Answer / satyanarayana

transforer losses are depends only voltage and curent .so
t/fs rating will be in VA or KVA. in rotating m/cs losses
depends on angle b/w voltage and current.so its rating in
kw or hp

Answer / t

Transformer is a device which transform the power from its
primery to its secondary provided that the frequency and
power remains same (In ideal case the power will be same).
In transformer there is no changing of power factor so its
rating is described in VA.
But the motor is a device that converts the Electrical power
into Mechanical power. In motor applications we concerns
both with with electrical power as well as Mechanical power.
Kw is Electrical term and HP is usually used in Mechanical.
Hence this is the reason as per my knowledge.

Answer / sachin

In trafo losses depend on V , A so rating in VA/KVA/MVA
While in motors losses are frction , rotor , stator cu
losses, etc and these losses are calculated in watts so
rating in HP/ KW

Answer / saravanan.p

Transformer is a static device(no moving parts). The voltage transmission is through mutual inductance(M=L.dI/dt). So losses in transformers are meaning less.So the Power in transformers are mentioned in VA or KVA or MVA.

But in motors are having moving parts. so the inductive coil(Rotor or field)have lagging power factor. The phase difference between voltage and current is called power factor.

The losses in motors are very high compared with transformers. So in motor, the power is noted as KW.

(Note: 1HP=746 Watt or 0.746 KW)


ersaravananp@gmail.com

Answer / vijay yadav

open ckt. chracteristics of tranformer depends upon the open
ckt. voltage while the short ckt chracteristics depnds upon
the short ckt. current.Therefore to combined the effect of
both the chracteristics tranformerrating is done in KVA.

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