1. The main circuit output is 
grounded or short circuited. 
2. Motor auto tuning is performed 
improperly. 
3. The load is too heavy. 
4. The encoder signal is incorrect. 
5. The UPS running feedback 
signal is abnormal. 
1. Check whether the RUN 
contactor at the controller output 
side is normal. 
2. Check whether the power cable 
jacket is damaged, whether the 
power cable is 
possibly short circuited to ground 
and whether the cable is 
connected reliably. 
3. Check the insulation of motor 
power terminals, and check 
whether the motor winding is 
short-circuited or grounded. 
4. Check whether the shorting 
PMSM stator contactor causes 
controller output short circuit. 
5. Check whether motor 
parameters comply with the 
nameplate. 
6. Perform motor auto-tuning 
again. 
7. Check whether the brake keeps 
released before the fault occurs 
and whether the brake is stuck 
mechanically. 
8. Check whether the balance 
coefficient is correct. 
9. Check whether the encoder 
wirings are correct. For 
asynchronous motor, perform 
SFVC and compare the current 
to judge whether the encoder 
works properly. 
10. Check whether the encoder 
lines per revolution is set 
correctly, whether the encoder 
signal is interfered with, whether 
the encoder cable runs through the 
duct independently, whether the 
cable is too long and whether the 
shielding layer is grounded at one 
end. 
11. Check whether the encoder is 
installed reliably, whether the 
1. The main circuit output is 
grounded or short circuited. 
2. Motor auto tuning is performed 
improperly. 
3. The load is too heavy. 
4. The deceleration rate is too 
short. 
5. The encoder is seriously 
interfered with external noise. 
 
1. The main circuit output is 
grounded or short circuited. 
2. Motor auto tuning is performed 
properly. 
3. The load is too heavy. 
4. The encoder is seriously 
interfered with external noise.