0
Unit or say Rating of transformer is in KVA and not in KW because copper loss of a transformer depends on current and iron loss on voltage. Hence, Total transformer loss depends on volt-ampere ( VA ) and not on phase angle between voltage and current i.e. it is independent of load power factor. That is why Unit or say Rating Of Transformer Is In KVA and not in KW.
Still curious? Ask our experts.
Chat with our AI personalities
Judy
Vivi
FranThe transformer has two types of losses :
a. copper loss
b. core loss
As we know Copper loss is totally depends on the current of the transformer and the core losses depends on voltage of the transformer.
This can u also find in " No load test and On load test".
So the rating of transformer is in VA.
Dhiraj Shringi
Alternative AnswerA transformer's iron losses depend on the magnitude of the flux which, in turn, is proportional to voltage, while its copper losses depend on the winding currents. As both iron and copper losses contribute to the maximum operating temperature of the transformer, it follows that a transformer must be rated in terms of voltage and current. In alternating current systems, the product of voltage and current is apparent power, expressed in volt amperes.
As a transformer's secondary voltage is kept approximately constant, it is its 'volt ampere' rating that determines its maximum (secondary) load current.
Expressing a transformer's rating in watts (i.e. true power) would be completely meaningless because, with a highly-reactive load, it will be supplying practically zero watts while still possibly having to supply its rated current.
it indicates the power handling capacity of the transformer
AnswerA transformer's iron losses depend on the magnitude of the flux which, in turn, is proportional to voltage, while its copper losses depend on the winding currents. As both iron and copper losses contribute to the maximum operating temperature of the transformer, it follows that a transformer must be rated in terms of voltage and current. In alternating current systems, the product of voltage and current is apparent power, expressed in volt amperes.As a transformer's secondary voltage is kept approximately constant, it is its 'volt ampere' rating that determines its maximum (secondary) load current.
Expressing a transformer's rating in watts (i.e. true power) would be completely meaningless because, with a highly-reactive load, it will be supplying practically zero watts while still possibly having to supply its rated current.
Well, smaller Transformers are rated in VA, bigger ones in KVA, huge ones in MVA. The amps (A in KVA) are what matter the most. They generate heat and copper losses in the transformer. The manufacturer has no way to know what the power factor of the load will be, so cannot easily put a KW rating on the transformer. Suppose the transformer is rated 100 KVA. If it is supplying a kiln with a resistive heating element, it can deliver 100 KW to the load. But if the transformer is feeding a computer data center, with many (reactive) computer power supplies, resulting in a low power factor, it will be able to deliver only a fraction of 100 KW. The problem is the reactive current still flows in the transformer windings, still causes heating and losses, but does not contribute real power to the load. It is up to the electrical system designer to characterize the anticipated load, determine what the power factor will most likely be, and size the transformer accordingly.
Because commonly we say : some hardware (e.g. transformer, speaker etc.) has XX Watts which corresponds to Real(Active) power (usually the only one measured by old traditional counters) but we have also Apparent power and Reactive Power (that occurs when we have current lagging to voltage (which is not measured by traditional spinning magnetic core counters) . KVA (kilo volt-ampere) is used to measure the capacity (or power) of power transformer because it's more exact in terms of expressing power.
AnswerA transformer's iron losses depend on the magnitude of the flux which, in turn, is proportional to voltage, while its copper losses depend on the winding currents. As both iron and copper losses contribute to the maximum operating temperature of the transformer, it follows that a transformer must be rated in terms of voltage and current. In alternating current systems, the product of voltage and current is apparent power, expressed in volt amperes.
As a transformer's secondary voltage is kept approximately constant, it is its 'volt ampere' rating that determines its maximum (secondary) load current.
Expressing a transformer's rating in watts (i.e. true power) would be completely meaningless because, with a highly-reactive load, it will be supplying practically zero watts while still possibly having to supply its rated current.
Add your answer:
Earn +20 pts
Why you are indicating capacity of transformer in KVA?
transformer action doesn't depend on power factor that is why we indicate its rating in KVA
What is kva rating of single phase transformer?
This is the rated output of the transformer, obtained by multiplying the rated secondary voltage by the rated secondary current. And it's 'kV.A', not 'kva'.
What is a full load current in single phase transformer?
It is the rated maximum current that can be taken from the transformer. This is equal to the VA rating divided by the output voltage. So a 6 kVA 240 v transformer would have a maximum current rating of 6000/240 or 25 amps.
How the ka rating of mccb is calculated?
ka of mccb=transformer(KVA)x100/1.732xsecondary voltagex%impedence of transformer
480 transformer to 120 ac current what is the kva on transfomer?
The kVA rating will be listed on the transformer's nameplate, which is usually on the front of the transformer. The 480v to 120v is irrelevant, because many transformers with different kVA ratings convert 480 volts to 120 volts. The kVA ratings can be different and thus affect the rated current through the transformer.
