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Transformers are rated in KVA because that is a more accurate way to measure their capacity requirements. KWH is apparent power, while KVA is true power, and the ratio between them is power factor. The power factor is a function of the load, and not the transformer, so a poor power factor would make KWA look less to the transformer while, in fact, the true power, if not met by the transformer, could overload the transformer.
Wiki User
∙ 13y ago
Wiki User
∙ 9y agoBecause a transformer has separate ratings for the voltage and the current. The two, multiplied together, give the VA or kVA rating which is independent of any load that might be applied.
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What is the difference between KVA and KW of a transformer?
Transformer power is given by P=V*I which takes the unit of KVA while that of KW has energy term which is not produced by the transformer.It only steps up or down the voltage.Answer:In a pure D.C. circuit, KW = KVA. However, in any A.C. circuit, there is real power {KW} and apparent power {KVA}, due to the voltage and current being out of phase. Power Factor is the ratio of KW to KVA. Transformers are rated in both KVA and PF. Multiplying the transformer KVA rating times the PF will yield KW.A transformer has separate ratings for maximum voltage and maximum current. Multiply the two together and that is called the VA rating, or kVA for larger transformers. So the transformer rating is independent of the power factor of the load.
Why transformer rating is not given in kw?
Transformer rating is based on the maximum temperature a transformer can run at. This temperature is dictated by the amount of current flowing through the transformer windings. This is why transformers are rated in KVA (voltage * current), not kW - it doesn't matter what the phase relationship is between voltage and current, just the magnitude of the current.
Why transformer is measured in kva?
The rating of the machine (kva or kw) depends upon the power factor, since the load power factor to which the transformer is supplying power is not known, it may be capacitive, inductive, or resistive that is why its rating is in kva not in kw.
Why transformer rating is mentioned in kva rather than kw?
Because its measured in kilo volt amps which is the actual reflection of current flowing through the windings. if kw were used as a rating, then it would have to be stated at some power factor
Which is to consider in sizing generator kva or kw ratins?
the unit of generators power is KVA becoze the kva is the power that contain the active power (KW) and the reactive power mean that the name plate of any generator must contain the rated kva of it (like the transformer P (KW) = P (kva) * cos fi P (KW) = V I cos fi for single phase P (KVA) = V I when cos fi closed to 1 this will increase the useful power that exit from the generator or transformer with my pleasure
Why transformer are rated in kVA instead of KW?
Transformers are rated in VA or kVA. That is because the voltage is limited by the power loss in the magnetic core, and the current is limited by the power loss in the resistance of the windings. The rated voltage times the rated current gives the transformer's rating in kVA.
What is the difference between KVA and KW of a transformer?
Transformer power is given by P=V*I which takes the unit of KVA while that of KW has energy term which is not produced by the transformer.It only steps up or down the voltage.Answer:In a pure D.C. circuit, KW = KVA. However, in any A.C. circuit, there is real power {KW} and apparent power {KVA}, due to the voltage and current being out of phase. Power Factor is the ratio of KW to KVA. Transformers are rated in both KVA and PF. Multiplying the transformer KVA rating times the PF will yield KW.A transformer has separate ratings for maximum voltage and maximum current. Multiply the two together and that is called the VA rating, or kVA for larger transformers. So the transformer rating is independent of the power factor of the load.
How can you convert the kva rating into kw rating?
kva*cos(phase angle)
Why transformer rating is not given in kw?
Transformer rating is based on the maximum temperature a transformer can run at. This temperature is dictated by the amount of current flowing through the transformer windings. This is why transformers are rated in KVA (voltage * current), not kW - it doesn't matter what the phase relationship is between voltage and current, just the magnitude of the current.
Why transformer is measured in kva?
The rating of the machine (kva or kw) depends upon the power factor, since the load power factor to which the transformer is supplying power is not known, it may be capacitive, inductive, or resistive that is why its rating is in kva not in kw.
Why alternators are measured in Kva but not in KW?
Depending upon the connected load ( R, RL, RC or RLC) with a transformer, the power goes ou from a transformer may be of two types: 1. Active Power; measured in kW 2. Reactive Power; measured in kVAR If the rating will be in kW, then kVAR rating would not be accounted but if the rating is in kVA then it is possible for us to calculate the total active and reactive current as well as the powers, at a particular system voltage!
Why transformer rating is mentioned in kva rather than kw?
Because its measured in kilo volt amps which is the actual reflection of current flowing through the windings. if kw were used as a rating, then it would have to be stated at some power factor
Why the rating of a transformer is given in kVA?
The rating of a transformer follows the two magnitudes that affect its operation; Volts and Amperes. The other, more popular parameter (kW) is not used on transformers because it depends on connected load Power Factor.
Why transformer is read in rating KVA but not KW?
Transformers are rated in KVA which is equivelant to "apparent power". Loads, {such as heaters, lamps, etc.} are rated in KW which is equivelant to "real power". Things such as power factor and transformer efficiency account for the diifference between the two values. KW's are what the load requires and KVA's are the values of the input power required in order to serve a given KW load. Unfortunately the utilities charge for KVA not KW. It's not too unlike a glass of beer. The enjoyable part is the beer itself. However, you pay for both the beer and the foam at the top of the glass.
Why transformer rated in kva instead of kw?
KW is multiplication of KVA and power factor. Power factor is load dependent and varies as per the type of load. Hence the rating or capacity is mentioned in KVA not in KW
1 12hp motor takes what kva?
12HP is approximately 10.8 KVA. You would want to use a 15KVA transformer to supply this motor. KW = HP * .75 KVA = KW * 1.2 (These formulas are approximate)
Why generating station capacity mentioned in KW even though alternator rating is in KVA?
In generator station the power which produced is real power the real power to me mentioned in its's factor so it is mentioned as KW or MW. In transformer there is no effect of change the power factor (ie:cos,phi) and the power which transfer do not changes its frequency. so, in Transformer and generator it is mentioned as KVA.
