Power Quality Fundamentals and Monitoring

Power Quality Fundamentals and Monitoring

Ross M. IgnallSystems Applications Manager,

[email protected]

What We Will Cover…

- Defining Power Quality and Reliability

- PQ References & Fundamentals

- Monitoring, Measuring High Reliability

Facilities

- Case Studies

WPT

Power Monitoring Hardware Devices•measure and monitor power

Aggregation of Distributed Generation•load curtailment of power sales

Data Acquisition Devices•measures physical processes

Software andConsulting Services•power quality and distributed generation

Defining Power Quality & ReliabilityDefining Power Quality & Reliability

What is a Power Quality Problem?

“Any occurrence manifested in voltage,

current, or frequency deviations that

results in failure or mis-operation

of end-use equipment.”

What Does That Mean?

It’s dependant on your susceptibility.

Given the quality of supply do I have

to worry about problems with my

equipment or systems?

What You Should Be Asking…

What is my susceptibility to power problems?

What is my economic exposure to such problems?

$$$$

Types Of Power Quality Problems

Who’s Problem Is It?

Neighbor8% Other

3%Customer 12%

Utility17%

Natural60%

Customer’s Perspective*

* Georgia Power Survey

Who’s Problem Is It?

Utility Perspective*

* Georgia Power Survey

Other0%

Neighbor8%

Customer25%

Utility1%

Natural66%

The Big Picture

It’s the complete electrical environment,

not just the quality of supply

What You Should Be Asking…

Be Proactive!

Does my power system have the

capacity for my present needs?

How about future growth?

An Analogy…

“Just because I have blank checks doesn’t mean that I have money in

the bank to cash them”

Ron Rainville, COO, US Data Centers

Some FactoidsSome Factoids

$50 billion per year in the USA is lost as a result of power

quality breakdown.SOURCE: EPRI, 2000

Half of all computer problems and one-third of all data loss can be traced back to the power line.SOURCE: Contingency Planning Research, LAN Times

Sandia National Laboratories estimates power quality and reliability problems cost US businesses approx. $150 billion annually in lost data, materials and productivity—60% are sags

In 1999, the amount lost as a result of power quality in the US was five times the amount spent on power quality worldwide

Power Quality Factoids

…The data center houses 45,000 square-feet of computer floor

space. In one database, the company has consolidated $1.6 trillion of life insurance information.Energy Decisions, June 2001

During power supply shortages, utilities are generally permitted to have line voltage reductions, so-called “brown outs,” to cope with seasonal power demands…But if equipment is already operating on the low end of nominal voltage then the brown-out may cause excessive heat dissipation in motors and electronic equipment. Building Operation and Management, May 2000

Power Density Factoids

Traditional data center or large office building – 20-30 W/sq. ft., Internet Data Center, on-line brokers, web hosts – 100-150 W/sq. ft.

A web-enabled Palm Pilot requires as much electricity as a refrigerator

Mark Mills

Transformation: Former 16 story Macy’s building used to consume 10 W/sq. ft. Now a telecommunications hotel that according to the utility could require 50 W/sq. ft.

NY Times, July 3, 2000

Costly Downtime!

Industry Avg cost of downtime ($/hr)

Brokerage $6,450,000Credit Card $2,600,000Pay Per View $150,000Home Shopping $113,000Catalog Sales $90,000Airline Reservations $90,000Tele-Ticket $69,000Package Shipping $28,000ATM Fees $14,400

Source: 7x24 Exchange

Introduction to Power Quality

Power Grid Review

GENERATOR13.8kV-24kV

TRANSMISSION115k-765kV

DISTRIBUTION34.5k-138kV4k-34.5kV12,470Y/7200V CONSUMER

4160Y/2400480Y/277V208Y/120V240/120V

LOAD

Generation

50/60hz ‘Pure’ Sine Wave Various Voltages Types

Chemical Mechanical Nuclear Solar

Transmission

Those big towers Voltage High Current Small Efficiency of Transmission

Power Delivered to the Load Power Supplied From Generator

Distribution

Typically 13kV Commercial/Industrial - Three Phase, 480/277V Residential - Split Phase

480V480V

480V13kV

Single Phase Circuit Diagram

LOAD

V lineIs

Vn

Can Wiring and Grounding Affect Power Quality?

