Fuji Electric FRENIC-HVAC User Manual page 639

[ 1 ] OCn Instantaneous overcurrent
Problem The inverter momentary output current exceeded the overcurrent level.
OC1 Overcurrent occurred during acceleration.
OC2 Overcurrent occurred during deceleration.
OC3
Overcurrent occurred during running at a constant speed.
Possible Causes
(1) The inverter output lines
were short-circuited.
(2) Ground faults have occurred
at the inverter output lines.
(3) Overload.
(4) Excessive torque boost
specified.
(when F37 = 0, 1, 3, or 4)
(5) The acceleration/
deceleration time was too
short.
(6) Malfunction caused by noise.
[ 2 ] EF Earth fault
Problem An earth fault current flowed from the output terminal of the inverter.
Possible Causes
(1) An earth fault occurred at the
inverter output terminal(s).
9.3 If an Alarm Code Appears on the Monitor
What to Check and Suggested Measures
Disconnect the wiring from the inverter output terminals ([U], [V] and
[W]) and measure the interphase resistance of the motor wiring. Check if
the resistance is too low.
 Remove the short-circuited part (including replacement of the wires,
relay terminals and motor).
Disconnect the wiring from the output terminals ([U], [V] and [W]) and
perform a Megger test.
 Remove the grounded parts (including replacement of the wires,
relay terminals and motor).
Measure the motor current with a measuring device to trace the current
trend. Then, use this data to judge if the trend is over the calculated load
value for your system design.
If the load is too heavy, reduce it or increase the inverter capacity.
Trace the current trend and check if there are any sudden changes in the
current.
 If there are any sudden changes, make the load fluctuation smaller or
increase the inverter capacity.
Enable instantaneous overcurrent limiting (H12 = 1).

Check whether decreasing the torque boost (F09) decreases the output
current but does not stall the motor.
 If no stall occurs, decrease the torque boost (F09).
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.
 Increase the acceleration/deceleration time (F07, F08, E10 through
E15, and H56).
 Enable the current limiter (F43) and torque limiter (F40, F41, E16,
and E17).
 Increase the inverter capacity.
Check if noise control measures are appropriate (e.g., correct grounding
and routing of control and main circuit wires).
 Implement noise control measures. For details, refer to Appendix A.
 Enable the Auto-reset (H04).
 Connect a surge absorber to magnetic contactor's coils or other
solenoids (if any) causing noise.
What to Check and Suggested Measures
Disconnect the wiring from the output terminals ([U], [V], and [W])
and perform a Megger test.
 Remove the earthed parts (including replacement of the wires,
relay terminals and motor).
9-5