| Insulation Resistance |
- Open master breaker and disconnect all leads from control
box or pressure switch (QD type control, remove lid) to
avoid electric shock hazard and damage to the meter.
- Set the scale lever to R X 100K and set the ohmmeter
on zero.
- Connect one ohmmeter lead to any one of the motor leads
and the other lead to the metal drop pipe. If the drop pipe
is plastic, connect the ohmmeter lead to ground.
|
- If the ohms value is normal (Table
45 ), the motor is not grounded and the cable
insulation is not damaged.
- If the ohms value is below normal, either the windings
are grounded or the cable insulation is damaged. Check the
cable at the well seal as the insulation is sometimes damaged
by being pinched.
|
| Winding Resistance |
- Open master breaker and disconnect all leads from control
box or pressure switch (QD type control, remove lid) to
avoid electric shock hazard and damage to the meter.
- Set the scale lever to R X 1 for values under 10 ohms.
For values over 10 ohms, set the scale lever to R X 10.
"Zero" the ohmmeter.
- On 3-wire motors measure the resistance of yellow to
black (Main winding) and yellow to red (Start winding).
On 2-wire motors measure the resistance from line to
line.
Three-phase motors measure the resistance line to line
for all three combination.
|
- If all ohms values are normal (Tables 13,
22, 24
& 26), the motor
windings are neither shorted nor open, and the cable colors
are correct
- If any one value is less than normal, the motor is shorted.
- If any one ohm value is greater than normal, the winding
or the cable is open, or there is a poor cable joint or
connection.
- If some ohms values are greater than normal and some
less on single-phase motors, the leads are mixed. See Page
44 to verify cable colors.
|
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