the ampacity of the battery system.

10. The battery output circuit breaker should be equipped with a low voltage shunt trip devicethat will cause the circuit breaker to open if the battery voltage drops to a value 5% belowthe battery final voltage. This circuit breaker undervoltage device should be tested toconfirm that it operates properly.




GLOSSARY

battery One or more electrochemical cells that are lined together toprovide a direct current output. Several cells are normallyconnected in series to provide the desired nominal voltage of adc system.

battery charger An electrical device that is designed to convert an ac input to aDC output for the purpose of charging electrochemical cells.

cell A container that is constructed to house the active plates andelectrolyte solution that are necessary to maintain anelectrochemical reaction that delivers direct current at itsterminals.

cell voltage The voltage that is measured at the terminals of anelectrochemical cell. The cell voltage can be an indication of thestate of charge of some types of cells.

cycle service A duty cycle that is characterized by frequent and usually deepdischarge sequences, such as motive power applications.

electrolyte A liquid mixture that is used in electrochemical cells to conductthe migration of charges between the plates of the cells. Theelectrolyte for lead-acid cells consists of a solution of sulfuricacid and water; the electrolyte for Ni-Cad cells consists of asolution of potassium hydroxide and water.

energy density A ratio of the energy that is available from a battery or cell to itsvolume (Wh/L) or weight (Wh/kg).

equalize charge An amount of charging voltage and current that are sufficient torestore all the cells of a battery to an equal state of charge.

flame arrestor A device that is used to allow generated gases to escape fromelectrochemical cells and to prevent a spark or flame fromentering the cell and possibly causing an explosion.

float service A method of maintaining a cell or battery in a charged conditionby continuous, long-term, constant voltage charging at a levelsufficient to balance self-discharge.




freshening charge The charge that is applied to a new battery after it has beenreceived and filled with electrolyte. Flooded-plate-types ofbattery cells are typically shipped in a dry charged condition.

hydrometer A device that is used to measure the specific gravity of anelectrolyte in an electrochemical cell.

intercell connectors Rectangular metallic links that are designed to connect adjacentcells to one another in a battery. These links are commonlymade of lead-plated copper for lead-acid cells or of stainlesssteel for Ni-Cad cells.

memory effect A phenomenon in which a cell is operated in successive cycles tothe same but less than full depth of discharge. When a battery isrepeatedly cycled to less than full depth, it temporarily loses therest of its capacity at normal voltage levels. This phenomenonnormally applies to Ni-Cad cells only.

Plante cell A specific type of lead-acid cell in which the active materials areformed directly from a lead substrate by electrochemicalprocessing. Cells of the Plante design provide long service life,low positive plate growth, and very high reliability whencompared to other types of lead-acid cells.

power density The ratio of the power that is available from a battery or cell toits weight (W/kg) or volume (W/L).

specific gravity The ratio of the weight of an electrolyte solution compared towater. For example, an electrolyte solution that has a specificgravity of 1.215 has 1.215 times the density of water. Thespecific gravity is an indication of the state of charge of certaintypes of electrochemical cells, such as lead-acid cells.

VPC (voltage per cell) This term is used to indicate the average voltage that is availableat the terminals of an individual cell. VPC may be determinedby dividing the total battery voltage by the number of cells in thebattery.

Documents

Commissioning Systems, Batteries and Battery Charger