CNR S&C ATP — Introduction to Multimeters.pdf

8/14/2019 CNR S&C ATP Introduction to Multimeters.pdf

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Introduction to Multi-meters

Bach Simpson TS111A


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Safety Precaution:

1. Leave TSIIIA Multi-meter on 300 VDC scale to prevent meter damage andpersonal injury if connected to a higher voltage than anticipated.

2. Make sure that appliances and measuring instruments are properly connected to

avoid creating a short.3. The black lead of the meter is ALWAYS inserted into the "COM" jack. The red

lead is inserted into one of the other jacks depending on the type of readingdesired.

4. Always set the selector switch before connecting the leads to the equipment.

5. When not sure of the voltage to be measured, turn the power off beforeconnecting the leads.

6. Do not touch the exposed portion of the leads when the power is on.

Description:

1. Multi-meters are used to measure voltage, amperage, resistance, etc.

2. Two types of Multi-meter are commonly used: 1) Digital meter, 2) Analog:TS111A Multi-meter.

3. Both digital and analog meters have a selector switch to select the type ofmeasurement wanted.

4. We use the TS111A Multi-meter to test the voltage of Primary Cell and Lead Acidand NICAD batteries, while we use the digital meter to test electronic circuits.

5. To measure the resistance we set the meter to the ohms scale.

6. To measure the current we set the meter to the ampere scale.7. To measure the voltage we set the meter either to the DC or AC scale.

8. When not in use, the meter should be set on the 300 VDC scale.


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The Bach Simpson Multi-meter

1. The TS111A multi-meter is used to measure: DC voltages, AC voltages, current,resistance, etc

2. It is the same as the digital meter. Insert leads in proper jacks. Select scale. Take

reading.3. To take an accurate meter reading, look into the mirror mounted behind the

meter movement, adjust your view until the needle covers the needles reflection,this will ensure the scale will be perpendicular to your view.

4. The meter has different jacks (going clockwise):

a. The black lead goes and stays in the COM jack.

b. The jack next to the COM is to read volts, ohms and % on time.

c. The next one is to read up to 6 amps DC.

d. The following is to read up to 30 amps DC.

e. The next is to read max 1.5 amps and min 15 ma (1000 ma = 1 amp).

f. The next is to read up to 30 amps AC.

g. The last one is to read up to 3 amps AC.

5. The black lead is negative and you plug it into the jack marked "COM". The redlead goes into another jack.

Reading an Analog Meter

The meter is most accurate when it is lying horizontal.

The reading is most accurate when the pointer is between the center and the right handportion of the scale.

When not sure of the value to be measured, set the selector switch to the highest rangebefore connecting the leads, and then switch it to the appropriate range.


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Procedure for Measuring Battery (DC) Voltage with the Bach Simpsonmulti-meter

1. Make sure that the black lead of the meter is plugged into the COM (-) jack andthat the red lead is plugged into the V--% (+) jack.

2. Before taking a reading, always set the meter to the highest scale. This willavoid possibly blowing out the meter. We set the meter to the 300 VDC scale,because the batteries produce DC source of voltage. Setting the meter to thewrong scale can damage it.

3. Connect the meter in parallel with the battery. To perform this, connect the blacklead from meter to the black or negative terminal of the battery and red lead tothe red or positive terminal of the battery.

4. If there is no reading on the meter then you set the meter to the next lower scale.

i. If the reading you get is greater that the next lower scale (60, 15, 3,or 0.6), then you have the most accurate reading.

ii. If the reading you get is less than the next lower scale (60, 15, 3, or0.6), then you may lower the scale for a more accurate reading.

5. When you are done, return the meter to the 300 VDC scale.

Procedure for Taking AC Voltage with the TS111A Multi-meter

1. Make sure that the black lead of the meter is plugged into the COM (-) jack andthat the red lead is plugged into the V--% (+) jack.

2. Before taking a reading, always set the meter to the highest scale. This willavoid possibly blowing out the meter. We set the meter to the volts 600 VACscale. Setting the meter to the wrong scale can damage it.

