transformer operation

Question 1

The principle by which a transformer induces voltage from one winding to another is known as ? .

Answer 1

electro magnetic induction

Question 2

There will be no current present in a transformer unless there is a load connected to the secondary.

Answer 2

false

Question 3

The process that limits current flow on the primary winding is self- ?

Answer 3

induction

Question 4

AC windings will usually burn out if connected to a DC circuit.

Answer 4

true

Question 5

The higher the number of turns on the secondary side, the lower the output voltage.

Answer 5

false

Question 6

The voltage change from primary to secondary is governed by the ratio of turns in the primary coil to the turns in the secondary coil.

Answer 6

true

Question 7

Of the three ratios governing transformer operation, ? is in the reverse order to the other two.

Answer 7

current

Question 8

The product of the primary voltage and current is equal to the product of the ?

Answer 8

secondary current and voltage

Question 9

? is the number of turns in the primary winding to the number of turns in the secondary winding.

Answer 9

turns ratio

Question 10

The voltage ratio of a transformer is the effective voltage of the primary to the potential voltage of the secondary.

Answer 10

false

Question 11

If the turns ratio is shown as 10:1, it is a step-down transformer. If the ratio is shown as 1:10, it is a step-up transformer.

Answer 11

true

Question 12

How can the primary turns of a distribution transformer be changed?

Answer 12

tap changing switch

Question 13

A tap-changing mechanism works by adding in windings to the secondary side of a transformer.

Answer 13

false

Question 14

When voltage is consistently ? , a company will, as a temporary measure, change the tap setting on the transformers, if the transformers are so equipped.

Answer 14

low

Question 15

Distribution transformers have off-load tap switches, which do not in any way regulate the ? voltage.

Answer 15

secondary

Question 16

Prior to changing taps, recording voltmeters should be set and left to record for at least ?

Answer 16

24 hrs

Question 17

Recording voltmeters should be set at the customer’s service entrance because there may be a ? drop in voltage between the transformer and the customer’s service entrance.

Answer 17

4%

Question 18

An electric provider is allowed to have extreme voltages on a 120-volt service of 106 volts low and ? high.

Answer 18

127 v

Question 19

A potential transformer is safe because it is not used to measure high voltage.

Answer 19

false

Question 20

Current transformers reduce the current being metered to a value that should not exceed ?

Answer 20

5 amps

Question 21

A current transformer should have its ? short-circuited while being installed, or while connected in a circuit with no meter connected to the secondary.

Answer 21

secondary

Question 22

With the secondary open, if a CT is energized, the high voltage may puncture the insulation and cause injury to personnel.

Answer 22

true

Question 23

Current transformers are installed on single-phase circuits when the current exceeds 400 amperes and on 3-phase circuits when the amperage exceeds ?

Answer 23

200A

Question 24

With the use of CTs and PTs, conventional meters can be used to measure high current and high voltage circuits.

Answer 24

true

Question 25

Michael Faraday discovered the principle of electromagnetic induction.

Answer 25

true