Question

full elaborate explanation of the advantages and disadvantages of induction type instruments

Answer 1

Introduction:

The measuring instruments or indicating instruments are classified according to their working principle. Generally there are four types of instruments, which are according to the type of effect used in it. they are as follows,

1) magnetic effect

2) Induction effect

3) Electrothermic effect

4) Electrostatic effect

working principle of Induction type instrument:

The working principle of induction type instrument is similar to the induction motor principle. when a current carrying conductor is placed in rotating magnetic field an eddy current is induced in it. the reaction between the rotating magnetic field and eddy current will create a torque for deflection to measure the electrical quantity voltage, current or energy. the eddy current is directly proportional to torque. this induction type meter can be further classified into split phase type instrument and shaded pole type instrument

Advantages:

1) Compared to other type of instruments the damping more effective

2) The effects due to stray magnetic field is less, since the strength of operating magnetic field is high.

3) High torque to weight ratio

4) most of the energy meters are of induction type only

Disadvantages:

1) since these kind of instrument work on induction principle, this instrument can be used to measure only AC quantity and DC cannot be measured

2) Since power consumption is more, the continuous monitoring is not recommended.

3) change in temperature and frequency may cause error in measurement, so proper compensation must be used

4) scale is not uniform