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 leectrodynamometer coil so as to avoid heating. To limit the current through this coil, a resistor is connected in series with the moving coil.
The specification for the meter should specify the reading error for different situations. A limited amount of electric current flows through the moving coil so as to avoid heating. Following are the advantages of electrodynamometer type wattmeters and they are written as follows: Electrical meters Electricity meters Electronic test equipment.
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 linked with the circuit. Therefore the current flowing through the PC is in phase with the circuit voltage V and given as.
Wattmeter – Wikipedia
The two circuits of a wattmeter can be damaged by excessive current. Following are the errors in the electrodynamometer type wattmeters: And the voltage coil is connected in parallel with the circuit.
Posted on June 1, July 24, Author Mr. Following are the advantages of electrodynamometer type wattmeters and they are written as follows:. In order to derive these expressions let us consider the circuit diagram electrodjnamometer below:.
For AC powercurrent and voltage may not be in phase, owing to the delaying effects of circuit inductance or capacitance. Hence moving coil is connected across the voltage and thus the current flowing through this coil is always proportional to the voltage.
But we know that. Before we study the internal construction of electrodynamometer ellectrodynamometerit very essential to know the principle of working of electrodynamometer type wattmeter. The fixed coil is divided into two equal parts and these are connected in series with the load, therefore the load current will flow electrodynamomter these coils. In order to derive these expressions let us consider the circuit diagram given below:. So the expression for the torque can be written as:.
The construction of such instrument similar to the construction of electrodynamometer type ammeter and voltmeter. This particularly affects low power e. Fixed coil is chosen as a current coil as it can be made more massive. The fixed coil is connected in series to the circuit whose power consumption is to be calculated. For the control of movement spring is used. It consists of following parts. Thus, a circuit with a low power factor will give a low reading on the wattmeter, even when both of its circuits are loaded to the maximum safety limit.
This may not be specified in the meter’s manual. So the expression for the torque can be written as: Fixed Coil The fixed coil is divided into two equal parts and these are connected in electroydnamometer with the load, therefore the load current will flow through these coils. Gravity control 2 Spring control, only spring controlled systems are used in these types of wattmeter. Eldctrodynamometer in circuit were power is quite high, Current Transformer shall be used for the measurement of power.
Circuit Globe All about Electrical and Electronics. Their working depends on the theory electrodynamometdr the current carrying conductor placed in a magnetic field experiences a mechanical force.
Thus we see that, angular deflection of electrodynamometer is proportional to the active power being measured. Therefore they can easily carry heavier current.
Let I 1 and I 2 be the instantaneous values of currents in pressure and current coils respectively. The voltage limit of moving coil is limited to about V by the power requirement of voltage circuit since most of the power is dissipated in the series resistor of voltage circuit.
The traditional analog wattmeter is an electrodynamic instrument. The wattmeter is eletcrodynamometer instrument for measuring the electric power or the supply rate of electrical energy in watts of any given circuit.
Moving coil is called Pressure Coil or simply PC. Watmteter wattmeters are used for measurement of utility frequency and audio frequency power; other types are required for radio frequency measurements.
Controlling torque is provided by spring.
In case of electrodynamometer wattmeter, i 1 is current qattmeter PC and i 2 is current through CC. The fixed coil is divided into two equal parts and these are connected in series with the load, therefore the load current will flow through these coils. Fixed coil or CC watmeter carries the circuit current. There are two types of coils present in the electrodynamometer. Both moving coil and fixed coils are air cored. Let the rms voltage of circuit is V and current flowing is I.