7-8
Trips and Fault Finding
590+ Series DC Digital Converter
Using the MMI to Manage Trips
Trip Messages
Most of the alarms have a delay timer so that the Converter only trips if the condition persists
for the whole of the delay period.
If the Converter 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 : 0.1 seconds
MISSING PULSE
A missing pulse from the 6-pulse
armature current waveform. Trips when
the motor loading exceeds 1.5 times the
DISCONTINUOUS parameter value.
Firing plug failure
Connection failure
Alarm time delay : 60 seconds
FIELD OVER I
The motor field current has exceeded
120% of the calibrated value
Regulator failure
Badly tuned control loop (alarm only operates with
field current control mode selected)
Alarm time delay : 15 seconds
HEATSINK TRIP
The Converter heatsink temperature is
too high
The ambient air temperature is too high
Poor ventilation or spacing between Converters
Fan failure, check fuse on power board, wrong
rotation (models above 70A bridge rating)
Blocked ventilation slots
Clogged air filters
Excessive armature current - nominal armature
current on motor nameplate should be checked
against the current calibration for the Converter.
Note:
The stack must be allowed to cool in
order to re-start the Converter.
Alarm time delay : 0.75 seconds
THERMISTOR
The motor temperature is too high
Inadequate ventilation
Blower failure -check for direction, clogged air filters
(models above 70A bridge rating)
Excessive armature current - check nominal armature
current on nameplate against current calibration)
Note:
The motor must be allowed to cool in
order to re-start the Converter.
Alarm time delay : 15 seconds
OVER VOLTS (VA)
Motor armature voltage has exceeded
120% of rated volts
Loose armature connection
Badly adjusted field voltage setting
Badly adjusted field current loop
Badly adjusted field-weakening bemf loop
Badly adjusted speed loop
Alarm time delay : 1.5 seconds