Basic Test Equipment

Question 1

By measuring the amount of _______, all basic ___ electrical measurements can be made

Answer 1

current

DC

Question 2

Although a meter actually measures current, how can a meter scale be calibrated?

Answer 2

In units of voltage.

Question 3

What are the 3 basic meter movements used in analog meters?

Answer 3

1. Moving Coil
2. Taut-Band
3. Moving Iron

Question 4

What is the most common meter used and why?

Answer 4

The moving coil because it is accurate and rugged.

Question 5

Why is the taut-band movement is basically more sensitive and durable a than the original pivot type?

Answer 5

Because friction in the movement is reduced nearly to zero.

Question 6

Ohms-per-volts sensitivity is defined as the amount of __________ that must be placed in ______ with meter movement to limit the _______ through the meter movement to the amount required for full-scale __________ with one volt applied

Answer 6

resistance
series
current
deflection

Question 7

How is an ammeter placed on the wire through which the current(AC or DC) is flowing?

Answer 7

In series, always.

Question 8

To be safe, how should you set the full scale current on an ammeter?

Answer 8

Set it several times larger that the expected current, and then slowly increase the meter sensitivity to the appropriate scale.

Question 9

Why is the variable resistor on an ohmmeter adjusted to zero?

Answer 9

To allow for the expected loss of the battery.

Question 10

What is the the most important precaution before taking a resistance reading?

Answer 10

Be sure power is off to the circuit being tested.

Question 11

What is the wiggins tester basically used for and in what range? Are there any limitations?

Answer 11

It’s used as a voltage tester in the 120 - 600 volt range AC or DC for comparative measurement & live/dead checks
It is limited to 50 to 60 Hz AC.

Question 12

What is a Phase Rotation meter purpose and is it 100% accurate?

Answer 12

It is used to identify phase sequence but not necessarily to predict the direction of rotation.

Question 13

On an ammeter, how large a diameter of conductors does the jaw permit to measure?

Answer 13

Up to two inches.

Question 14

When current through a wire is very small what can you do to get a good read?

Answer 14

Loop the wire through the clamp jaws and then divide the current read by the number of loops.

Question 15

Can you measure current with a clamp-on meter on more than one phase?

Answer 15

No. One phase at a time only.

Question 16

What are the ranges on a clamp-on meter for AC?

Answer 16

1 - 999 Amps

Question 17

What is a Wheatstone bridge most widely used for?

Answer 17

For the precision measurement of resistance.

Question 18

What is the main limiting source of error of the Wheatstone bridge?

Answer 18

The inaccuracy in the three know resistors making up the bridge.

Question 19

What should the insulation resistance be for newly installed equipment when testing with the Megger with what minimum?

Answer 19

Approx. 1 MΩ for 1,000 volts of operating voltage.

A minimum of 1MΩ.

Question 20

What is the useful ohms range for the Megger?

Answer 20

10,000 ohms to 200MΩ.

Question 21

On a Megger, all readings should be corrected to a ______ reference ___________, so that a fair comparison may be made.

Answer 21

common

temperature

Question 22

When using a hand-cranked megohmeter, when should the readings be taken?

Answer 22

While still cranking at rated speed.

Question 23

For the megohommeter, the Time-Resistance-Method is fairly independent of ___________, is performed by taking __________ readings at ________ times.
Test by this method are sometimes referred to as __________ _____.

Answer 23

temperature
sucessive
specific
absorption tests

Question 24

Can you connect a Megger tester to energized lines or equipment?

Answer 24

NO, never

Question 25

What two functions is test equipment generally used for?

Answer 25

1. Troubleshoot

2. Calibrate electrical equipment