“That’s one of the things about living in an old house that drives me nuts. Never enough outlets!”

ACTUAL SINGLE PHASE CIRCUIT DIAGRAM

LOAD

Vpcc Vdp V line

L2 R2L1 R1

L3 R3

L5 R5

L4 R4

L6 R6

Is

I n1l n2

I g2 l g1

Vn

Vg

Sources Of Power Problems

Referenced at the utility PCC (point of common coupling)

Utility lightning, PF correction caps, faults,

switching, other customers

Internal to the facility individual load characteristicswiringchanging loads

Power Quality References & Terms

IEEE Standards Coordinating Committee

• SCC-22• Oversees development of all PQ standards in the

IEEE• Meet at both Summer and Winter Power

Engineering Society meetings• Coordinate standards activities• Progress reports• Avoid overlap and conflicts• Sponsors task forces to develop standards

1433 Task Force to pull together terms. IEEE & IEC

IEEE Standard 1159-1995

Definition of TermsMonitoring ObjectivesInstrumentsApplicationsThresholdsInterpreting Results

IEEE 1159

• 1159.x Task Force Data Acquisition & Recorder Requirements for 1159-1995 Combination of 1159.1 & 1159.2 Coordination with IEC standards (61000-4-30 and revisions) New recommended practice to be developed by July 2001

• 1159.3 Task Force Power Quality Data Interchange Format (PQDIF) Format for the exchange of PQ and other information between

applications Developed by Electrotek Concepts

IEEE 519-1992

Recommended Practice For Harmonics Recommends Limits at the PCC

Voltage Harmonics Current Harmonics

Ongoing work to modify IEEE 519-1992 Limits for within a facility Frequency dependant

International Electrotechnical Commission (IEC)

International standards for all electrical, electronic and related technologies.

IEC Study Committee 77A – Electromagnetic Compatibility, presently 5 Working groups

SC77A/WG 1: Harmonics and other low-frequency disturbances

SC77A/WG 2 : Voltage fluctuations and other low-frequency disturbances

SC77A/WG 6 : Low frequency immunity tests SC77A/WG 8: Electromagnetic interference related

to the network frequency SC77A/WG 9: Power Quality measurement methods

TransientsRMS Variations

Short Duration VariationsLong Duration VariationsSustained

Waveform DistortionDC OffsetHarmonicsInterharmonicsNotching

Voltage FluctuationsPower Frequency Variations

Types Of Power Quality Disturbances (as per IEEE 1159)

Transient Characteristics

High frequency "event"also called Spike, ImpulseRise time (dv/dt)Ring frequencyPoint-on-waveRelative versus Absolute amplitudeMultiple zero crossings

Transients

-200

-100

0

100

200

UnipolarPositive

Negative

NotchingOscillatory

Multiple Zero Crossings

Bipolar

Possible Causes• PF cap energization

• Lightning

• Loose connection

• Load or source switching

• RF burst

Possible Effects• Data corruption

• Equipment damage

• Data transmission errors

• Intermittent equipment operation

• Reduced equipment life

• Irreproducible problems

Transients

A transient power quality event has occurred on DataNode H09_5530. The event occurred at 10-16-2001 05:03:36 on phase A. Characteristics were Mag = 478.V (1.22pu), Max Deviation (Peak-to-Peak) = 271.V (0.69pu), Dur = 0.006 s (0.35 cyc.), Frequency = 1,568. Hz, Category = 3 Upstream Capacitor Switching

Power Factor Correction Capacitor Transient

RMS Voltage Variations

Instantaneous (0.5 - 30 cycles) Sag (0.1 - 0.9 pu) Swell (1.1 - 1.8 pu)

