Calculating Kw
Calculating Kw
(OP)
I'm an electrical engineer in the US and need to clarify a dispute with a co-worker. We are working on a project in Russia where voltage and hertz are different from the US. We are sizing Generator Sets and have to calculate kVA to kW @ 50Hz.
What is the formula for converting kVA to kW for 50Hz? I know it is not he same as 60Hz (kVA * pf). I say kW is higher than kVA at 50Hz and kW is lower or equal to kVA at 60Hz depending on Power Factor (pf). Any feedback would be appreciated.
Thank You,
Nitro
What is the formula for converting kVA to kW for 50Hz? I know it is not he same as 60Hz (kVA * pf). I say kW is higher than kVA at 50Hz and kW is lower or equal to kVA at 60Hz depending on Power Factor (pf). Any feedback would be appreciated.
Thank You,
Nitro





RE: Calculating Kw
Sorry to say but you will have to buy the drink for your co-worker. The laws of electrical engineering do not change just because the fundamental frequency is different. KW is always equal to KVA times power factor. This can get more detailed if we start talking about displacement power factor versus true power factor so for arguments sake just assume no harmonics exist.
;)
RE: Calculating Kw
KVA = sqrt(KW^2 + KVAR^2)
If you play around with this in a spreadsheet, you will see that KW can never exceed KVA. The best you can get is KW=KVA and that occurs when the power factor is 100%.
RE: Calculating Kw
Nitro
RE: Calculating Kw
Blacksmith
RE: Calculating Kw
RE: Calculating Kw
RE: Calculating Kw
However, at any particular frequency the relationships between the kW and kVA are calculated identically. Just the numbers going in (current and power factor, assuming V is same for both) will be different for a particular motor depending on whrther you try to energise it at 50 or 60Hz.
So, you are both right and shold buy each other a drink
Bung
Life is non-linear...
RE: Calculating Kw