Draw and explain the circuit diagram for measurement of single phase power using dynamometer type wattmeter.

Draw and explain the circuit diagram for measurement of single phase power using dynamometer type wattmeter. 
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1 Answer

Answer :

Circuit diagram for measurement of single phase power using dynamometer type wattmeter:

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Explanation: It consists of two stationary coils, called current coils and one moving coil, called voltage or potential coil. The moving coil is mounted on the spindle, in the gap between two stationary coils, as shown. The current coils are connected such that they carry the current proportional to (or equal to) the load current and the voltage coil is connected in such a way that it carries the current proportional to the load voltage. The interaction between two magnetic fields causes the production of force on moving system, which is proportional to the product of voltage and current i.e. power. The meter can be calibrated directly to indicate the power in watts. 

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