Momentary (30 cycles - 3 sec) Interruption (< 0.1 pu, 0.5 cycles - 3s) Sag Swell

Temporary (3 sec - 1 minute)

RMS Voltage Variations

-200

-150

-100

-50

0

50

100

150

200Sag Swell Interruption

SAGSOURCE GENERATED

DURATION fault clearing schemes may be series of sags (3-4)

MAGNITUDE distance from source feeder topology cause

LOAD CURRENT usually slightly higher, decrease, or zero

PQ Rule

For a source generated Sag, the current usually decreases or goes to zero

PQ Rule

For a source generated Sag, the current usually decreases or goes to zero

SAGLOAD GENERATED

DURATION type & size of load usually single event per device

MAGNITUDE type & size of load wiring & source impedance

LOAD CURRENT usually significantly higher

PQ Rule For a load generated Sag, the current

usually increases significantly.

09/24/00 12:09:54Threshold crossed: 2280.0 VCATEGORY: Short Duration Momentary Sag

Magnitude: 2160.0 VDuration: 2.901 sec.

CHA Volts CHB Volts CHC Volts CHD Volts CHA Amps CHB Amps CHC Amps CHD Amps

Volts

Amps

12:09:54.40 12:09:54.45 12:09:54.50 12:09:54.55 12:09:54.60 12:09:54.65

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

-2500

-2000

-1500

-1000

-500

0

500

1000

1500

2000

Motor Starting - Another Cause of Sags

Timeplot Chart

09/13/96 09:49:00.50 - 09/13/96 09:49:04.00

Min Max Median CHA Vrms 206.11 222.25 219.19 CHA Irms 1.40 847.71 207.16

CHA Vrms CHA Irms 09:49:00.5 09:49:01.0 09:49:01.5 09:49:02.0 09:49:02.5 09:49:03.0 09:49:03.5 09:49:04.0

Volts

205.0

207.5

210.0

212.5

215.0

217.5

220.0

222.5 Amps

0

100

200

300

400

500

600

700

800

900

Motor Starting – Inrush Current with decayWaveforms

AI RMS Norm to Hi at 09/13/96 09:49:00.967

CHA Volts CHA Amps 09:49:00.8 09:49:01.0 09:49:01.2 09:49:01.4 09:49:01.6 09:49:01.8 09:49:02.0 09:49:02.2

Volts

-500

-400

-300

-200

-100

0

100

200

300

400Amps

-2000

-1500

-1000

-500

0

500

1000

1500

SWELLS

Sudden change in load Line-to-ground fault on another phase Often precede a sag

SWELLS when Load Drops Off

10/12/01 14:44:04High Threshold: 12.0 VLow Threshold: 0.0 V

A B C D AB BC CAVrmsmin 460.9 456.9 456.7 0.161 460.9 456.9 456.7

CHA Volts CHB Volts CHC Volts CHD Volts CHA Amps CHB Amps CHC Amps CHD Amps

Volts

Amps

14:44:04.20 14:44:04.25 14:44:04.30 14:44:04.35 14:44:04.40 14:44:04.45 14:44:04.50

