Pressure coil of wattmeter is to calculate voltage of line, so connected across line in parallel.
Higher resistance give more accurate voltage reading, So, we connect many resistor in series so that resultant resistance across line should be high and no(very less) current should pass through it and all current should force to pass through current coil, this will lead accurate reading of current too.

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We connect more resistance in series to make the total resistance is high so that it wont absorb any power (amperes) for the circuit so i wont affect on the true reading and also the series coil to measure the current has very small resistance not to affect the total resistance not to affect on the total current
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soomnath paul
Answered On : Feb 2nd, 2013
High resistance is connected in order to make the voltage appeared across the pressure coil in phase with the applied one.
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