Fuji Electric FRENIC MEGA G2 Series - Page 641

6.3 If an Alarm Code Appears on the LED Monitor
6-27
TROUBLESHOOOTING
Chap 6
[ 39 ] 0Un Overvoltage
Phenomenon: The DC intermediate circuit voltage was over the detection level of overvoltage.
0U1 Overvoltage occurred during acceleration.
0U2 Overvoltage occurred during deceleration.
0U3 Overvoltage occurred during running at constant speed.
Possible cause
Check and measures
(1) The power supply voltage
exceeded the inverter's mode
range.
Measure the input voltage.
➔ Decrease the voltage to within the specified range.
➔ If the power supply voltage is within the specification range, the
inverter may be faulty. Contact your Fuji Electric representative.
(2) A surge current entered the
input power supply.
In the same power line, if a phase-advancing capacitor is turned
ON/OFF or a thyristor converter is activated, a surge (momentary large
increase in the voltage or current) may be caused in the input power.
➔ Install a DC reactor.
(3) The deceleration time was too
short for the moment of inertia
of the load.
Recalculate the deceleration torque based on the moment of inertia of
the load and the deceleration time.
➔ Increase the deceleration time (F08, E11, E13, E15, and H56).
➔ Enable the anti-regenerative control (H69), or deceleration
characteristics (H71).
➔ Set torque limit (F40, F41, E16, E17) to become effective.
➔ Set the rated voltage at base frequency (F05*) to “0” to improve the
braking capability.
➔ Consider the use of a braking resistor.
(4) The acceleration time was too
short.
Check if the overvoltage alarm occurs after rapid acceleration.
➔ Increase the acceleration time (F07, E10, E12, and E14).
➔ Select the Curve acceleration/ deceleration (H07).
➔ Consider the use of a braking resistor.
(5) Braking load is too heavy.
Compare the braking torque of the load with that of the inverter.
➔ Set the rated voltage at base frequency (F05*) to “0” to improve the
braking capability.
➔ Consider the use of a braking resistor.
(6) A ground fault occurred at the
output side.
If the motor runs normally with the wiring disconnected from the inverter
output terminals (U, V, W).
➔ Check whether a ground fault has occurred at the output wiring or
motor.
If overvoltage is displayed when the inverter is run with the wiring
disconnected from the inverter output terminals (U, V, and W).
➔ The inverter may be faulty. Contact your Fuji Electric representative.
(7) Malfunction caused by noise.
Check if the DC intermediate circuit voltage was below the protective
level when the overvoltage alarm occurred.
➔ Take noise countermeasures. For details, refer to Appendix A.
➔ Enable the retry function (H04).
➔ Connect a surge absorber to magnetic contactor's coils or other
solenoids (if any) causing noise.
 The explanations for function codes with an asterisk (*) are limited to motor 1. If using motor 2 to 4, replace
with the relevant function codes in Chapter 5 "Table 5.3-21 Function codes to be switched".
[ 40 ] Pbf Charge circuit fault (FRN0008G2S-2G/FRN0004G2□-4G or above)
Phenomenon: The magnetic contactor for short-circuiting the charging resistor failed to work.
Possible cause
Check and measures
(1) The charging circuit is faulty.
Inverter repair is necessary.
➔ Contact your Fuji Electric representative.