3. Connect the meter in parallel with the equipment. Connect the red lead to thepositive (BX) terminal and the black lead to the negative (NX) terminal of theequipment.

4. This is AC voltage, so you will get the same reading if you connect the leads onopposite terminals. However, it is recommended to connect the leads asdescribed.

5. If there is no reading on the meter then you may set the meter to the next lowerscale.

6. If the reading you get is greater that the next lower scale (150, 15, or 3), then you

have the most accurate reading.

7. If the reading you get is less than the next lower scale (150, 15, or 3), then youmay lower the scale for a more accurate reading.



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Procedure for Taking a (DC) Current Reading, TS111A Multi-meter

1. Make sure that the black lead of the meter is plugged into the COM (-) jack. Thered lead must be connected to the 30 (+) DC AMPS jack. The dial must be set tothe DC AMPS position. You are set to the largest DC AMPS scale.

2. The meter must be connected in series with current flow:

i. Connect the red lead with the positive terminal of the battery, andthe black lead with the positive terminal of the equipment.

OR

ii. Connect the black lead of the meter with the negative terminal ofthe battery and the red lead of the meter with the negative terminalof the equipment.

3. If there is no reading on the meter then you may lower the scale. To lower thescale you must connect the red lead with the 6 AMPS DC jack, and then, ifnecessary, with the 15 - 1.5 ma DC jack and use the dial.

4. If the reading you get is greater that the next lower scale (6 A, 1.5A, 300 ma,60mA, or 15mA), then you have the most accurate reading.

5. If the reading you get is less than the next lower scale (6 A, 1.5A, 300 ma, 60mA,or 15mA), then you may lower the scale for a more accurate reading.

6. When you are done, return the meter to the 300 VDC scale. Return the red leadto the V--% (+) jack.


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Procedure for Taking an (AC) Current Reading with a TS111A Multi-meter

2. Make sure that the black lead of the meter is plugged into the COM (-) jack. Thered lead must be connected to the 30 AC AMPS jack. The dial must be set to the

AC AMPS position. You are set to the largest AC AMPS scale.

3. The meter must be connected in series with current flow:

i. Connect the red lead with the positive terminal of the battery, andthe black lead with the positive terminal of the equipment.

OR

ii. Connect the black lead of the meter with the negative terminal ofthe battery and the red lead of the meter with the negative terminalof the equipment.

4. If there is no reading on the meter then you may lower the scale. To lower thescale you must connect the red lead with the 3 AMPS AC jack.

5. If the reading you get is greater that the next lower scale (3 A), then you have themost accurate reading.

6. If the reading you get is less than the next lower scale (3A), then you may lowerthe scale for a more accurate reading.

7. When you are done, return the meter to the 300 VDC scale. Return the red leadto the V--% (+) jack.


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Procedure for Taking a Resistance Reading, TS111A Multi-meter

Note: The equipment being read must be isolated from all voltage beforebeginning.

1. Make sure that the black lead of the meter is plugged into the COM (-) jack and

that the red lead is plugged into the V-

-% (+) jack.2. Set the meter to the X1 or the X100 scale, depending on the expected reading.

3. Connect the meter leads together and hold down the Push for Ohms button. Wedo this to reset the meter. Using the Adjust Ohms and Percent on Time dial setthe meter to read full scale or zero ohms. Release the button and disconnect theleads.

4. Connect to the resistance to be measured.

Note: If the meter needle moves and the Push for Ohms button isreleased then voltage is present in the circuit. This voltage must beeliminated before a resistance measurement is made, or you willnot be able to take an accurate reading.

5. If the meter does not indicate voltage, then press the Push for Ohms button.Read the resistance on the black Ohms scale. Remember to multiply the valueby 100 if you are set to the X100 scale.