-750

-500

-250

0

250

500

750

-3000

-2000

-1000

0

1000

2000

3000

Possible Causes• Sudden change in load current

• Fault on feeder

• Fault on parallel feeder

Possible Effects• Process interruption

• Data loss

• Data transmission errors

• PLC or computer misoperation

• Damaged Product

Voltage Variations Sags/Swells

• CBEMA• ITIC• Equipment Susceptibility• 3-D Mag-Dur• DISDIP

Magnitude & Duration Visualization

IEEE 446 - 1995 Limits

Information Technology Industry Council (ITIC) Curve

Another Use of ITIC Curvebut vendor had tighter tolerances for outputs

Another Perspective – 3D Mag-Dur Histogram

11223

4567

8910

11

Frequency

• Usually not the utility• Sources of frequency problems

Co-gen UPS Engine generator systems

• Clocks run fast

Harmonics

Event waveform/detail

Waveform event at 10/14/93 11:19:27.75

CHD Amps 11:19:27.84 11:19:27.86 11:19:27.88 11:19:27.90 11:19:27.92 11:19:27.94

Amps

-4

-3

-2

-1

0

1

2

3

4dx=00:30:08

Event waveform/detail

Total RMS: 1.44 AmpsDC Level : -0.04 Amps

Fundamental(H1) RMS: 0.48 AmpsTotal Harmonic Distortion (H02-H50): 246.72 % of FNDEven contribution (H02-H50): 73.96 % of FNDOdd contribution (H03-H49): 235.38 % of FND

Waveform event at 10/14/93 11:19:27.75

CHD Amps Thd H02 H04 H06 H08 H10 H12 H14 H16

% of FND

0

50

100

150

200

250

An integer multiple of the fundamental frequency

Fundamental (1st harmonic) = 60hz2nd = 120hz3rd = 180hz4th = 240hz5th = 300hz

…

What is a harmonic?

Linear Voltage / CurrentNo Harmonic Content

voltage

current

Non-Linear Voltage / CurrentHarmonic Content

voltage

current

NEC 1996: Non - Linear Load

"A load where the waveshape of the steady-state current does not follow the

waveshape of the applied voltage."

voltage

current

Harmonics

Steady state distortionPeriodic or continuous in nature

IEEE-519-1992 / US harmonics IEC 61000-3-2&3 European harmonic limits

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

0.02 0.03 0.05 0.07 0.08

Amps

Time (Sec)

Harmonic Measurements

Total Harmonic Distortion (THD) Ratio, expressed as % of sum of all harmonics to:

Fundamental (THD) Total RMS Load Current (I TDD only)

Individual Harmonics 2, 3, 4, 5, 6…50+ Fourier Transform, FFT, DFT

Interharmonics Content between integer harmonics

Composite WaveformEvent waveform/detail

CHA Volts 05:35:31.26 05:35:31.28 05:35:31.30 05:35:31.32 05:35:31.34 05:35:31.36 05:35:31.38 05:35:31.40

Volts

-50000

-40000

-30000

-20000

-10000

0

10000

20000

30000

40000

50000

Harmonic SpectrumEvent waveform/detail

Total RMS: 24882.56 VoltsDC Level : 880.46 Volts

Fundamental(H1) RMS: 24725.89 VoltsTotal Harmonic Distortion (H02-H50): 10.60 % of FNDEven contribution (H02-H50): 7.97 % of FNDOdd contribution (H03-H49): 6.99 % of FND

CHA Volts Thd H05 H10 H15 H20 H25 H30

% of FND

0.0

2.5

5.0

7.5

10.0

12.5

PQ Rule

Even harmonics usually do not appear in a properly operating power system.

Symmetry Positive & Negative halves the same:

Only odd harmonics.If they are different: Even & Odd

harmonics

Possible Effects• Overload of neutral conductors

• Overload of power sources

• Low power factor

• Reduced ride-through

Possible Causes• Rectified inputs of power supplies

• Non-symmetrical current

• Intermittent electrical noise from loose connections

Harmonics (sustained)

Electronic Loads Cause Excessive Neutral Currents

Phase A (50 Amps)

Phase B (50 Amps)

Phase C (57 Amps)

Neutral (82 Amps)

ElectronicLoads

Additive Triplen Harmonics

Equipment Susceptibility

Least Susceptible Electrical Heating

Oven Furnaces

Most Susceptible Communications Data Processing

Zero crossing Clock Circuits Transformers, Motors, other inductive loads

IEEE 519 Harmonic Limits

Limits depend on ratio of Short Circuit Current (SCC) at PCC to average Load Current of maximum demand over 1 year

For example, Isc/IL < 20, odd harm <11 = 4.0% Isc/IL 20<50, odd harm < 11 = 7.0% Isc/IL >1000, odd harm > 35 = 1.4%

