Virtual Labs

Control of Bus Voltages Through Onload Tap Changes

The transformer works on principle of ___________ .

a: Self-induction Explanation

Explanation

b: Mutual induction Explanation

Explanation

c: Both Self-induction and Mutual induction Explanation

Explanation

d: None Explanation

Explanation

DC supply __________ be used for the transformer.

a: Can Explanation

Explanation

b: Connect Explanation

Explanation

c: Both Can and Connect Explanation

Explanation

d: None Explanation

Explanation

The ratio of secondary induced emf to primary induced emf is known as _________ .

a: Voltage transform ratio Explanation

Explanation

b: Current ratio Explanation

Explanation

c: Power ratio Explanation

Explanation

d: All Explanation

Explanation

Current ratios are in _________ of the voltage ratio.

a: Direct ratio Explanation

Explanation

b: Inverse ratio Explanation

Explanation

c: Both Explanation

Explanation

d: None Explanation

Explanation

Instrument Transformer are used because

a: It is cheap Explanation

Explanation

b: It provides more safety Explanation

Explanation

c: It is not practicable to connect instruments and meters directly to the lines in high voltage circuits Explanation

Explanation

d: Both it provides more safety and it is not practicable to connect instruments and meters directly to the lines in high voltage circuits Explanation

Explanation

A potential transformer is a ___________

a: Step up transformer Explanation

Explanation

b: Step down transformer Explanation

Explanation

c: Both Step up transformer and Step down transformer Explanation

Explanation

d: None Explanation

Explanation

A current transformer is a ________

a: Step up transformer Explanation

Explanation

b: Step down transformer Explanation

Explanation

c: Both Step up transformer and Step down transformer Explanation

Explanation

d: None Explanation

Explanation

In a power transformer, stepping down from 33kV to 11kV on load tap changes is provided along with 16 steps with 1.25% voltage changes in each step and a constant secondary voltage of 11kV is required. If the primary voltage changes from 33kV to 29.5kV then

a: The taps should be lowered 5 times Explanation

Explanation

b: The taps should be lowered 6 times Explanation

Explanation

c: The taps should be lowered 11 times Explanation

Explanation

d: The taps should be lowered 9 times Explanation

Explanation

a: The taps should be lowered 4 times Explanation

Explanation

b: The taps should be raised 4 times Explanation

Explanation

c: The taps should be raised 2 times Explanation

Explanation

d: The taps should be raised 1 times Explanation

Explanation

The current transformer ratio is not equal to the ratio of secondary to primary turns.

a: The above statement is false Explanation

Explanation

b: The above statement is false, because of the effect of magnetizing current Explanation

Explanation

c: The above statement is true, because of the effect of magnetizing current Explanation

Explanation

d: None Explanation

Explanation

Advantage of using instrument Transformer is

a: Standard rated instruments may be used easily Explanation

Explanation

b: It provides safety for operating personal Explanation

Explanation

c: Both standard rated instruments may be used easily and it provides safety for operating personal Explanation

Explanation

d: None Explanation

Explanation

Potential transformers are carefully designed to ensure

a: Minimum variation of voltage ratio with load and minimum phase shift between input and output voltages Explanation

Explanation

b: Minimum variation of voltage ratio with load and maximum phase shift between input and output voltages Explanation

Explanation

c: Maximum variation of voltage ratio with load and maximum phase shift between input and output voltages Explanation

Explanation

d: Maximum variation of voltage ratio with load and minimum phase shift between input and output voltages Explanation

Explanation