| |
Insulation Resistance Readings |
|
|
| Table 45 Normal
Ohm and Megohm Values Between All Leads and Ground |
| Condition of Motor and Leads |
Ohm Value |
Megohm Value |
|
A new motor (without drop cable).
A used motor which can be reinstalled in well.
|
200,000,000 (or more)
10,000,000 (or more)
|
200.0 (or more)
10.0 (or more)
|
| Motor in well. Readings
are for drop cable plus motor. |
2,000,000 (or more)
500,000 - 2,000,000
Less than 500,000
|
2.0 (or more)
.50 - 2.0
Less than .5
|
|
New motor.
Motor in good condition.
Insulation damage, locate and repair.
|
|
|
Insulation resistance varies very little with rating. Motors
of all HP, voltage, and phase rating have similar values of
insulation resistance.
Table 45 is based
on readings taken with a megohm meter with a 500VDC output.
Readings may vary using a lower voltage ohmmeter. Consult
Franklin Electric if readings are in question.
|
|
Resistance of Drop Cable (Ohms) |
|
| The values
below are for copper conductors. If aluminum conductor drop
cable is used, the resistance will be higher. To determine the
actual resistance of the aluminum drop cable, divide the ohm
readings from this chart by .61. This chart shows total resistance
of cable from control to motor and back
Winding Resistance Measuring
The winding resistance measured at the motor should fall within
the values in Tables 13,
22, 24
& 26. When
measured through the drop cable, the resistance of the drop
cable must be subtracted from the ohmmeter readings to get
the winding resistance of the motor. See table below.
|
| |
DC Resistance
in Ohms per 100ft. of Wire (Two conductors) @ 50°F
| AWG or MCM Wire Size (Copper) |
14 |
12 |
10 |
8 |
6 |
4 |
3 |
2 |
| Ohms |
.544 |
.338 |
.214 |
.135 |
.082 |
.052 |
.041 |
.032 |
|
|
| 1 |
1/0 |
2/0 |
3/0 |
4/0 |
250 MCM |
300 MCM |
350 MCM |
400 MCM |
500 MCM |
600 MCM |
700 MCM |
| .026 |
.021 |
.017 |
.013 |
.010 |
.0088 |
.0073 |
.0063 |
.0056 |
.0044 |
.0037 |
.0032 |
|
|
| |
| |
|
|
Page 44