IEEE 519 Harmonic Limits

Voltage Harmonic Limits depend on Bus V

For example,69Kv and below, ind. harm = 3.0%69Kv and below, THD= 5.0%

161kv and above, ind.harm = 1.0%161kv and above, THD = 1.5%

Harmonics Demo Tool

CH A CH B CH C Neutral 0 50 100 150 200 250

-150

-100

-50

0

50

100

150

Voltage Unbalance

Several ways to calculate Small unbalance can cause motor overheating (3% results in 10% derating)

Caused byUnequal loadingUnequal source impedanceUnequal source voltageUnbalanced fault

Voltage Fluctuation

Voltage Fluctuation

Amplitude variation 1-30 Hz Extent of light flicker depends on

type of lightsamplitude and frequency of variationperson's perception

Typical causesHigh current loads, like arc furnacesWindmill-generated power

Voltage FlickerTimeplot

02/07/2002 00:05:00

CHA VPst() CHB VPst() CHC VPst() 02/06/2002 02/08/2002 02/10/2002 02/12/2002 02/14/2002 02/16/2002 02/18/2002 02/20/2002

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

How Many Can You Find?

Suggested References

[1] Electrical Power Systems Quality, R.C. Dugan et al, McGraw-Hill, 1996 [2] Handbook of Power Signatures, BMI, 2nd Edition, 1993 [3] IEEE Standard 1159-1995, IEEE Recommended Practice for Monitoring Electric Power Quality [4] IEEE Standard 519-1992, IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems [5] IEEE Standard 1250-1995, IEEE Guide for Service to Equipment Sensitive to Momentary Voltage Disturbances [6] IEEE Standard 446-1995, IEEE Recommended Practice for Emergency and Standby Power Systems for Industrial and Commercial Applications [7] IEEE Standard 142-1991, IEEE Recommended Practice for Grounding of Industrial and Commercial Power Systems [8] Federal Information Processing Standards Publication (FIPS PUB 94) Guideline on Electrical Power for ADP Installations

Case StudyCase Study

Laser PrinterLaser Printer

TIMEPLOT - LINE VOLTAGE vrs NEUTRAL-GND VOLTAGE

Vl-n= 120 --> 108

Vn-g = 0 --> 6V

45 seconds

SAG when heater turns on

V l-n

I load

V n-g

Overlay Waveforms - Heater turn on

Current Waveform - heater on

HARMONIC DISTORTION - heater on

4.4%

Harmonics V l-n

Harmonics I load

Harmonics V n-g

2.3%

Waveforms when heater turns off

V l-n

I load

V n-g

Harmonic Distortion - Idle

94%

Harmonics V l-n

Harmonics V n-g

Harmonics I load

2.3%

Current With Printer Idle

EQUIVALENT CIRCUIT

121 Vac

0.47 ohms

Idle Load202 ohms

+

-

Source Impedance

I LoadV Load

Heater Load11.9 ohms

0.6A @ 121V 10.4A @ 117V

V n-g+

-

OBSERVATIONS and PARAMETERS

Nearly Sinusoidal Current– Low Harmonic Distortion (4%)

Voltage and Current In-phase– Power Factor Near One

Flat-topping of Voltage when Idle Corresponds with Current Pulse

OBSERVATIONS and PARAMETERS

Line Voltage Negative Transient on Turn on– Corresponds with Vn-g Positive Transient

Nearly Constant Repetition Rate

SIMILAR SITUATIONS

•Coffee Pot•Coke Machine•Heat Pump

Monitoring, Measuring & Managing Monitoring, Measuring & Managing High Reliability Facilities High Reliability Facilities

Why Monitor Your Electrical Supply?Why Monitor Your Electrical Supply?

Paradigm Shift?

You may no longer be able to rely You may no longer be able to rely on the utility to be your primary on the utility to be your primary source of power!source of power!

Be Prepared

Why Monitor Your Electrical Supply?

• Quality of supply is of paramount importance

• Huge investment in protection & mitigation is not a guarantee!

