Page 127 - CITS - Electrician - Trade Practical
P. 127
ELECTRICIAN - CITS
Test value of IR of electrical machines
Name of the machine/ Recommended Recorded
Sl. No Remarks
Equipment IR value (MΩ) Value (MΩ)
Induction motor
1 > 2 MΩ 100 MΩ Very good IR
3 Ph. 415 V
Transformer
2 > 2 MΩ 150 MΩ Very good IR
3 Ph. 400/230 V
AC Generator
3 > 2 MΩ 120 MΩ Very good IR
3 Ph. 415 V
Armored UG cable
4 > 2 MΩ 100 MΩ Very good IR
4 core, 25 mm
2
Ballast
5 > 2 MΩ 0 Short circuit
230 V AC
Universal motor
6 > 2 MΩ 1 MΩ Poor
230 V AC
Safety precautions:
1 While operating megger do not touch its terminals which gives electric shock.
2 Handle the megger properly and avoid mechanical damage.
3 Ensure to switch OFF the main supply while checking insulation resistance of power cables.
4 Do not use the megger for checking continuity of coils of motors, relays etc
110
CITS : Power - Electrician & Wireman - Exercise 53