6. The meter must be reset for every resistance reading taken.



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Points of interest on a Bach Simpson TS111A Multi-meter


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Performance exercise

Example

To read the voltage across one track battery cell:

a) Draw an arrow to indicate the range where the selector switch should be set.

b) Use a red marker to color the jack where you would plug in the red lead.

c) What is the voltage displayed on the meter?___1.25VDC__


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1. To read the voltage across one-track battery cell:



c) What is the voltage displayed on the meter?______________________


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2. To read the voltage across a 12v operating battery:





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3. To read a load that may be between 600 ma DC and 800 ma DC:



c) What is the current displayed on the meter?______________________


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4. To read a charge that may be:between 300 ma DC and 1.5 amps DC:





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5. Read the working current of a track relay that may be:around 350 ma DC:




d) What would that current be in amps?____________________________


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6. Read the current of a power switch machine that will be:less than 30 amps DC:





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7. Read the voltage of an AC supply circuit that will be:less than 600 volts AC:





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TS111A Multi-meter - Care

After use, keep the meter in clean, dry and vibration-free location.

If the meter is wet, remove it from the carrying case and thoroughly wipe it clean and

dry.

Dust or debris should be carefully blown or brushed off the meter. Do not press onthe meter window if a plastic shield does not protect it.

The meter must not be transported in any vehicle while hanging by its strap.

The meter should be transported in the passenger compartment of a vehicle. Itshould be placed in a special padded carrying case, or if none is available, onthe seat.

When not used the meter leads must be coiled and the cover must be closed.

When using the meter outdoors in bad weather, protect it with a piece of clear plasticwrap.

After use set the meter to the 300 VDC range. This lessens the chance of carelesslypinning the needle accidentally.


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TS111A Multi-meter - Maintenance

Test leads must be checked at least once a month. Plugs and clips must be secureand in good condition. Leads must have no broken strands and be properlyinsulated. Defective leads must be repaired or replaced immediately.

Meters with cracked or loose "glass" must be sent immediately for repairs.

The screws fastening the meter case together must be kept tight.

The carrying case must be kept in good condition. Temporary repairs can be madeusing strong nylon thread.

One or more fuses should be stored in the meter case. A 500 ma. (1/2 amp) fastblow fuse must be used as a replacement.

Unless otherwise specified, all repairs and adjustments are to be performed at theSignal Repair Shop.

To check the accuracy of the meter, take readings of known values. Should youhave any doubts about the accuracy of a meter, you can check it bycomparing its readings with those of another meter.


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TS111A Multi-meter - Usage

The batteries should be checked at least once every six months. They shouldbe checked for their state of charge, corrosion, and any other defects.

The following methods can be used to check the state of charge of thebatteries:

1.5 V batteryClip the test clip together with the meter set on the x1 Resistance range.

Adjust the "Zero Ohms" control, with the "Push for Ohms" button depressed,until the pointer reaches zero ohms. If the pointer will not move to zero ohmsor will not stay set there, the 1.5-volt battery should be replaced with analkaline battery.

9.8 V or 9 V batteries

Set the range switch to "Set 100" and adjust the "Zero Ohms" control until thepointer reaches 100 on the "Percent On Time" scale. If the pointer will notreach 100, or will not stay set there, the two batteries should be replaced.

For voltage and current measurements, the pointer must idle on zero.

For resistance measurements, the meter must be "zeroed" each time aresistance range is selected.

Before doing a Percent "On" Time measurements, the meter pointer must beset at 100.

For Peak Value measurements, the special "Pointer Stop" must be used.


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Quiz

1. Into which jack do you plug the black lead of the meter?

2. Where do you plug in the red lead of the meter if you have to take a voltagereading?

3. How do you decide to which range to set the meter?

4. If you expect the battery voltage to be less than three volts, what should themeter setting be? On which scale do you take the voltage reading?

5. If you expect the battery voltage to be between 40 and 50 volts, what should themeter setting be? On which scale do you take the voltage reading?

6. If you are not sure what the approximate value of the reading will be, what should

you do?

7. What should the pointer position be for the best reading?

8. What should you do to take good care of the TS111A multi-meter?

9. After using the TS111A multi-meter, to which range should you set it?


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Documents

CNR S&C ATP — Introduction to Multimeters.pdf