## Power Factor Meter

Thepower factor of a circuit can be found out from the wattmeter reading and voltmeter and ammeter readings suitably connected in the circuit.   Power factor = Wattmeter reading / (Voltmeter reading x ammeter reading).   Power factor = True Power / Apparent Power   This method involves mathematical calculations. Sometimes it is required to …

## Earth Tester Working Principle

Hi friends,   In this article, I am going to describe the earth tester working principle and method of earth resistance measurement by it. I hope you will find it informative and helpful.   The Resistance of the earth can be measured with the help of megger earth tester or earth megger. Earth Tester Working …

## Working Principle of Megger

The Megger insulation tester is an instrument used for measuring high resistances of the order of mega-ohms and for testing the insulation resistance. The instrument generates its EMF when the cranking handle is turned. It has two terminals marked ‘Line’ and ‘Earth’. The crank is turned at a moderate speed till a constant deflection of …

## Working Principle of Multimeter & Construction

A multimeter is the most commonly used instrument by technicians and engineers in the laboratory, as well as other repair works. As it is clear from the name of this instrument, it can make many (multi) measurements with reasonable accuracies such as AC and DC voltages, currents, and resistances. In this article, I am discussing …

## Dynamometer Type Wattmeter Working

A dynamometer type wattmeter is basically a moving coil instrument. But in this case, the operating field is produced by the fixed coil instead of a permanent magnet. A wattmeter in which fixed coils produce the operating field is known as a dynamometer type wattmeter.   The dynamometer type wattmeters are very significant because we …

## Range Extension of Ammeters and Voltmeters

There is no fundamental difference in the operating principles of ammeters and voltmeters. Both are current operated devices (except electrostatic type voltmeters) i.e. deflecting torque is produced when current flows through their operating coils. In an ammeter, the deflecting torque is produced by the current to be measured or by a definite fraction of it whereas …

## Moving Coil Instrument Working Principle

Hi friends, in this article, I am going to discuss about moving coil instrument working principle and other related information. You will appreciate my effort, I hope so.   The simple view of construction of moving coil instrument is shown in the figure. It consists of a powerful permanent shoe magnet. A light rectangular coil …

## Moving Iron Instrument

The moving iron instruments or MI instruments are quite cheap in cost, simple in construction and very accurate at fixed power supply frequency. These instruments can be used on AC as well as DC. Therefore, these are widely used in laboratories and on switching panels. These instruments are used either as ammeters or voltmeters only. …

## Deflecting | Controlling | Damping Torque

In order to ensure proper operation of indicating instruments, the following three torques are required: Deflecting torque. Controlling torque. Damping torque. What is deflecting torque?   One important requirement in indicating instruments is the arrangement for producing operating or deflecting torque (Td) when the instrument is connected in the circuit to measure the given electrical …

## No Load Test of Induction Motor

The no load test and the blocked rotor test are two main induction motor tests, which are performed on induction motor to know the different losses, power factor and efficiency of the induction motor.   No Load Test of Induction Motor     The no load test of 3 phase induction motor is performed on …