Electrical Measuring Equipment

Question 1

What do all electrical meters have in common?

Answer 1

They all have an internal standard to which measured values are compared.

Question 2

How did digital meters get their name?

Answer 2

Comes from the fact that like a computer, all data is processed as discreet 1’s and 0’s

Question 3

Digital meters all need…….

Answer 3

a signal processor
an analog to digital converter (ADC)
and a readout control

Question 4

All integrating ADC’s use capacitors, they count the time it takes to fill and discharge a cap. to a reference voltage.

Answer 4

True

Question 5

What is resolution in regards to digital meters?

Answer 5

deals with how finely the meter can distinguish between two values.

Question 6

Accuracy in meters in expressed in ……….

Answer 6

a percentage.

Question 7

What is the most common analog meter?

Answer 7

The D’Arsonval movement meter

Question 8

Every digital meter requires an?

Answer 8

Analog to digital converter

Question 9

The advantage of LCD over LED for meters is ……..

Answer 9

lower power consumption

Question 10

Sensitivity of an analog meter is expressed in ……….

Answer 10

ohms per volt

Question 11

What safety feature do meters have to protect the movement meter during switching between ranges?

Answer 11

Make then break switch

Question 12

What will an accurate wattmeter always show you?

Answer 12

The true power consumed.

Question 13

The jaws of a clamp on ammeter act like the secondary of a transformer with the being the primary.

Answer 13

conductor

Question 14

An AC voltmeter has at least one in it.

Answer 14

Diode

Question 15

Hands free voltmeter leads should be used when measuring circuits.

Answer 15

Moderate to high voltage

Question 16

What is the purpose of rectifiers?

Answer 16

Convert AC to DC

Question 17

What is at the end of an ohmeters scale is maximum resistance or……….

Answer 17

infinity.

Question 18

The current flowing through an ohmmeter is very small values.

Answer 18

true

Question 19

A shunt ohmmeter allows for measurements of much smaller resistances.

Answer 19

true

Question 20

Do shorted capacitors exhibit any resistance?

Answer 20

No they are shorted

Question 21

Graphical multimeters ac are capable of displaying…….

Answer 21

Spikes
Surges
sags
high speed transients

Question 22

What can be viewed in TREND mode?

Answer 22

Monitor line voltages for 
sags and surges
battery activity for charging and discharging cycles
AC frequency changes 
intermittent breaks in continuity

Question 23

What is the chief cause for catastrophic meter failure??

Answer 23

Unexpected overvoltage

Question 24

Describe the CAT 1-4 in regards to electrical safety and equipment

Answer 24

CAT 1-very low voltage electronics
CAT 2- protected electronic equip/low voltage 120VAC
CAT 3-big appliances/machinery, MCC, Switchgear 240-480 VAC
CAT 4- Transformer yard, Transmission lines, Generating facility

Question 25

What is needed to measure current greater than 10A with a multimeter?

Answer 25

A current probe of current transformer

Question 26

Inscribed on oscilloscopes is a grid like pattern called a graticule.

Answer 26

Good units have the graticule inscribed on the inside.

Question 27

Oscilliscopes have 2 kinds of sweeps (motion of the light) name them.

Answer 27

Free running ( charge up, discharge down) 
triggered sweep (predermined amount blanked off for accurate measure)

Question 28

What is a dual trace oscilloscope?

Answer 28

It shows two waveforms at once, one above the other and can be produced three different ways.

Question 29

Most oscilloscopes have the ability of interpolation or “fill in” between sample points

Answer 29

T

Question 30

Slope ( which side of the x axis it will flow) and trigger controls (signal amplitude determines display) control when the display will register.

Answer 30

T

Question 31

Circuit loading when measuring with an oscilloscope can be prevented by using a…….

Answer 31

attenuating probe

Question 32

The reference signal jack , used when compensating the probe, delivers a……….

Answer 32

square wave form

Question 33

What causes strong harmonics in the original voltage sign wave in an AC power line?

Answer 33

non linear building loads