Question

A wattmeter has a current coil of $0.03\Omega$ resistance and a pressure coil of $6000\Omega$, the load takes 20 A at a voltage of 220 V and 0.6 power factor. If the current coil is on the load side then the percentage error will be ___________%

• A. 0.45

Answer 1

The correct option is A 0.45
$\text{Power consumed by load =}220\times 20\times 0.6$

$=2640W$

The wattmeter measures the loss in the current coil for this connection,

$\text{Loss in current coil =}{I}^2{R}_c$
$=(20{)}^2\times 0.03=12W$

$\%error=\frac{12}{2640}\times 100=0.45\%$