How does power measured in wattmeter attained in relation to Electrodynamometer movement?

Working Principle of Electrodynamometer When electrodynamometer wattmeter is connected in the circuit to measure the electric power. The current coil carries the load current and the potential coil carries a current proportional to the load voltage.

How is torque produced in wattmeter?

The current and voltage of the fixed and moving coil respectively produce the two magnetic fields. The interaction of these two magnetic fields deflects the pointer of the instrument. The deflection of the pointer is directly proportional to the power flows through it.

What is the function of Electrodynamometer?

Electrodynamometer-type instruments are very useful for accurate measurement of RMS values of voltages irrespective of waveforms. Because of precision grade accuracy and the same calibration for ac and dc measurements, these instruments are useful as transfer type and calibration instruments.

How Electrodynamometer can be used for power measurement?

The Electrodynamometer wattmeter has two coils i.e., fixed and moving coils. The fixed coil is connected in series with the circuit in order to measure power consumption. The supply voltage is applied to the moving coil.

Where is the power dissipated in the Electrodynamometer?

Both moving coil and fixed coils are air cored. The voltage limit of moving coil is limited to about 600 V by the power requirement of voltage circuit since most of the power is dissipated in the series resistor of voltage circuit.

What type of damping torque is used in wattmeter?

Air friction damping is used, as eddy current damping will distort the weak operating magnetic field and thus it may leads to error. There is uniform scale which is used in these types of instrument as moving coil moves linearly over a range of 40 degrees to 50 degrees on either side.

When measuring power with an Electrodynamometer wattmeter in a circuit have a low power factor?

when measuring power with the electrodynamometer wattmeter in a circuit having a low power factor : the current coil should be connected on the load side. the current coil should be connected on the supply side. the pressure coil should be connected on the load side.

What type of control is used for Electrodynamometer type wattmeter?

The gravity control and the spring control are the two types of control system. Out of two, the Electrodynamometer Wattmeter uses spring control system. The spring control system is used for the movement of the pointer.

What are the advantages of Electrodynamometer?


  • Electrodynamometer instruments can be used for both AC and DC and voltage.
  • No sign of eddy current error and hysteresis error.
  • These instruments are very useful for accurate measurements of the RMS value of voltage irrespective of the waveform.
  • Dynamometer are precision grade instruments.

What is the limitation of Electrodynamometer type wattmeter?

(i) They have a low torque/weight ratio and hence have a low sensitivity. (ii) Low torque/weight ratio gives increased frictional losses. (iii) They are more expensive than either the PMMC or the moving iron type instruments.

How is deflecting torque calculated?

The controlling torque is directly proportional to the angle of deflection of the coil. Control torque Ct =Cθ where, θ = deflection angle in radians and C = spring constant Nm /rad .

What is MLC in wattmeter?

The terminal M & L represents Current coil While C & V Potential coil. The M terminal connects to the power supply. ‘L’ it is used to connect load. ‘C’ it is shorted with M. ‘V’ it is a voltage to connect transformer neutral and also.