Answer / jjj

There are 2 losses in transformer. One is copper loss which depends on current and the other is iron loss which depends on voltage. These two factors are not affected by the power factor. This is why transformers are rated in KVA and not KW. Single phase KVA = Amps x Volts/1000. Single phase KW = Amps x Volts x pf/1000. 3 phase KVA = Amps x Volts x 1.73/1000. 3 phase KW = Amps x Volts x 1.73 x pf/1000.

Answer / tarun aggarwal ymca

We know that Transformer rating may be expressed in kVA as well as Generator and Alternator rated in kVA
There are two type of losses in a transformer;
1. Copper Losses
2. Iron Losses or Core Losses or Insulation Losses
Copper losses ( I²R)depends on Current which passing through transformer winding while Iron Losses or Core Losses or Insulation Losses depends on Voltage.
So the Cu Losses depend on the rating current of the load so the load type will determine the powerfactor P.F , Thats why the rating of Transformer in kVA,Not in kW.
Designer doesn’t know the actual consumer power factor while manufacturing transformers and generators i.e. the P.F (Power factor) of Transformer and Generator/Alternator depends on the nature of connected load such as resistive load, capacitive load, and inductive load as Motors, etc.
But Motor has fixed Power factor, i.e. motor has defined power factor and the rating has been mentioned in KW on Motor nameplate data table. That’s why we are rated Motor in kW or HP (kilowatts/ Horsepower) instead of kVA.
In addition, Motor is a device which converts Electrical power into Mechanical power. In this case, the load is not electrical, but mechanical (Motor’s Output) and we take into the account only active power which has to be converted into mechanical load. Moreover, the motor power factor does not depend on the load and it works on any P.F because of its design.

Answer / altaf chhimpa

Any device is rated depending on losses of the machine. In a transformer the losses are iron losses which depends on voltage and copper losses which depends on current so there are no losses which depend on power factor hence transformer is rated in KVA.

Answer / sagar sahu

1.The transformer losses of depends upon iron and copper losses depends
voltage and current .
2. The load which connected on the transformer is in terms of k/w, iron and copper losses depends voltage and current so the transformer rating in KVA.

Answer / sagar sahu

The transformer is losses is two types
1. copper loss
2. iron loss
The voltage while the copper loss upon the current

The load which connected on the transformer is an terms k/w

Iron loss and copper loss depends upon the voltage and current so the transformer rating is an KVA.

Answer / higiro peter gakwavu

Transformer losses, are copper, iron losses but some times
comes in leakeges. Which some times are negligable.
And mostly, copper losses take alarge portion due to
transformer windings.
kW is for loads, whose losses are normally known to be
caused by heat or I2R, so due to location and the task to be
serviced by atransformer, the power is whole, Apparent
power. As it should meet both inductive, capacitive, and
even resistive equipments in the system.

Answer / dawa

since in case of transformer there is two type of losses i.e
iron and copper loses and they depends on the voltage n
current respectively and its independent of power factor so
transformer r always rated as kva and not in watt and kw

Answer / sarath

yes,it is in KVA due to some constant losses

Answer / gokulkrish

both cu loss and iron loss are indepentent to power factor

Answer / priya

because the copper loss can be expressed only in terms of
voltage and ampere

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