Insulation Resistance Measurements On Motors - AEMC 1005 User Manual

4.2.6

Insulation Resistance Measurements on Motors

Figure 8 shows reading the resistance to ground of a three-phase motor
winding. Since the three-phase motors are internally connected, it is only
necessary to connect one lead to the motor lead and the other lead to the
motor frame as shown.
Figure 9 shows the wind-
ings of a three-phase
motor separated.
Sometimes this can be
done at the lead termi-
nals, while other times
the end bells must be
removed to get at the
lead wires of the coils.
By connecting the meg-
ohmmeter as shown, the
phase insulation resis-
tance value can now be
determined.
Read between phases "A"
and "B", then "B" and "C",
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then "C" and "A".
14
Figure 8
A
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6
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MΩ - 500 V
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MΩ - 1000 V
1000 Ω
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10 Ω −
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MODEL 1015
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C
B
Figure 9
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MΩ - 1000 V
1000 Ω
10 Ω +
10 Ω −
MEGOHMMETER
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MODEL 1015
I N S T R U M E N T S
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