Fuji Electric FRENIC-HVAC User Manual page 640

[ 3 ] OVn Overvoltage
Problem The DC link bus voltage was over the detection level of overvoltage.
OV1 Overvoltage occurred during acceleration.
OV2 Overvoltage occurred during deceleration.
OV3 Overvoltage occurred during running at constant speed.
Possible Causes
(1) The power supply voltage
exceeded the inverter's
specification range.
(2) A surge current entered the
input power supply.
(3) The deceleration time was too
short for the moment of inertia
for load.
(4) The acceleration time was too
short.
(5) Braking load was too heavy.
(6) Malfunction caused by noise.
(7) Excessive high-frequency
current from outside
(Occurred during stoppage
after turning ON main power.)
[ 4 ] LV Undervoltage
Problem DC link bus voltage has dropped below the undervoltage detection level.
Possible Causes
(1) A momentary power failure
occurred.
(2) The power to the inverter was
switched back to ON too soon
(when F14 = 1).
What to Check and Suggested Measures
Measure the input voltage.
 Decrease the voltage to within the specified range.
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 an AC reactor.
Recalculate the deceleration torque based on the moment of inertia for
the load and the deceleration time.
 Increase the deceleration time (F08, E11, E13, E15, and H56).
 Enable the automatic deceleration (anti-regenerative control) (H69),
or deceleration characteristics (H71).
 Enable torque limiter (F40, F41, E16, E17, and H73).
 Set the rated voltage (at base frequency) (F05) to "0" to improve the
braking capability.
Check if the overvoltage alarm occurs after rapid acceleration.
 Increase the acceleration time (F07, E10, E12, and E14).
 Select the S-curve pattern (H07).
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.
Check if the DC link bus voltage was below the protective level when
the overvoltage alarm occurred.
 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.
Prevent the inflow of high-frequency current.
 Apply control measures at the high-frequency current side.
 In some instances, this can be improved by removing the E1 and E2
screws. In this case, the EMC filter will no longer function, and the
inverter will no longer conform to EMC standards. Please contact
Fuji Electric if these screws are removed.
What to Check and Suggested Measures
 Release the alarm.
 If you want to restart running the motor without treating this
condition as an alarm, set F14 to "3," "4," or "5," depending on the
load type.
Check if the power to the inverter was switched back to ON while the
control power was still alive. (Check whether the LEDs on the keypad
light.)
 Turn the power ON again after all LEDs on the keypad go off.
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