Transformer is always rated in KVA (Kilo Volt Amps) not KW, why? Because transformer design doesn't depend on power factor. We know that Power can be divided in two fraction viz Active Power and Reactive Power. We also call it as wattfull and wattless components.
Apparent Power square = Active power square + Reactive power square.
Active power is the power which we can use for transformation in to different form of energy/power like mechanical energy. Whereas we can't utilize the reactive power which is only loss. we generate Apparent power and out of that we can utilize the active component only not the reactive component.
Active power = Current.Voltage.(Load power factor); load power factor is the active component i.e Cosine of Angle between Current and voltage.
Whereas
Reactive power = current.voltage.(sine of angle between current and voltage). This component leads to only loss and unit is KVAr.
This power factor depends upon the type of load like inductive or capacitance load, better we can say legging or leading load/power factor.
Our target is always to maintain zero angle between the current and voltage or unity power factor.
So design of Transformer doesn't depend on the power factor, it can be used for variable power factor. Designer mainly concentrate on the Iron loss and copper loss of Transformer. Transformer can be used for both inductive as well as Capacitive Load. So it can be used for any power factor.
That is why Transformer ratings are always given KVA as the Iron loss depends upon Voltage and Copper loss depends on Current, not on power factor which is variable.
So transformer can be used for both type of load Legging as well as Leading. And hence Transformer is effect-less for Power factor.
Apparent Power square = Active power square + Reactive power square.
Active power is the power which we can use for transformation in to different form of energy/power like mechanical energy. Whereas we can't utilize the reactive power which is only loss. we generate Apparent power and out of that we can utilize the active component only not the reactive component.
Active power = Current.Voltage.(Load power factor); load power factor is the active component i.e Cosine of Angle between Current and voltage.
Whereas
Reactive power = current.voltage.(sine of angle between current and voltage). This component leads to only loss and unit is KVAr.
This power factor depends upon the type of load like inductive or capacitance load, better we can say legging or leading load/power factor.
Our target is always to maintain zero angle between the current and voltage or unity power factor.
So design of Transformer doesn't depend on the power factor, it can be used for variable power factor. Designer mainly concentrate on the Iron loss and copper loss of Transformer. Transformer can be used for both inductive as well as Capacitive Load. So it can be used for any power factor.
That is why Transformer ratings are always given KVA as the Iron loss depends upon Voltage and Copper loss depends on Current, not on power factor which is variable.
So transformer can be used for both type of load Legging as well as Leading. And hence Transformer is effect-less for Power factor.
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