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A transformer has a primary winding of 800 turns and a secondary winding of 200 turns. When the load current on the secondary is 80A at 0.8 power factor lagging, the primary current is 25A at 0.707 power factor lagging. Determine graphically or otherwise the no-load current of the transformer and its phase with respect to the voltage.?
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A transformer has a primary winding of 800 turns and a secondary windi...
Problem: Finding the no-load current and its phase with respect to voltage in a transformer with given primary and secondary winding turns and load current.

Solution:

Step 1: Calculate the apparent power on the secondary side of the transformer.

Apparent power on the secondary side, S = V x I
where, V = voltage on the secondary side
and I = load current on the secondary side

Given load current on the secondary side, I = 80 A
Power factor on the secondary side, pf = 0.8 lagging
Hence, cos(φ) = 0.8 and sin(φ) = 0.6
Therefore, voltage on the secondary side, V = I / (pf x √3)
= 80 / (0.8 x √3) = 48.99 V

Apparent power on the secondary side, S = 48.99 x 80 = 3919.2 VA

Step 2: Calculate the apparent power on the primary side of the transformer.

Apparent power on the primary side, S = V x I
where, V = voltage on the primary side
and I = primary current

Given primary current, I = 25 A
Power factor on the primary side, pf = 0.707 lagging
Hence, cos(φ) = 0.707 and sin(φ) = 0.707
Therefore, voltage on the primary side, V = I / (pf x √3)
= 25 / (0.707 x √3) = 14.43 V

Apparent power on the primary side, S = 14.43 x 25 = 360.75 VA

Step 3: Calculate the no-load current of the transformer.

No-load current of the transformer, Io = S / V
where, S = apparent power on the primary side
and V = voltage on the primary side

Given S = 360.75 VA and V = 14.43 V
No-load current, Io = 360.75 / 14.43 = 24.99 A

Step 4: Determine the phase of the no-load current with respect to voltage.

The no-load current of a transformer lags the voltage by a small angle due to the magnetization of the core. This angle is usually denoted by θ or φ.

Given primary current, I = 25 A
Power factor on the primary side, pf = 0.707 lagging
Hence, cos(φ) = 0.707 and sin(φ) = 0.707

The no-load current of a transformer is purely reactive, i.e., it has no real power component. Therefore, the power factor of the no-load current is zero.

Hence, the phase of the no-load current with respect to voltage is purely reactive and lags the voltage by an angle θ or φ.
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A transformer has a primary winding of 800 turns and a secondary winding of 200 turns. When the load current on the secondary is 80A at 0.8 power factor lagging, the primary current is 25A at 0.707 power factor lagging. Determine graphically or otherwise the no-load current of the transformer and its phase with respect to the voltage.?
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A transformer has a primary winding of 800 turns and a secondary winding of 200 turns. When the load current on the secondary is 80A at 0.8 power factor lagging, the primary current is 25A at 0.707 power factor lagging. Determine graphically or otherwise the no-load current of the transformer and its phase with respect to the voltage.? for Railways 2024 is part of Railways preparation. The Question and answers have been prepared according to the Railways exam syllabus. Information about A transformer has a primary winding of 800 turns and a secondary winding of 200 turns. When the load current on the secondary is 80A at 0.8 power factor lagging, the primary current is 25A at 0.707 power factor lagging. Determine graphically or otherwise the no-load current of the transformer and its phase with respect to the voltage.? covers all topics & solutions for Railways 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A transformer has a primary winding of 800 turns and a secondary winding of 200 turns. When the load current on the secondary is 80A at 0.8 power factor lagging, the primary current is 25A at 0.707 power factor lagging. Determine graphically or otherwise the no-load current of the transformer and its phase with respect to the voltage.?.
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