Operation 
  8.2 Faults 
1FT7 synchronous motors 
Operating Instructions, 04/2010, 610.40075.40b 
45 
Table 8- 2  Key to causes of faults and remedial measures 
No.  Cause of fault  How to remedy 
A  Overload  Reduce load 
B  Interruption of a phase in the supply 
cable/motor winding 
Check the frequency converter and supply cables/measure the winding 
resistances and insulation resistances, repair after consultation with 
manufacturer 
C  Interruption of a phase in the supply cable 
after switching on 
Check the frequency converter and supply cables/check the winding 
resistances 
D  Converter output voltage too high, 
frequency too low 
Check the settings on the frequency converter, perform automatic motor 
identification 
F  Winding short circuit or phase short circuit 
in stator winding 
Measure the winding resistances and insulation resistances, repair after 
consultation with manufacturer 
Cooling water not connected/switched off  Check cooling water connection/switch on cooling water G 
Water connection/pipes defective  Locate leaks and seal as necessary, or consult the manufacturer 
Cooling water flow rate too low  Increase cooling water flow rate H 
Inlet temperature too high  Set correct inlet temperature 
Heat dissipation impeded by deposits  Clean the surface of the drives and ensure that the cooling air can flow 
in and out unimpeded 
Cooling air inlet and/or outlet is blocked 
by foreign bodies 
Remove the blockage and ensure that the cooling air can flow in and 
out unimpeded 
I 
Fan motor does not start up  Make sure that the fan motor works properly 
J  Insufficient shielding for motor and/or 
encoder cable 
Check the shielding and grounding 
K  Drive controller gain too high  Adjust the controller 
Rotating parts are grinding  Determine cause and adjust parts 
Foreign bodies in the motor  Send to manufacturer for repair 
L 
Bearing damage  Send to manufacturer for repair 
M  Rotor not balanced  Decouple rotor and rebalance 
N  Rotor out of true, shaft bent  Consult the manufacturer 
O  Poor alignment  Align motor unit, check coupling 
P  Coupled machine not balanced  Re-balance coupled machine 
Q  Shocks from coupled machine  Check coupled machine 
R  Imbalance originating from gearing  Adjust/repair gearing 
S  Cooling water pipes/water connection 
defective 
Locate leaks and seal as necessary, or consult the manufacturer 
If the fault still cannot be resolved after applying the measures specified above, please 
contact the manufacturer or the Siemens Service Center.