Yaskawa GA500 fault oC: Overcurrent
Fault oC on a Yaskawa GA500 is Overcurrent: the drive sensors detected output current above the specified overcurrent detection level. Yaskawa lists heavy load, damaged motor insulation, shorted or grounded motor cable, short acceleration time, wrong V/f pattern, high torque compensation and starting onto a coasting motor among the causes.
Diagnose this with AI
Try Free Drive Diagnostic Upload a keypad photo, the fault history or a parameter export from your Yaskawa GA500. InduQT compares the evidence and suggests the next useful checks.
When it happens
- Instantly at start
- During acceleration
- Starting onto a coasting motor
- On a load step or when an output contactor switches
- During overexcitation deceleration
Likely causes and checks
1Motor cable short or ground, or damaged motor insulation
- Points to it
- Trips the instant the drive runs, even unloaded; may alternate with GF or SC.
- Check
- Disconnect the motor at the drive and megger cable and motor; measure cable-to-ground resistance as the manual directs.
2Acceleration time too short for the inertia
- Points to it
- Trips partway through the ramp; heavier loads trip sooner.
- Check
- Increase C1-01 (or C1-03/C1-05/C1-07) and the S-curve C2-01 to C2-04, then compare U2-05 output current at fault.
3Run command while the motor is coasting
- Points to it
- Trips at restart on fans or flywheels that are still turning.
- Check
- Set b3-01 = 1 (speed search at start) or start only after the motor has stopped.
4V/f pattern or torque compensation too high
- Points to it
- Trips at low speed with little load in V/f mode.
- Check
- Check E1-04 to E1-10 against the motor and reduce C4-01 [Torque Compensation Gain].
5Output contactor switching while the drive outputs voltage
- Points to it
- Trips coincide with a contactor between drive and motor operating.
- Check
- Change the sequence so the contactor does not switch while the drive is outputting voltage.
6Load too heavy or drive undersized
- Points to it
- Measured current above the drive rating; motor larger than the drive’s maximum applicable motor.
- Check
- Measure motor current and compare with the drive and motor nameplate ratings.
Telling it apart
- oC is an instantaneous overcurrent. oL1 is the motor’s time-based overload and oL2 the drive’s. SC (Short Circuit/IGBT Failure) indicates an output short or IGBT failure.
- Instant trip at start points to cable, motor or a coasting motor. A trip partway through the ramp points to C1-01 and inertia.
- V1000 equivalence: the V1000 Technical Manual (SIEP C710606 18F) lists oC with the same name and largely the same causes (insulation, cable short, heavy load, short accel or decel time, output contactor, V/f setting, torque compensation, coasting restart).
Relevant parameters
| Parameter | Name | Why it matters |
|---|---|---|
| C1-01 | Acceleration Time 1 | Default 10.0 s; C1-03/C1-05/C1-07 are alternates. |
| C2-01 to C2-04 | S-Curve Characteristics | Softens the start and end of the ramp. |
| C4-01 | Torque Compensation Gain | Reduce if excessive. |
| b3-01 | Speed Search at Start Selection | 1 = enabled; for starting onto a coasting motor. |
| C6-02 | Carrier Frequency Selection | Lower it when the motor cable is long, per the manual. |
Evidence to collect
- Keypad photo and U2-05 output current at fault
- When in the sequence it tripped
- C1-01, C2-01–C2-04, C4-01, E1-04–E1-10 and b3-01
- Control method A1-02 and motor data
- Insulation results with the motor disconnected
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