13
5.4 Insulation resistance
(lead-to-ground)
To check the insulation resistance (lead-to-
ground) of the motor and leads, use a
megohmmeter and follow these steps:
1. Turn the POWER OFF.
2. Disconnect all electrical leads to the motor.
3. Set the scale selector on the megohm-
meter to R x 100K, touch its leads
together, and adjust the indicator to zero.
4. Touch the leads of the megohmmeter
individually to each of the motor leads and
to ground (i.e. L to ground; N to ground,
etc.).
Fig. 9
Insulation resistance measurement
Evaluation
The resistance values for new motors must
exceed 1,000,000 ohms. If they do not,
replace power head.
5.5 Winding resistance (line-to-line)
To check the winding resistance of the motor
windings, use a megohmmeter and follow
these steps.
1. Turn the POWER OFF.
2. Disconnect all electrical leads to the motor.
3. Set the scale selector on the
megohmmeter to R x 1, touch its leads
together and adjust the indicator to zero.
4. Using the charts in section 5.6 for
reference, touch the leads of the
megohmmeter to the appropriate pair of
connectors. Check all pairs that are pres-
ent and write down and label (RA
1
, RS
1
,
RS
2
) all readings.
- In T-box at L & N: UP will = Speed 3/High
- In T-box at L & N: UPS value depends on
the selected speed (Speed 1, 2, or 3)
- For both UP and UPS: with the terminal
box removed, check all combinations RA,
S
1
, S
2
5. Compare your readings to the matching
model, phase and voltage listed in the
charts in section 5.6.
Evaluation
The resistance values must fall within the
tolerances listed in section 5.6. If they do not,
replace the power head.
TM
04
5
638
36
09
