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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The pointer is fixed on the moving coil which is placed between the fixed coils.

Now let us derive the expressions for the controlling torque and deflecting torques. Therefore, a wattmeter is rated not only in watts, but also in volts and amperes. Wikimedia Commons has media related electrldynamometer Wattmeters.

Electrodynamometer Type Wattmeter

As discussed earlier in the post, a series resistor is used in PC to limit the current upto mA. Due to this current proportional to supply voltage flows through the moving coil.

From Wikipedia, the free encyclopedia. There are two current coils which are kept at constant position and the measurable current will flow through those current coils. Limited of current flows through the moving coil so as to avoid heating. As simple as other voltmeter and ammeter connection. If a pointer is connected with the moving coil, which will move of a scale, then the deflection can be easily measured by connecting the moving coil with that pointer.

Now let us look at constructional details of Electrodynamometer Type Wattmeter. By using this site, you agree to the Terms of Use and Privacy Policy.

The specification for the meter should specify the reading error for different situations. The moving is air cored and is mounted on a pivoted spindle and can move freely.


Electrodynamometer Wattmeter – Construction | Electrical Concepts

Please keep doing this. 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 wattjeter to the current through current coil hence current through the current coil can be considered as equal to total load current.

There is uniform scale is used in these types of instrument as moving coil moves linearly over a range of 40 degrees to 50 degrees on either sides. Thus we see that, angular deflection of electrodynamometer is proportional to the active power being measured.

The lowest measurable current is given as 0. It uses for measuring the power of both the AC and DC circuits. Assuming the electrical resistance of the pressure coil be very high hence we can neglect reactance with respect to its resistance.

Electrodynamometer Wattmeter

An electrodynamometer wattmeter have two types of coils. So in order to limit the electric current we have connect the high value resistor in series with the moving coil.

Your email address will not be electrodynamimeter. Errors may be due to mutual inductance effects. So the expression for the torque can be written as: Notify me when new comments are added.

Electrodynamometer Type Wattmeter

Therefore for higher voltage Potential Transformer shall be used. 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 electrodynampmeter with the circuit. A current flowing through the current coil generates an electromagnetic field around the coil. They can be used for both to measure AC as well as DC quantities elecrodynamometer scale is calibrated for both.


The torque acts on eectrodynamometer coils becomes. But the instrument will respond to the average deflecting torque over a time period. In fact, a watt meter is a package of an ammeter and a voltmeter, because the product of voltage and current is the power, which is the measurable quantity of a watt meter When current flows through the current coils, then automatically a magnetic field is developed around those coils.

Therefore this fixed coil is often called Current Coil or simply CC. Therefore in circuit were power is quite high, Current Transformer shall be electrodynamkmeter for the measurement of power.

Also, on analog wattmeters, the potential coil carries a needle that moves over a scale to indicate the measurement. Hence moving coil is connected across the voltage and thus the current flowing through this coil is always proportional to the voltage.

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.

Circuit Globe All about Electrical and Electronics. So the expression for the torque can be written as: Errors may be due to pressure coil capacitance.

A voltage coil is placed inside those two current coils, and this voltage coil is totally free to rotate.