Chapter 14 Fault Codes and DescriptionsME300 
 
14-5 
 
Cause  Corrective Actions 
Deceleration time is too short, 
causing too large regenerative 
energy of the load. 
1.  Increase  the  setting  value  for  Pr.01-13,  Pr.01-15,  Pr.01-17  and  Pr.01-19 
(deceleration time). 
2.  Connect brake resistor, brake unit or DC BUS to the drive. 
3.  Reduce the brake frequency. 
4.  Replace the drive with a larger capacity model. 
5.  Use S-curve acceleration/deceleration. 
6.  Use over-voltage stall prevention (Pr.06-01). 
7.  Use auto-acceleration and auto-deceleration (Pr.01-44). 
8.  Adjust braking level (Pr.07-01 or the bolt position of the brake unit). 
The setting for stall prevention 
level is smaller than no-load 
current. 
The setting for stall prevention level should be larger than no-load current. 
Power voltage is too high. 
Check if the input voltage is within the rated AC motor drive input voltage range, 
and check for possible voltage spikes. 
ON/OFF switch action of phase-in 
capacitor in the same power 
system 
If  the  phase-in  capacitor  or  active  power  supply  unit  acts  in  the  same  power 
system, the  input  voltage may surge abnormally  in a  short  time. In this case, 
install an AC reactor. 
Motor ground fault 
The ground short circuit current charges the capacitor in the main circuit through 
the power. Check if there is ground fault on the motor cable, wiring box and its 
internal terminals. 
Troubleshoot the ground fault. 
Incorrect wiring of brake resistor or 
brake unit 
Check the wiring of brake resistor or brake unit. 
Malfunction caused by interference 
Verify the wiring of the control circuit and wiring/grounding of the main circuit to 
prevent interference. 
 
ID No.  Display on LCM Keypad  Fault Name  Fault Descriptions 
9 
 
Over-voltage at 
constant speed 
(ovn) 
DC  BUS  over-voltage  at  constant  speed.  When  ovn 
occurs,  the  drive  closes  the  gate  of  the  output,  motor 
runs freely, and the display shows an ovn error. 
Action and Reset 
Action level 
230V series: 410 V
DC
 
460V series: 820 V
DC
 
Action time  Immediately act when DC BUS voltage is higher than the level. 
Fault treatment parameter  N/A 
Reset method  Manual reset 
Reset condition  Reset only when DC BUS voltage is lower than 90% of the over-voltage level. 
Record  Yes 
Cause  Corrective Actions 
Impulsive change of the load 
1.  Connect brake resistor, brake unit or DC BUS to the drive. 
2.  Reduce the load. 
3.  Replace the drive with a larger capacity model. 
4.  Adjust braking level (Pr.07-01 or the bolt position of the brake unit). 
The setting for stall prevention 
level is smaller than no-load 
current. 
The setting for stall prevention level should be larger than no-load current. 
Regenerative voltage of motor 
inertia 
Use over-voltage stall prevention function (Pr.06-01) 
Use a brake unit or DC BUS 
Power voltage is too high. 
Check if the input voltage is within the rated AC motor drive input voltage range, 
and check for possible voltage spikes. 
ON/OFF switch action of phase-in 
capacitor in the same power 
system 
If  the  phase-in  capacitor  or  active  power  supply  unit  acts  in  the  same  power 
system, the  input  voltage may surge abnormally  in a  short  time. In this case, 
install an AC reactor. 
Motor ground fault 
The ground short circuit current charges the capacitor in the main circuit through 
the power. Check if there is ground fault on the motor cable, wiring box and its 
internal terminals. 
Troubleshoot the ground fault. 
Incorrect wiring of brake resistor or 
brake unit 
Check the wiring of brake resistor or brake unit. 
Malfunction caused by interference 
Verify the wiring of the control circuit and wiring/grounding of the main circuit to 
prevent interference.