Yaskawa GA500 trips GF at startup, what to check first?
My Yaskawa GA500 drive is tripping on a GF (Ground Fault) every time I try to start the motor. It happens as soon as the output switches on. What should I investigate first?
A Yaskawa GA500 Ground Fault (GF) indicates a current short to ground on the output side of the drive, exceeding 50% of the drive's rated current. This fault can be triggered by damaged motor insulation, a shorted motor cable, high leakage current from cable stray capacitance, or an internal drive hardware issue. It commonly occurs at startup, after washdowns, or with long motor cables.
Likely causes and checks
1Damaged Motor Insulation
- Points to it
- Overheating or moisture can damage the motor's insulation, causing a short to ground. This often results in the drive tripping immediately at startup.
- Check
- Disconnect the motor from the drive and measure the motor's insulation resistance. Replace the motor if the insulation is unsatisfactory or shows electrical conduction.
2Shorted Motor Cable
- Points to it
- The motor main circuit cable may be damaged or contacting ground, creating a short circuit. This can occur after physical damage or water ingress.
- Check
- Inspect the motor main circuit cable for any visible damage. With both ends of the cable disconnected, measure the resistance between the cable and the ground terminal. Replace the cable if electrical conduction is detected.
3High Leakage Current from Cable Stray Capacitance
- Points to it
- Long motor cables (over 100 meters) can have significant stray capacitance, leading to high leakage current that the drive detects as a ground fault, even if insulation tests pass.
- Check
- Decrease the carrier frequency (parameter C6-02) to reduce the effect of stray capacitance.
4Drive Hardware Problem
- Points to it
- If the ground fault persists even when the motor cable is disconnected from the drive output terminals, the issue likely lies within the drive's internal hardware.
- Check
- Contact Yaskawa for assistance. This may require control board or drive replacement.
Next check: Given that the fault occurs every time at startup, the most common cause is damaged motor insulation. You should start by disconnecting the motor from the drive and measuring its insulation resistance.
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