Electrical and Instrumentation Engineering: Unit IV: Measurements and Instrumentation

Principles of Operation of Electrical Instruments

An electrical instrument essentially consists of a movable element and a scale to indicate or register the electrical quantity being measured. The movable element is supported on jewelled

PRINCIPLES OF OPERATION OF ELECTRICAL INSTRUMENTS

An electrical instrument essentially consists of a movable element and a scale to indicate or register the electrical quantity being measured. The movable element is supported on jewelled

Bearings and carries a pointer or sets of dials. The movement of the movable element is caused by utilizing one or more of the following effects of current or voltage:

1. Magnetic effect-Moving-iron instruments

2. Electrodynamics' effect- (i) Permanent-magnet moving coil (ii) Dynamometer type

3. Electromagnetic-induction-Induction type instruments

4. Thermal effect- Hot-wire instruments

5. Chemical effect-Electrolytic instruments

6. Electrostatic effect-Electrostatic instruments

Table 4.1. The principles of operation of electrical instruments are given in the table for facility of reference.


Electrical and Instrumentation Engineering: Unit IV: Measurements and Instrumentation : Tag: : - Principles of Operation of Electrical Instruments