Delta MH300 Series - Page 798

Chapter 14 Fault CodesMH300
14-71
ID No. Display Fault Name Description
79
U-phase short circuit
(Aoc)
U-phase short circuit detected when output wiring
detection is performed before the drive runs.
Action and Reset
Action condition 300% of the rated current
Action time Immediately act
Fault treatment parameter N/A
Reset method Manual reset
Reset condition Reset in 5 sec. after the fault is cleared.
Record Yes
Cause Corrective Actions
Incorrect motor wiring
Check if the motor’s internal wiring and the UVW wiring of the drive
output
terminal are correct.
Short-circuit at motor output
due to poor insulation wiring.
Without considering the short circuits, check the motor cable or replace
the cable before turning on the power.
Check for possible burnout or
aging insulation of the motor.
Check the motor insulation value with megger. Replace th
e motor if the
insulation is poor.
Malfunction caused by
interference
Verify the wiring of the control circuit and wiring/grounding
of the main
circuit to prevent interference.
The length of motor cable is
too
long.
Increase the AC motor drive’s capacity.
Install AC reactor(s) on the output side (U/V/W).
Hardware failure
The Aoc
occurs due to short circuit or ground fault at the output side of
the drive.
Check for possible short circuits between terminals with the
electric
meter:
B1 corresponds to U, V, W; DC- corresponds to U, V, W;
corresponds
to U, V, W.
If short circuits occur, return to the factory for repair.