3154

Common Causes

• Incoming supply voltage drop, power failure, blown input fuse or momentary power interruption (low voltage case)
• Excessively high input voltage or faulty power unit (high voltage case)
• Power unit internal failure: converter overcurrent, shorted power element, or defective regenerative circuit
• Control power (+5V, +12V or -12V) out of tolerance inside the power unit
• Heat sink overheating or regenerative circuit overload from heavy duty cycle

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code X=0 = DC voltage alarm; ZZ data shows the detected DC voltage in hexadecimal (3.9V per unit); code X=1 = Abnormal input voltage; ZZ data shows the detected AC voltage in hexadecimal (3.1V per unit); code X=2 = Abnormal control power; ZZ data: 1 = +5V abnormal, 2 = +12V abnormal, 3 = -12V abnormal; code X=3 = Abnormal control status; ZZ data: 1 = converter overcurrent, 2 = abnormal power element, 3 = converter short circuit, 4 = abnormal regenerative circuit (power regenerative type), 5 = abnormal regenerative circuit (resistor discharge type); code X=4 = Overload in the regenerative circuit; code X=5 = Heat sink overheat; code X=6 = CPU error in the power unit; code Y bit3 = An alarm occurred in the power unit (warning signal status 0)
2. 2Read the code: the X digit is the alarm number (0 DC voltage, 1 input voltage, 2 control power, 3 control status, 4 regenerative overload, 5 heat sink overheat, 6 CPU error); the ZZ data gives the measured voltage or the detailed fault cause.
3. 3For X=1 (abnormal input voltage): measure the three-phase supply at the power unit terminals, check for a blown fuse in the input power circuit, and look for signs of a momentary power interruption or loose supply connections.
4. 4For X=2 (abnormal control power): the ZZ data tells which rail failed (1 = +5V, 2 = +12V, 3 = -12V); after lockout and DC bus discharge, suspect the power unit itself.
5. 5For X=3 (abnormal control status): the ZZ data points to converter overcurrent, a bad power element, converter short circuit, or a defective regenerative circuit (power regenerative or resistor discharge type); inspect the regenerative resistor and its wiring before condemning the unit.
6. 6For X=4/5 (regenerative overload or heat sink overheat): check the power unit cooling fans, clean the heat sink and filters, and reduce rapid repetitive accel/decel cycles before retrying.
7. 7If the fault points to the power unit itself, do not open it until input power is locked out and the DC bus has fully discharged; then record the alarm number, full code and object and contact Okuma service.