# A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The

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A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The proportion of full load at maximum efficiency is

A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The proportion of full load at maximum efficiency is 0.707

## Related questions

At full -load of a transformer, the iron loss and copper loss are 3000 W and 4000 W respectively. Then total loss at maximum efficiency is :  (A) 7000 W (B) 6000 W (C) 8000 W (D) 4000 W

A transformer operates 24 hours day at full -load. It's full -load efficiency is :  (A) equal all day efficiency (B) more than all -day efficiency (C) less than all -day efficiency (D) equal to maximum efficiency

A ferrite core has less eddy current loss than an iron core because?

The eddy current loss in a dc generator is 400 W at 40 Hz frequency of reversal and constant flux density. When frequency is increased to 50 Hz., eddy current loss is :  (A) 256 W (B) 320 W (C) 500 W (D) 625 W

A 500 kVA, 3-phase transformer has iron losses of 300 W and full load copper losses of 600 W. The percentage load at which the transformer is expected to have maximum efficiency is  (A) 50.0% (B) 70.7% (C) 141.4% (D) 200.0%

The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be :  (A) 34.64 kVA (B) 75 kVA (C) 20 kVA (D) None of the above

Define kVA rating of transformer.

The core construction is like spokes of a wheel in following transformer:  (A) Berry Type Transformer (B) Core Type Transformer (C) Shell Type Transformer (D) None of the above

The main purpose of using core in a transformer is to (A) decrease iron losses (B) eliminate magnetic hysteresis (C) reduce reluctance of the common magnetic circuit (D) prevent eddy current loss

The size of a transformer core will depend on?

Why does the core of a transformer need to be laminated?

Reduction in core losses and increase in permeability are obtained with transformer employing?

Why Transformer rating is given in kVA?

When secondary of a current transformer is open-circuited its iron core will be?

The desirable properties of transformer core material are  (1) low permeability and low hysteresis loss. (2) high permeability and high hysteresis loss. (3) high permeability and low hysteresis loss. (4) low permeability and hysteresis loss.

A transformer has maximum efficiency at 3/4 full load. The ratio of its iron losses and full load copper loss is : -  a) 16/9 b) 4 / 3 c) 3/4 d) 9 /16

A transformer has negative voltage regulation when its load power factor is   (1) Zero (2) Unity (3) Leading (4) Lagging

One 200 KVA transformer has an iron loss of 1 KW and full load Cu loss of 2 KW. Its load KVA corresponding to maximum efficiency is:  (A) 100 KVA (B) 141.4 KVA (C) 50 KVA (D) 200 KVA

In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of?

In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are?

The maximum load that a power transformer can carry is limited by its?

A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are (A) 140 W (B) 180 W (C) 240 W (D) 480 W

For a transformer, operating at constant load current, maximum efficiency will occur at?

Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is?

The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is?

Full load copper loss in a transformer is 1600 watts. At half load the copper loss will be: A) 6400 watt B) 1600 watt C) 800 watt D) 400 watt

A 400/200 volts transformer has pu impedance of 0.05. The HV side voltage required to circulate full load current during short circuit test is

A single-phase transformer has no-load loss of 64 W, as obtained from an open circuit test. When a short-circuit test is performed on it with 90% of the rated currents flowing in its both LV and HV windings, he measured loss is 81 W. The transformer has maximum efficiency when operated at  (A) 50.0% of the rated current (B) 64.0% of the rated current (C) 80.0% of the rated current (D) 88.8% of the rated current

What is difference between KW and KVA?

A single core lead sheathed cable with two dielectrics of permittivity 4 and 3, respectively, are subjected to same maximum stress. If the conductor diameter is 1.5 cm, the outer diameter of the first dielectric is (A) 1.125 cm (B) 1.5 cm (C ) 2 cm (D) 8 cm

A single-phase, 50 kVA, 250 V/500 V two winding transformer has an efficiency of 95% at full load, unity power factor. If it is re-configured as a 500 V/750 V auto-transformer, its efficiency at its new rated load at unity power factor will be  (A) 95.752% (B) 97.851% (C) 98.276% (D) 99.241%

A 4000 kVA, 11 kV/132 kV delta-star connected 3-phase transformer has reactance, x1 = 0.12 p.u. The actual value of x1 referred to the low voltage side is (A) 0.85 Ω (B) 3.63 Ω (C) 36.3 Ω (D) 252 Ω

Compare copper and aluminium.

How do magnets and copper wire make electricity?

A zener voltage regulator has load requirements of 12 V and 2 A. The zener diode minimum current requirement is 0.2 A. The minimum voltage at input is 24 V. What is the required value of series resistance with source? A) 5.45 Ω B) 6 Ω C) 7.2 Ω D) 6.38 Ω