Trips and Fault Finding 7-13
DC590+ Series DC Digital Drive
Using the MMI to Manage Trips
Trip Messages
Most of the alarms have a delay timer so that the Drive only trips if the condition persists for the whole of the delay period.
If the Drive trips, then the display immediately shows a message indicating the reason for the trip. The possible trip messages are given in the table
below.
Trip Message and Meaning Possible Reason for Trip
OVERSPEED
Motor overspeed - the speed feedback signal has
exceeded 125% of rated speed.
Badly adjusted speed loop (alarm only operates with encoder or armature volts
feedback selected)
Alarm time delay : 50 milliseconds
MISSING PULSE
A missing pulse from the 6-pulse armature current
waveform. This trip is only enabled when the motor
loading exceeds 1.5 times the DISCONTINUOUS
parameter value.
Note that the MISSING PULSE trip is not intended or
able to protect the drive if a thyristor fails to function
during regenerative operation. This can result in
damage to the drive.
We recommend fusing the armature circuit if
regenerative operation is intended. The MISSING
PULSE trip is intended to detect firing circuit
connector problems during motoring operation of
the drive.
Firing plug failure
Connection failure
Alarm time delay : 60 seconds
FIELD OVER I
The motor field current has exceeded 120% of the
calibrated value
External field has incorrect supply phases applied
(Alarm only operates with field current control mode selected)
Alarm time delay : 10 seconds
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