Electrodynamometer Wattmeter consists of two coils, pressure coil (PC) and current coil (CC). Pressure coil is connected across the circuit. ELECTRODYNAMOMETER. WATTMETER’S. • These instruments are similar in design and construction to electrodynamometer type ammeters and voltmeters. Before we study the internal construction of electrodynamometer wattmeter, it very essential to know the principle of working of electrodynamometer type.

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Limited of current flows through the moving coil so as to avoid heating.

Please keep doing this. This site uses Akismet ellectrodynamometer reduce spam. So the expression for the torque can be written as: Dynamometer type wattmeter works on very simple principle and this principle can be wattmrter as “when any electric current carrying conductor is placed inside a magnetic fieldit experiences a mechanical force and due this mechanical force deflection of conductor takes place”.

The current and voltage of the fixed and moving coil generate the two magnetic fields.

Electronic wattmeters are used for direct, small power measurements or electrodynmometer power measurements at frequencies beyond the range of electrodynamometer-type instruments.

The moving is air cored and is mounted on a pivoted spindle and can moves freely. Gravity controlled system cannot be employed because they will appreciable amount of errors.

Electrodynamometer Type Wattmeter

Both moving coil and fixed coils are air cored. In this way, the deflection of the pointer will proportional to both current and voltage of the circuit. Notify me when new comments are added. The fixed coil is connected in series to the circuit whose power consumption is to be calculated. Please help improve this article by adding citations to reliable sources.

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. 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.


For AC powercurrent and voltage may not be in phase, owing to the delaying effects of circuit inductance or capacitance. Moving coil moves the pointer with the help of spring control instrument. Leave a Reply Cancel reply Your email address will not be published. The device consists of a pair of fixed coilsknown as current coilsand a movable coil known as the potential coil.

Air friction damping is used. Connects Facebook Youtube Videos. The deflection of the pointer is directly proportional to the power flows through it. Now the reason is very obvious of using two fixed coils instead of one, so that it can be constructed to carry considerable amount of electric current.

Wattmeter – Wikipedia

Air friction damping is used, as eddy current damping will distort the weak operating magnetic field and thus it may leads to error. There are two types of coils present in the electrodynamometer. Thermistors and thermocouples are used to measure heat produced by RF power and can be calibrated either directly or by comparison with a known reference source of power.

The lowest measurable current is given as 0. The readings may be displayed on the device, retained to provide a log and calculate averages, or electrodhnamometer to other equipment for further use. We know that instantaneous torque in electrodynamic type instruments is directly proportional to the product of instantaneous values of currents flowing through both watfmeter coils and the rate of change of flux linked with the circuit.

The two pressure coils can be connected in series or parallel to change the ranges of the wattmeter.


They can be used for both to measure AC as well as DC quantities as scale is calibrated for both. Let the rms voltage of circuit is V and current flowing is I.

Before we study the internal construction of electrodynamometer wattmeterit very essential to know the principle of working of electrodynamometer type wattmeter. This is because the position of the pointer depends on the power factorvoltage and current.

But we know that. An electrodynamometer wattmeter have two types of eattmeter.

Electrodynamometer Wattmeter

Leave a Reply Cancel reply Your email address will not be published. Gravity control 2 Spring control, only spring controlled systems are used in these types of wattmeter. Instruments with moving coils can be calibrated for direct current or power frequency currents up to a few hundred hertz. Control System Out of two controlling systems i. A dynamo meter type watt meter is used in various applications where the power or energy transfer has to be measured.

Therefore we need to calculate the average of deflecting torque T d. Working Principle of Electrodynamometer Wattmeter. If the pressure coil is purely resistive, then their current is in phase with the voltage.

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Electrodynamometer Type Wattmeter | Electrical Study App by SARU TECH

The average deflection torque is obtained by integrating the torque from 0 to T limit. Gravity controlled system cannot be employed because they will appreciable amount of wattmetef. Therefore, a wattmeter is rated not only in watts, but also in volts and amperes. Views Read Edit View history. One coil is fixed and another coil is moving.

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