In a single-phase transformer, the total iron loss is 2500 W at nominal voltage of 440V and frequency 50 Hz. The total iron loss is 850 W at 220 V and 25 Hz. Then, at nominal voltage and frequency, the hysteresis loss and eddy current loss respectively are

A single-phase, 4 kVA, 200 V/100 V, 50 ~Hz transformer with laminated CRGO steel core has rated no-load loss of 450 W. When the high-voltage winding is excited with 160 V, 40 Hz sinusoidal AC supply, the no-load losses are found to be 320 W. When the high-voltage winding of the same transformer is supplied from a 100 V, 25 Hz sinusoidal AC source, the no-load losses will be …………… W (rounded off to 2 decimal places).

A single-phase transformer of rating 25 kVA, supplies a 12 kW load at power factor of 0.6 lagging. The additional load at unity power factor in kW (round off to two decimal places) that may be added before this transformer exceeds its rated kVA is __________.

A 3-phase 900kVA, , 50Hz transformer has primary (high voltage side) resistance per phase of and secondary (low voltage side) resistance per phase of . Iron loss of the transformer is 10kW. The full load % efficiency of the transformer operated at unity power factor is ______ (up to 2 decimal places).

A single-phase 400V, 50Hz transformer has an iron loss of 5000W at the rated condition. When operated at 200V, 25Hz, the iron loss is 2000W. When operated at 416V, 52Hz, the value of the hysteresis loss divided by the eddy current loss is _______.

For a single phase, two windings transformer, the supply frequency and voltage are both increased by 10%. The percentage changes in the hysteresis loss and eddy current loss, respectively, are        

A single-phase transformer has no-load loss of 64W, 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, the measured loss is 81W. The transformer has maximum efficiency when operated at  

A single-phase 50kVA, 250V/500V two winding transformer has an efficiency of 95% at full load, unity power factor. If it is reconfigured as a 500V/750V autotransformer, its efficiency at its new rated load at unity power factor will be

A 300 kVA transformer has 95% efficiency at full load 0.8 pf lagging and 96% efficiency at half load, unity pf.

The iron loss  and copper loss  in kW, under full load operation are

A 300 kVA transformer has 95% efficiency at full load 0.8 pf lagging and 96% efficiency at half load, unity pf.

What is the maximum efficiency (in %) at unity pf load?

A 500 kVA, 3-phase transformer has iron loses of 300 W and full load copper losses of 600 W. The percentage load at which the transformer is expected to have maximum efficiency

A single phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is

The hysteresis loop of a magnetic material has an area of 5 with the scales given as 1 cm = 2AT and 1 cm = 50mWb.  At 50 Hz, the total hysteresis loss is

The percentage resistance and percentage reactance of a 10kVA, 400V/200V, 3-phase transformer are 2% and 10% respectively. If the constant losses in the machine are 1%, the maximum possible percentage efficiency of the transformer is:

The efficiency of a 100KVA transformer is 0.98 at full as well as at half load. For this transformer at full load the copper loss

A 50Hz transformer having equal hysteresis and eddy current losses at rated excitation is operated at 45Hz at 90% of its rated voltage. Compared to rated operating point, the core losses under this condition:

In a 50 KVA, 11 KV/400V transformers, the iron and copper losses are 500W and 600W respectively under rated conditions. Calculate the efficiency on unity power factor at full load. Find the load for maximum efficiency and the iron and copper losses corresponding to this load.

The hysteresis and eddy current losses of a single phase transformer working on 200V, 50 Hz supply are  respectively. The percentage decrease in these, when operated on a 160V, 40 Hz supply are :