590 Series DC Digital Drive Trips and Fault Finding
7-9
Trip Message and Meaning Possible Reason for Trip
SPEED FEEDBACK
The difference between speed feedback and
armature voltage feedback is greater than the
SPDFBK ALM LEVEL parameter value
The speed feedback and armature voltage feedback
are of opposite polarity and both greater than10%
If FLD WEAK ENABLE parameter is enabled, speed
feedback is less than 10% when in the field
weakening region
Analog tacho feedback polarity incorrect (terminals G3 and G4)
The ENCODER SIGN parameter’s polarity is incorrect
Disconnection of wiring, including fibre optics
Armature voltage calibration has not been suitably reduced when running at
reduced field currents
Tachogenerator failure
Tachogenerator coupling failure
Alarm time delay : 0.125 seconds
ENCODER FAILED
No speed feedback signal
The SPEED FBK SELECT parameter is set to ENCODER but an optional Encoder
board is not fitted
Where applicable, check fibre optic cable for damage, bend radius, operating
length - refer to the Microtach handbook.
Check cable and connections on wire-ended encoder
FIELD FAIL
Field current is less than 6% of rated current when in
Current Control mode
Field current is less than 50mA when in Voltage
Control mode (with field current scaling switches set
to 0.2A)
Open circuit motor field - check connection and measure field resistance
Faulty operation of field controller
Where an ac supply feeds the onboard field regulator, check connections FL1 &
FL2 for line-to-line voltage (rather than line-to-neutral) - L1 into FL1, L2 into FL2.
Note that the 3-phase supply must be present for mains synchronisation purposes.
For loads where no field supply is required, e.g. a permanent magnet motor, set
the FIELD ENABLE parameter to DISABLED to suspend this alarm.
Alarm time delay : 1 second
3-PHASE FAILED
3-phase supply failure
Total failure of supply, or missing phase of 3-phase supply (detected under most
circumstances) - check supply to the controller, check high-speed thyristor stack
protection fuses, check power chassis coding fuses.
Check the mains voltage of the Drive (refer to the Product Code). This alarm may
not operate properly with controller if the voltage is incorrect, i.e. wrong unit or
controller.
PHASE LOCK
Supply frequency is outside the frequency band limits
45 - 65Hz
Check supply frequency
Synchronisation errors caused by distorted supply
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