Explain the term reactive power. Why it is sometimes essential to measure reactive power?

Explain the term reactive power. Why it is sometimes essential to measure reactive power?
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Answer :

Reactive power: The reactive power (Q) is defined as the product of voltage(V), current (I) and sine of angle between voltage(V) and current( I) Therefore Reactive power Q = V I sinΦ The reactive power is also called as imaginary power and its unit is VAR or kVAR. Reactive power is part of total power which is not consumed by the load. Reactive power simply travels from source to load and back. It is therefore useless power and hence should be minimized.

Need to measure reactive power: Increase in reactive power causes the reduction in power factor. There are several disadvantages of poor power factor. The supply utility system has decided to pay incentive or charge penalties if power factor of consumer increases or decreases beyond certain limit. Therefore it is essential to measure the reactive power so that corrective measures can be taken accordingly to maintain systems power factor near to the unity.

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