EP Equipment CQD16, Service Manual

Page: 61 / 251

47
REV. 07/2016
DRIVE SYSTEM
5
5
Fault
Motor temperature too high,
controller failure
Cause
a. Stator winding short circuit;
b. Motor U, V and W terminals with
surface ;
c. Bearing failure, resulting in
severe heating;
d. Motor cooling duct blockage
with foreign body;
e. Overload.
6
Fault
On load, motor speed is turning
slow
Cause
a. Insuf fi cient voltage of battery;
b. Overload;
c. U, V, W terminals with abnormal
voltage input;
d. Speed encoder or its circuit
failure.
5.3.3 Checking and Testing
U, V, W Terminals
- Identify if the motor windings are normal
through measuring the resistance of U-V, V-W,
and U-W respectively, if there is short circuit
or breakage;
as shown in the following table:
Due to the small size of windings, when measu-
ring with a multimeter, put it on a low resistance
range.
CAUTION
Resistance
Measurement
Judgment
With readings,
but very low
Normal *
0 Ω
Winding internal short circuit
(replace the motor)
∞ Ω
Winding internal open circuit
(replace the motor)
* The difference between the resistance values
measured at U-V, V-W and U-W shall not be
greater than 2%.
- Identify if there is leakage current through
measuring the resistance between U, V, W
and motor housing respectively.
as shown in the following table:
Resistance
Measurement
Judgment
0 Ω
Leakage current
(replace the motor)
∞ Ω Normal *
* For normal motor, U, V and W terminals are
insulated from motor housing.
Temperature Sensor
Temperature sensor is used to monitor motor
temperature.
Measure the resistance between pin connector
(41#) and (42#) with a multimeter to identify if
the temperature sensor is normal.
As shown in the following table:
Resistance
Measurement
Judgment
With readings Normal
0 Ω
Sensor short circuit
(replace the motor)
∞ Ω
Sensor open circuit
(replace the motor)