Electrical Measuring Instruments/ Troubleshooting Flashcards Preview

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Flashcards in Electrical Measuring Instruments/ Troubleshooting Deck (26)
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1

Voltage, resistance and power all relate to:

The flow of current

2

The definition of full-scale current

The amount of current that must flow through a meter coil to cause a full scale deflection

3

Define: Meter sensitivity

Reciprocal value of [full scale current], represents total amount of resistance for each volt needed to provide full scale current

4

The amount of current required to give a full deflection on a meter is dependent on

scale that the meter is set to

5

A meter that requires 1 milliamp of current to provide full scale deflection requires ____ ohms or resistance

1,000 ohms

6

The function of the meter sensitivity resistance

Limits the current through the meter to the [full scale current]

7

The total resistance of a meter is termed

meter resistance

8

If the range of current to be measured is greater than the full scale current of a meter, what is installed and how is it installed?

Shunt, installed in parallel

9

Basic description of a shunt installed in parallel to a meter

A resistor which increases the amount of current the meter can measure

10

The type of ohmmeter used to measure very low resistances such as magneto coils

shunt-type ohmeter

11

The basic operation of a Megohmeter (megger)

Hand cranked generator allows the megger to produce several hundred volts

12

Multimeter resolution reffers to

How small a measurement the meter can make

13

Digital multimeters display the _____ of AC voltage waves

RMS values (equivalent DC value)

14

2 things the continuity function on a multi-meter can be used to detect

1. Distinguish good/bad fuses
2. Distinguish good/bad switches

15

What is considered to be zero reference for voltage during troubleshooting ?

Ground

16

When a voltmeter is placed across an open component in a series circuit, what the multimeter reads

Battery or applied voltage

17

The 3 RULES to apply to troubleshooting circuits

1. Make a measurement ONLY if you know what the good measurement will be
2. Make as few measurements as possible
3. Select the best tool for the job at hand

18

The measuring device that does not require the circuit to be opened in order to take a current reading

Current probe

19

Measuring voltage across an open component in a series circuit reads

Supply/source voltage

20

Measuring voltage across all other components in a series circuit except the defective component reads

zero

21

Measuring voltage across a shorted component in a series circuit reads

zero

22

Measuring voltage across an all other components in a series circuit other than the shorted component reads

higher than normal voltage

23

Measuring voltage across all branches of a parallel circuit in a short reads

zero

24

Measuring voltage across all branches of a parallel circuit if one branch is open reads

Source/supply

25

Measuring resistance across an open component reads

Infinite

26

The first step in troubleshooting using an ohmeter

ISOLATE the component