14
Megohmmeter Model 1015
4.2.4
Tips For Successful Insulation Resistance Testing
• Check with the equipment manufacturer for factory insulation
resistance readings.
• Do not rely on insulation resistance testing alone as proof of winding
conditions.
• Do not expect the same value for all parts of all machines.
• Observe consistent test time duration, recognizing that total current
through insulation under test will vary with time.
• Correct all readings properly to a standard reference temperature
(see IEEE Std. #43-1974, Temperature Correction Curve).
• Know what you are testing. Isolate the piece of equipment from other
circuitry.
• Watch trends rather than relying on single “spot” readings.
4.2.5 Insulation Measurement - Connections
Figure 3 shows the connections to measure the insulation of one conduc-
tor to the other conductors. The cable should be disconnected at both
ends to avoid leakage through switchboards and panels.
Figure 3
OFF
M
Ω
- 1000 V
M
Ω
- 500 V
1000
Ω
AEMC
I N S T R U M E N T S
MEGOHMMETER
M O D E L 1 0 1 5
Battery
Check
10
Ω +
10
Ω −
0.1
0.5
1
5 10
50 100
500
1000
0
1
2
3
4
5
6
7
8
9
10
0
100
200
300
400
500
600V
600V
-
+
6
!
M
Ω
Cable Insulation
Conductor Under Test
+
-
