Electrodynamometer Wattmeter – Construction

Electrodynamometer Wattmeter are often used for the measurement of power consumption. The construction of such instrument similar to the construction of electrodynamometer type ammeter and voltmeter. An electrodynamometer wattmeter have two types of coils. One coil is fixed and another coil is moving. The fixed coil is connected in series to the circuit whose power … Read more

Working Principle of Electrodynamometer Wattmeter

Electrodynamometer Wattmeter consists of two coils, pressure coil (PC) and current coil (CC). Pressure coil is connected across the circuit whose power is to be measured and current coil is connected in series. Thus circuit voltage is impressed across the PC and CC carries the circuit current. For constructional detail please read Electrodynamometer Wattmeter – Construction … Read more

Difference between Electrodynamometer Wattmeter and Low Power Factor Wattmeter

Electrodynamometer wattmeter and Low Power Factor (LPF) wattmeters are mostly similar in construction and operation, except for the following modifications are carried out in the electrodynamometer wattmeter to convert it into a LPF wattmeter: Pressure coil resistance is kept low to increase the torque. Compensating coil is used to compensate the Pressure coil current. Capacitor … Read more

Loading Effect in Voltmeter

Ideally the resistance of a Voltmeter is infinite so that so that voltmeter does not alter circuit current. A low resistance voltmeter may give correct reading when measuring voltage in low resistance circuit but the Voltmeter produces unreliable and erroneous reading when connected in high resistance circuit. This is because, as the resistance of voltmeter … Read more

Why Swamping Resistance in Ammeter?

Swamping Resistance in Ammeter can be well understood if we investigate the Effect of Temperature change in the Reading of an Ammeter. Ammeter is basically moving Coil instrument and flow of current through the coil decides the deflection of Ammeter. Now if there is change in the temperature then correspondingly there will also be a … Read more

Significance of Burden in Potential Transformer

Before going into the impact of Burden on the performance of a Potential transformer, we will discuss about Burden. The Burden of an Instrument Transformer is the rated Volt-Ampere loading which is permissible without errors exceeding the limits for a particular class of Instrument Transformer. Basically, there are two Classes of an Instrument Transformer, one … Read more