2151

Common Causes

• Defective inverter unit (control board error #1, bridge short #12, IPM protection #13, overcurrent #14, and most other # codes)
• Low ±12 V or 5 V control-board battery voltage (#2, #11) — if several inverter units alarm together, suspect the power unit
• Corrupt or incompatible optional program file (#3)
• Motor or wiring fault causing overcurrent (#14) or IPM trip (#13)

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code #1 = Control board error; code shows the board error content; code #2 = ±12 V control board battery voltage drop; code #3 = Optional program file error; code: 1=ID 'OPF1' error, 2=end code 'ED' error, 3=sum check error, 4=board name error; code #11 = 5 V control board battery voltage drop; code #12 = Inverter bridge shorted; code #13 = IPM protective function activated; code #14 = Motor overcurrent; code #20-#25 = INT/INT5/INT4/INT3/INT2/INT1 loop error
2. 2Record the character string (# number) and code shown on screen — the # value directs the entire diagnosis.
3. 3#2 or #11 (battery voltage drop): if multiple inverter units alarm at once, check the power unit output before touching individual inverters.
4. 4#3 (OPF error): the code identifies the file fault (1=bad 'OPF1' ID, 2=bad 'ED' end code, 3=sum check, 4=board name) — reload the correct optional program file or verify it matches the inverter unit.
5. 5#12, #13 or #14 (bridge short, IPM protection, overcurrent): lock out power and allow the DC bus to discharge, then check motor power cable and motor windings for shorts or ground faults before condemning the inverter unit.
6. 6#20–#25 (INT loop errors) and #27–#42 (CPU/memory/interrupt errors): point to the inverter unit control board — reseat connectors, then replace the inverter unit if the fault persists.
7. 7If the fault returns after these checks, record the alarm number, character string, code and object and contact Okuma service.