• You have a high economic exposure

• Your facility is core to your business or maybe is your business

• You already monitor other critical items

• Your electrical environment is just as important

• You need to balance your needs with available supply

• Loading, cost allocation, etc

You May Already Monitor Your Facility

• Traditional Data Center

• Building Management Systems (BMS), Human Machine Interface Software (HMI)

• Wonderware, Sitescan, ALC, Datatrax, etc

• Via Bacnet, Lonworks, Incomm, modbus, etc

• Internet Data Center

• Network Operations Center (NOC)

• HP Open View, etc

• Via SNMP

What You May Already Monitor

• Traditional Data Center• UPS - On Bypass, other alarms

• Traditionally do not measure quality• Sub Metering • HVAC, Fire, Security

• Internet Data Center• Network/System Health• HVAC, Fire, Security

• Electrical Supply is often overlooked• Quality of supply, Energy/cost allocation

• Power monitoring can interface with existing systems for single point alarming, logging, etc…

Approaches to Power Monitoring

Reactive — Forensic, after the fact.

Proactive — Anticipate system dynamics

Be Proactive!

Reactive Approach

• Problem Solving, hopefully you’ll find it!

• Portable instrumentation typically used

Proactive Approach

• Permanently installed monitoring systems

• Anticipate the future – on-line when trouble occurs

• Monitor system dynamics

• Preventive Maintenance, Trending, identify

equipment deteriorationBe Proactive!

Power Quality vs. Power Flow

• Power Quality Monitoring - Quality of SupplyQuality of Supply• Monitor for harmful disturbances, harmonics, etc• Microsecond, Sub-Cycle Measurements• In close accordance with IEEE 1159 & IEC

• Power Flow Monitoring - How much, cost, when & where?How much, cost, when & where?• Energy & Demand, Measured over seconds• Be Careful! False sense of security

• Blind to common PQ problems

Use a PQ instrument for PQ monitoring!

Comprehensive Power Monitoring

• Combined Power Quality and Flow

• Monitor PQ at critical locations• Utility service, UPS, PDU’s, loads• Energy provided along with PQ

• Monitor Energy at less critical locations & individual loads

• Loading• Sub Metering• Cost Allocation, etc…

Emerging Technologies

• Reduced Cost

• Web monitoring • Networked systems• Native web access

• Maximize Assets• Sharing of information among systems and groups within the organization

• Expert Systems

• Enterprise Systems• Pull together various separate systems

Enterprise Systems

• Traditional Facilities• Power monitoring system interfacing with building management, HMI or other systems• Notification, metering, trending• OPC. Modbus, e-mail

• Internet Data Center • Interface with Network Operations Center (NOC)• Notification, metering, trending• Simple Network Management Protocol (SNMP)

Expert Systems

• Reduced budgets means less people!• Less expertise

• Analysis of Data in order to Identify Problems

• Automatic, no user intervention, results embedded in data

• Identify certain disturbances and directivity.• Upstream or downstream

• Answers Questions Such As…• Was that Sag from the utility or within my facility?

Expert Systems

• UPS Performance Verification• Correlation of Input vs. Output

• Verify continued performance over time

• Proactively identify downstream problems

• Monitor UPS status via analog/contact inputs

• Remotely access UPS status signals

• Compare recorded data to UPS status

Expert Systems

Expert Systems

Automatically Identifies the Transient as a Capacitor Switching Operation

Where To Monitor?• Utility Service Entrance

• Evaluate your energy provider• Monitor redundant feeds

• UPS Output• Is your UPS working as designed?• Evaluates critical bus as problems could be downstream

• PDU/Distribution• Provides the ability to identify the source of a problem. Why did that breaker trip?• Loading/Cost allocation

• Actual loads


DHL Airways Call Center

• Tempe AZ

• Services DHL customers nationwide

• Newly Constructed, went online in June 2000

• Toshiba 7000 Series UPS• Three 300KVA parallel redundant units

• Facility manager has nationwide responsibilities

• Current Expansion Plans

DHL Objectives

• Benchmark performance

• Ensure future reliability

• Easily troubleshoot any problems that may occur

• Automatic notification

• Remotely monitor over DHL network

• Since the facility is new and due to its critical nature, monitoring approach was very proactive

DHL Monitoring System

• Monitoring Points• UPS Input (Utility Supply)• UPS Output (Critical bus)

• Connected to DHL Intranet

• Dial-up modem connection

• Web browser access from anywhere within DHL

• Automatic E-mail notification

• Web browser access from anywhere with a dial-up connection

Known Problems?

