Why is power rated in kVA?
The real reason is that all AC sources (transformer or alternators) are rated in VA (or KVA or MVA) is because the power factor of current is decided by the load connected. And since the load power factor is not known (while the transformer is being manufactured), they are rated considering resistive load (PF = 1).
How is alternator kVA rating calculated?
Use the formula: P(KVA) = VA/1000 where P(KVA) is power in KVA, V is voltage and A is current in amperes. For example, if V is 120 volts and A is 10 amperes, P(KVA) = VA/1000 = (120)(10)/1000 = 1.2 KVA.
Why the transformers are rated in kVA and not in kw?
The copper loss depends on the current (ampere) flows through the windings of the transformer while the iron loss depends on the voltage (volts). i.e., the rating of the transformer is in kVA.
Why are transformer and alternator ratings in kVA on ships?
The transformer does not alter the power factor of its output power. Transformers are rated in kVA because the losses occurring in the transformers are independent of power factor. KVA is the unit of apparent power. If the transformer is rated in KW, there may be confusions regarding the type of load being connected.
What is kVA rating?
KVA (Kilovolt-Ampere) is the rating most commonly used to rate a generator’s power output. The higher the KVA rating, the more power the generator produces. For adequate power to your equipment, you’ll need a generator with adequate KVAs.
Why transformer is rated in kVA Quora?
Generally transformer rating is in kVA because “ Copper losses ( I²R) depends on Current which passing through transformer winding while Iron Losses or Core Losses or Insulation Losses depends on Voltage.
Why the alternators are rated at kVA or MVA and also the power factors are mentioned in their nameplates?
The temperature rise or heating of alternator depends upon cumulative effect of copper losses and core losses. As there is no role of power factor upon these losses, the rating of alternator generally given in the order of VA or KVA or MVA. That time electrical power factor of the alternator must be specified too.
What does the kVA rating of a transformer mean?
kilovolt-amperes
The kVA unit represents kilovolt-amperes, or 1,000 volt-amperes. A transformer with a 1.0 kVA rating is the same as a transformer with a 1,000 VA rating and can handle 100 volts at 10 amps of current.
What is kVA in generator rating?
A kVA is 1,000 volt-amps. It’s what you get when you multiply the voltage (the force that moves electrons around a circuit) by the amps (electrical current). Kilovolt-amps measure what’s called the ‘apparent power’ of a generator. That means a 20 kVA three-phase generator has a true power of 16 kW (20 x 0.8 = 16).
How is Transformer kVA rating determined?
Example:
- Primary Voltages or High Voltages (H.V) is 11000 volts.
- Primary Current (current on High Voltage side) is 5.25 amps.
- KVA = (√3. V x I) /1000= (1.732 × 11000 × 5.25)/1000=100 KVA.
How is transformer rating determined?
How to Calculate the Rating of Transformer
- The rating of transformer is given in terms of its kVA, HV/LV voltage and phase rotation (for three phase transformer).
- Suppose the load requirement of a utility to be fed is 85 kW, then the kVA rating of transformer should be (85/0.85 = 100).
What is power rating of transformer?
Power transformer ratings are mainly measured in kilovolt amperes (kVA) or megavolt amperes. It means the primary winding and the secondary winding are designed to withstand the kVA or MVA ratings, which is stamped on the transformer nameplate.
Why are alternators and transformers rated in kVA instead of kW?
This is the reason why the motor loads (including synchronous motors are rated in kw) are rated in wattage power. In the case of alternator and transformers manufacturer does not know the operating power factor. Hence they are rated in KVA or MVA
Does the alternator rating depend on power factor?
The alternator conductors are calculated for a definite current and are designed for a definite voltage independent of p.f. (Cos φ) of the load. For this reason apparent power measured in kVA is regarded as the rated power of the alternator. Thus the alternator does not depend on power factor.
How do you calculate the power of a 100kva alternator?
A 100kVA generator or alternator would provide exact 100kW acording to the following formula. If we put the value of Cos θ as 1, The real power (kW) would be equal to the appearnt power (kVA) In case of inductive or capacitive load, suppose the power factor is 0.80. kW = 100 X 0.80 kW= 80 kW.
What is the difference between an alternator and a motor?
For this reason apparent power measured in kVA is regarded as the rated power of the alternator. Thus the alternator does not depend on power factor. whereas a motor is a device that converts electrical to mechanical energy.