Question

Which of the following types of measuring instrument is used only for AC system?
1. Electrodynamic type
2. Attraction type
3. Repulsion type
4. Shaded-pole type

Answer 1

Correct Answer - Option 4 : Shaded-pole type

Induction type shaded pole instruments:

• The operation of induction type instruments depends on the production of torque due to reaction between two magnetic fluxes having some phase difference
• These types of instruments are used only for AC measurements
• Induction type instrument have good damping
• Induction type instruments are less effect of stray magnetic fields as the operating fields are large

 

• Moving coil instruments are used to measure only DC quantities.
• Moving iron instruments (both attraction type and repulsion type) are used to measure both AC and DC quantities.
• Electrodynamic instruments are used to measure both AC and DC quantities.