Phase 2 2-2-6

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

127 V

A transformer with 14,400 primary turns and 500 secondary turns produces a secondary voltage of 480 volts. Assuming 100% transformer efficiency, the primary voltage is ?

13,824

The transformer ratio is 10:1. If the secondary voltage is 210 volts, the primary voltage is ?

2,100 V

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

200 A

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

24 hours

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

4%

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

5 A

Given a primary voltage of 2,292 volts; to maintain a secondary voltage of 240 volts, the tap changer should be set to 4.5%, which means that ? of the primary windings are in use

95.5%

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

False

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

False

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

False

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

False

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

False

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

True

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

True

Michael Faraday discovered the principle of electromagnetic induction.

True

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

True

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

True

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

True

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

Turns ratio

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

With a tap changing switch

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

current

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

electro-magnetic induction

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

induction

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

low

The winding that receives the energy is the ? winding.

primary

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

secondary

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

secondary

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

secondary current and voltage