It consists of following parts There are two types of coils present In electrodynamometer type wattmeter, moving coil works as pressure coil. • Hence moving. Electrodynamometer Type Wattmeter Construction and Working Principle Advantages of Electrodynamometer Type Wattmeter Error in. Before we study the internal construction of electrodynamometer type wattmeter, it is essential to know the working principle of.


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So the expression for the torque can be written as: Where, x is the angle.

Now let the applied value of voltage across the pressure coil be Assuming the electrical resistance to the pressure coil be very high hence we can neglect reactance with electrodynamometer type wattmeter to its resistance.

In this the impedance is equal to its electrical resistance therefore it is purely resistive. If there is phase difference between voltage and electric current, then expression for instantaneous current through current coil can be written as As current through the pressure coil is very very small compared to the current through current electrodynamometer type wattmeter hence current through the current coil can be considered as equal to total load current.

Hence the instantaneous value of torque can be written as Average value of deflecting torque can be obtained by integrating the instantaneous torque from limit 0 to T, where T is the time period of the cycle.

Dynamometer Type Wattmeter Working Principle | Electrodynamometer | Electrical Academia

Now let us derive the expressions for the controlling torque and deflecting torques. In order to derive these expressions let us consider the circuit diagram given below: Electrodynamometer Type Wattmeter Electrodynamometer type wattmeter know that instantaneous torque in electrodynamic type instruments is directly proportional to product of instantaneous values of currents flowing through both the coils and the rate of change of flux linked with the circuit.

Let I1 and I2 be the instantaneous values of electrodynamometer type wattmeter in pressure and electric current coils respectively. So the expression for the torque can be written as: Padeepz Comment 0 Electrodynamometer Type Wattmeter Electrodynamometer Type Wattmeter in general, a watt meter is used to measure the electric power of a circuit, or sometime it also measures the rate of energy transferred from one circuit to another circuit.

Electrodynamometer Type Wattmeter

When a moving coil that is free to rotate is kept under the influence of a current carrying conductor, then automatically a mechanical force will be applied to the moving coil, and this force will make a little deflection of the moving coil. If a pointer is connected with the moving coil, which will move of a electrodynamometer type wattmeter, then the deflection can be electrodynamometer type wattmeter measured by connecting the moving coil with that pointer.


This type of watt meter electrodynamometer type wattmeter of two types of coil, more specifically current coil and voltage coil. There are two current coils which are kept at constant position and the measurable current will flow through those current coils.

  • Electrodynamometer Type Wattmeter
  • Electrodynamometer Type Wattmeter Construction and Working Principle

A voltage coil is placed inside those two current coils, and this voltage coil is totally free to rotate. Electrodynamometer type wattmeter current coils are arranged such a way, that they are connected with the circuit in series.

Consequently, current Iv through the moving coil is directly proportional to the load voltage.

The scale electrodynamometer type wattmeter the wattmeter is illustrated in figure 2 in which upper scale is calibrated in milli-watts while the lower one measures the power in watts range.

Wattmeter Scale Because fairly large currents are required to set up the necessary field flux, the dynamometer instrument is not as sensitive as a PMMC instrument. Because of the inductance, the current of the pressure coils electrodynamometer type wattmeter behind the voltage.


Thus, the power factor of the wattmeter becomes lagging, and the meter reads high reading. Pressure Coil Capacitance — The pressure coil has capacitances along with the electrodynamometer type wattmeter. This capacitance increases the power factor of the instrument.

Electrodynamometer Type Wattmeter | Electrical Study App by SARU TECH

Hence causes the error in the reading. Eddy Current Error — The eddy current induces in the coil creates its own magnetic field.


This field affects the main current flows through the coil. Thus, the error occurs in the reading. Thus, affect their reading.

Temperature Error — The variation in temperature will change the resistance of the pressure coil.