and can moves freely. • In electrodynamometer type wattmeter, moving coil works as pressure coil. • Hence moving coil is connected across the voltage and thus. Study of ammeter, voltmeter and wattmeter connections. • To investigate the errors .. an electrodynamometer for use as a wattmeter is shown in Fig. is kep. 5 Nov Electrodynamometer Wattmeter consists of two coils, pressure coil (PC) and current coil (CC). Pressure coil is connected across the circuit.

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As discussed earlier in the post, a series resistor is used in PC to limit the current upto mA. The motor used for this purpose is called a wattmeter, and the instrument that can be applied as a wattmeter is known as a dynamometer, or sometimes as an electrodynamic instrument.

For the control of movement spring is used. This means, of course, that deflection is also proportional to the current through the field coils. The major difference from the PMMC construction is that the permanent magnet is replaced by two coils, as illustrated in figure 1 a.

Electrodynamometer Wattmeter – Construction | Electrical Concepts

Your email address will not be published. Construction and Working Principle Advantages Errors. Submit Your Questions Here! Now let the applied value of voltage across the pressure coil be Assuming the electrical resistance of the pressure coil be very high hence we can neglect reactance with respect to its resistance.

Errors may be due to mutual inductance effects. Errors in Electrodynamometer Type Wattmeter Following are the errors in the electrodynamometer type wattmeters: The average deflection torque of the coil is given as.


This mechanical force deflects the pointer which is mounted on the calibrated scale. Control System Out of two controlling systems i.

Electrodynamometer Type Wattmeter

Therefore this fixed coil is often called Current Coil or simply CC. The deflection of the pointer of a dynamometer instrument is proportional to the current through the moving coil, but it is also proportional to the flux density of the magnetic field set up by the stationary coils. You must be logged in to post a comment.

Errors caused by vibration of moving system. The torque acts on the coils becomes. Therefore we need to calculate the average of deflecting torque T d. Spring Control is used in such instrument for proving controlling torque.

They can be used for both to measure ac as well dc quantities as scale is calibrated for both. We know that instantaneous torque in electrodynamic type instruments is directly proportional to the product of instantaneous values of currents flowing through both the coils and the rate of change of flux linked with the circuit.

It is important to avoid excessive current flow in the voltage and current coils of a wattmeter. These coils are called the current coils of electrodynamometer type wattmeter.

In this the impedance is equal to its electrical resistance therefore it is purely resistive. In case of electrodynamometer wattmeter, i 1 is current through PC and i 2 is current through CC. In earlier design of Electrodynamometer wattmeter the fixed coil were designed to carry current of the order of A.

Have a Referral code? Moving coil is called Pressure Coil or simply PC.

Fixed coil is chosen as a current coil as it can be made more massive. And the value of current is given by the equation.


Hence the current flows through the pressure coil is considered as the total load current. Posted 6 days ago. In a DC Circuit, the power supplied to a load can be determined by measuring the load voltage and current and multiplying them together: Ask electrodynanometer Question Submit Now.

Electrodynamometer Wattmeter

Consequently, current I v through the moving coil is directly proportional to the load voltage. Following are the errors in the electrodynamometer type wattmeters: When set to the 60 V range, the applied voltage should not exceed 60 V even when the pointer indication is less than full scale. Learn how your comment data is processed. Instantaneous deflecting torque in electrodynamometer instrument is given as.

The deflection of the pointer is directly proportional to the power flows through it. 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.

The error caused by inductance of pressure coil is compensated by connecting a capacitor across a part of series resistance in the pressure coil circuit, as shown in fig Low Power Factor Wattmeter Electro-dynamometer Type. Moving coil is connected across the supply voltage. For this we connect wattmfter wattmeter to the circuit as shown in figure below.

An investigation of a proposed investment has been made. Posted 9 days ago. Due to this the sizes of earlier wattmeter were large.

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