Toros
Senior Member
- Location
- Tujunga, CA
Hi,
What is the difference between KVA and Kw or VA and W
What is the difference between KVA and Kw or VA and W
KVA = Apparent PowerHi,
What is the difference between KVA and Kw or VA and W
KVA is the maximum power that a power system can supply and KW is the actual power it supplies to the load connected.
By stating KVA as the maximum power that a power system is able to supply, and KW is the actual power supplied to the load, the necessity of introducing power factor into the explanation is avoided. The power factor concept may be introduced later after the OP has understood the first concept.VA is simply volts X amps.
It would be confusing to the OP when he encounters such equipment, if he leaves this thread with the understanding of KVA and KW but without understanding the power factor, the connecting link between the two.Which will be confusing if the questioner encounters a generator or fuel cell or other power plant for which the kW limit is the actual power that can be delivered, because of the limitations of the energy source rather than the current source.
And the kVA figure can only be delivered because not all of it represents real power.
Another is because we have to consider both iron losses (related to voltage) and copper losses (related to current) and our equipment has to be able to handle thermal loading from both.
I understand that an unloaded transformer has losses due to the impedance of the primary and due to heating the iron core. But are there additional iron losses as the transformed due to secondary loading?
Just trying to understand.
Thanks
To put it simply, the iron losses are related to the voltage (eddy currents, etc.) and the copper losses are related to the load current. Transformers are thermally loaded just from being energized even if there is no load attached to the secondary (iron losses). The secondary load adds additional thermal load (copper losses).I understand that an unloaded transformer has losses due to the impedance of the primary and due to heating the iron core. But are there additional iron losses as the transformed due to secondary loading?
Just trying to understand.
Thanks
And that connecting link is a very important part that was left out of what you said in post #2, OP asked what the difference was, your answer was not wrong, but came short of explaining the difference.It would be confusing to the OP when he encounters such equipment, if he leaves this thread with the understanding of KVA and KW but without understanding the power factor, the connecting link between the two.
OK. I have a 3-phase 110kW, 400V motor. The efficiency is 93%.By stating KVA as the maximum power that a power system is able to supply, and KW is the actual power supplied to the load, the necessity of introducing power factor into the explanation is avoided.
Hi,
What is the difference between KVA and Kw or VA and W
Yes, transformer losses are proportional to the load.
FWIW, your statement is only strictly true for constant voltage (flat line ) DC. For pulsed
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