6-11
Possible Causes What to Check and Suggested Measures
(2) Ground faults occurred
at the inverter output
terminals.
Remove the wires connected to the inverter output terminals (U, V,
and W) and perform a Megger test.
Î Remove the part that short-circuited (including replacement o
the wires, relay terminals and motor).
Measure the motor current with a measuring device, and to trace
the current trend. Therefore, use this information to judge if the
trend is over the calculated load value for your system design.
ÎIf the load is too heavy, decrease it or raise the inverter capacity.
(3) Loads were too heavy.
Trace the current trend and check if there are any sudden changes
in the current.
Î If there are any sudden changes, make the load variation smalle
or raise the inverter capacity.
Î Enable instantaneous overcurrent limiting (H12 = 1).
(4) The value set for torque
boost (F09) was too
large. (F37, A13 = 0, 1,
3, or 4)
Check that the output current decreases and the motor does not
come to stall if you set a lower value than the current one for F09
and A05.
Î Lower the value for torque boost (F09 and A05.) if the motor is
not going to stall.
(5) The acceleration/
deceleration time was
too short.
Check that the motor generates enough torque required during
acceleration/deceleration. That torque is calculated from the
moment of inertia for the load and the acceleration/deceleration
time.
Î Increase the acceleration/deceleration time (F07, F08, E10, E11,
and H56).
Î Enable current limiter (F43) and torque limiter (F40 and F41)
Î Raise the inverter capacity.
(6) Malfunction caused by
noise
Check if noise control measures are appropriate (e.g., correct
grounding and routing of control and main circuit wires).
Î Implement noise control measures. For details, refer to
"Appendix A" of the FRENIC-Multi User's Manual.
Î Enable the Auto-reset (H04).
Î Connect a surge absorber to the coil or solenoid of the magnetic
contactor causing the noise.
[ 2 ]
n Overvoltage
Problem The DC link bus voltage was over the detection level of overvoltage.
W
Overvoltage occurs during the acceleration.
W
Overvoltage occurs during the deceleration.
W
Overvoltage occurs during running at constant speed.
Possible Causes What to Check and Suggested Measures
(1) The power supply
voltage was over the
range of the inverter's
specifications.
Measure the input voltage.
Î Decrease the voltage to within that of the specifications.
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