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Answer:
Transformers are rated in kVA (kilo-volt-amperes) instead of kW (kilowatts) because kVA accounts for both real power (kW) and reactive power, which is essential for sizing and designing electrical systems.
Reasoning:
Transformers are devices used to transfer electrical energy between circuits. They handle both real power (expressed in kilowatts, kW) and reactive power (expressed in kilovolt-amperes, kVA). Reactive power is necessary for maintaining voltage levels and supporting inductive loads in electrical systems. Therefore, transformer ratings are specified in kVA to consider both real and reactive power components accurately.
FAQs:
Q: Why isn’t the transformer rated in kW like other electrical equipment?
A: Transformers handle both real power (kW) and reactive power, so their rating is specified in kVA to account for both components.
Q: What is the difference between kW and kVA in transformer ratings?
A: kW represents real power, while kVA includes both real power and reactive power.
Q: Why is reactive power important in transformers?
A: Reactive power is essential for maintaining voltage levels and supporting inductive loads in electrical systems.
Q: Can a transformer operate without reactive power?
A: No, transformers require reactive power to function correctly and maintain voltage stability.
Q: How does the load type affect the kVA rating of a transformer?
A: Inductive loads require more reactive power, influencing the transformer’s kVA rating.
Q: Does a higher kVA rating mean higher energy consumption?
A: No, the kVA rating reflects the capacity of the transformer to handle both real and reactive power, not its energy consumption.
Q: What happens if a transformer is underrated in kVA for a specific application?
A: Underrated transformers may experience voltage drops or overloads, leading to inefficient operation and potential damage.
Q: Can a transformer be overloaded in terms of kVA?
A: Yes, exceeding the transformer’s kVA rating can lead to overheating and failure.
Q: How do transformers contribute to power factor correction?
A: Transformers with proper kVA ratings help improve power factor by supplying reactive power to inductive loads.
Q: Are there international standards for specifying transformer ratings in kVA?
A: Yes, various international standards such as IEC and ANSI provide guidelines for transformer rating specifications.