Electrical Instruments

hotwire instrument1

Hotwire instrument

Hotwire instrument is one of the types of electrothermal instrument, another one is thermocouple instrument. Both the hotwire instrument and thermocouple instrument use the heating effect of current flowing through resistance to cause meter deflection. Since the operation of both of the instruments depends only on the heating effect of current flow, they may be …

Hotwire instrument Read More »

AC potentiometer

The potentiometer is an instrument that is used for the measurement of potential differences across a known resistance between two terminals of a circuit. Potentiometers are of two types DC potentiometer and AC potentiometer. The working principle of both the potentiometer is the same except for one difference that is discussed later in this article. …

AC potentiometer Read More »

current transformer

Current transformer

In the power system, the level of current and voltage is very very high and that’s why it is not possible to measure it with conventional instruments without damaging anything. For such cases, an instrument transformer is used to step down the voltage and the current within the range of the existing measuring instruments. Instrument …

Current transformer Read More »

Electrodynamometer

Electrodynamometer instrument: Construction, Working principle, and more

Electrodynamometer instruments are very similar to PMMC instruments except that the permanent magnet is replaced by the coil. These instruments can be used for both AC and DC Electrodynamometer instruments are used as a voltmeter, ammeter, wattmeter, power factor meter, and frequency meter with some modification. But most commonly these instruments have been used as …

Electrodynamometer instrument: Construction, Working principle, and more Read More »

Permanent magnet moving coil

The permanent magnet moving coil instruments (PMMC)

The permanent magnet moving coil instrument or in short PMMC instruments. These PMMC instruments are very accurate and useful in DC measurements. The permanent magnet moving coil instruments are also known as D’alvanometer. Construction of PMMC instruments The permanent magnet moving coil instruments consist of several parts. These parts are explained below : Permanent magnets …

The permanent magnet moving coil instruments (PMMC) Read More »

Moving iron instruments

Moving iron instrument

Moving iron instruments or MI instruments are widely used in labs and switchboards. Most commonly these MI instruments are used in ammeter and voltmeter. Working principle of MI instrument: The working principle of moving iron instruments is when several soft iron pieces are caused to move by the magnetic field of a fixed coil excited …

Moving iron instrument Read More »