• None!

• Facility operating as planned

• No Outages or other major problems identified

• No UPS Alarms

Utility Supply

50+ Disturbances in the first few months

UPS Output

No disturbances

Utility Monitoring Summary

• Uncovered problems with the utility supply• 50+ disturbances recorded over a 2 month period. • Sags, transients, waveshape distortion

• Results reported to the utility, they did not know

• Utility investigation• Faulty relay caused the majority of the disturbances. Corrected

UPS Output Monitoring Summary

• No disturbances on the conditioned UPS output

• Output regulated to within manufacturers specifications

• UPS mitigated many disturbances on the utility feed

• Did what they paid for

• Justified the investment

Conclusion

• Being proactive uncovered problems with the utility supply that required correction

• Continuous monitoring proved power conditioning equipment worked as design and to manufacturer’s specifications. Protected loads were unaffected

• Provided justification to management for power monitoring systems at other key facilities

• Load profiling helping to determine power requirements of a planned expansion


Major Financial Institution

• New York City

• Worldwide company with several facilities in NY & NJ• 3 UPS Modules

•2 static, 1 rotary

Problem

• Utility Sag• Damaged elevator controls• No UPS alarms• No reported problems with critical systems

02/19/2002 00:29:29.26

PMODULEINPUT

Temporary Sag

Rms Voltage AB

Mag = 366.V (0.76pu), Dur = 3.300 s, Category = 2, Upstream Sag

02/19/2002 00:29:29.26

SYSA Input

Temporary Sag

Rms Voltage AB


02/19/2002 00:29:29.26

SYSB Input

Temporary Sag

Rms Voltage AB


Utility Sag

Utility Supply RMS Trend

Utility Supply Waveforms

Corresponding UPS Swell

Utility Supply

UPS Output

UPS Swell

Conclusion

• Utility sags damaged elevator controls. • Corresponding UPS Swell coincident with Utility return to normal.• Cause of Swell being investigated…• Possible effects of Swells:

• Damaged power supplies and other devices.• Without monitoring would have never seen this. The next time it could be worse.


Federal Aviation Administration

Air Route Traffic Control Center (ARTCC)

Monitoring System

Simplified Air Traffic Flow

Tower

TRACON

ARTCCARTCCARTCC

TRACON

Tower

Your Flight

FAA’s Objectives

• Monitor critical points throughout each ARTCC

• Determine present status of each ARTCC Facility • Is the electrical supply operating within design parameters?

• Catch problems before they occur• Change approach from Reactive to Proactive

• Correlate power quality to status indicators, panel

meters, transfer switch positions, etc

FAA’s Objectives

• Benchmark long term performance in order to improve reliability

• Compare measured parameters to simulations

• Have web browser access from anywhere within the FAA system

• Local ARTCC personnel• OKC Airway Operational Support (AOS) personnel

Monitoring System

• Monitor 15 points for quality of supply & energy• Utility Service• Generators• UPS’s• Key distribution points• Critical Power Centers

• In parallel monitor other data such as• Transfer switch & breaker positions• Panel meters• Misc indicators

• Web based access to each site via intranet

Initial Results

• Key points operating out of design specs• Ex: Adjust transformer taps

• Routine maintenance not always performed as per procedures

• Wiring inconsistent with drawings

Power Quality Fundamentals and Monitoring

Thank You!Thank You!

Questions?Questions?

Ross M. IgnallSystems Applications Manager,

[email protected]

Documents

Power Quality Fundamentals and Monitoring