VSD trips on earth/ground fault
The drive trips with an earth/ground-fault code — typically the instant it outputs — indicating leakage to earth on the motor or output cabling.
Safety first
An earth-fault trip can indicate damaged insulation and a shock risk. Isolate, discharge the bus, and prove dead before testing output cabling. Don't reset repeatedly into an earth fault.
Isolate, lock out / tag out, and prove dead before working unless a live test is specifically required, authorised, and carried out under proper supervision. Always follow local regulations, your site procedures, and the equipment manufacturer's documentation.
Apprentice mode
Full walk-through — the why, what readings mean, mistakes & safety.
Likely causes
Ranked from most to least likely.
- 1
Motor or output cable insulation fault to earth
Most likelyDamaged or damp insulation on the motor or its cable leaks to earth the moment the drive outputs.
- 2
Excessive cable length / capacitance
#2Very long output cables have high capacitance to earth that can look like an earth fault, especially on start.
- 3
Moisture in motor/junction boxes
#3Water ingress in the motor terminal box or a junction provides a leakage path.
- 4
Output wiring fault
Least likelyA pinched or damaged output conductor contacting earth.
Reports are saved on this device to reflect what you actually find.
Testing sequence
Work through one test at a time. Expected reading and what each result means.
On the tools? Job Mode shows one test at a time with thumb-sized buttons — your place and readings carry straight over.
Enter Job ModeIsolate, lock off, discharge the bus, disconnect the output cable at the drive, and insulation-test motor + cable to earth per procedure.
High insulation resistance to earth on motor and cable.
Insulation good — suspect cable length/capacitance or the drive's detection.
Low insulation to earth — locate and repair the leakage (motor or cable).
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
VSD earth-fault trip
→ step 2 - 2decision
Is motor + cable insulation to earth healthy?
Yes→ step 3No→ step 4 - 3decision
Are terminations dry and clean?
Yes→ step 5No→ step 6 - 4result
Low insulation — locate and repair the leakage.
- 5decision
Is output cable length within the drive's allowance?
Yes→ step 7No→ step 8 - 6result
Dry/clean and reseal the terminations.
- 7result
Refer to drive docs on earth-fault detection.
- 8result
Excessive length/capacitance — apply long-cable measures.
Common mistakes apprentices make
- Resetting repeatedly into an earth fault instead of isolating and testing.
- Testing with everything connected and not isolating motor vs cable.
- Overlooking moisture in the motor terminal box.
- Ignoring very long output cables as a cause.
When to stop & escalate
A confirmed insulation fault is a repair (motor or cable) — don't run until fixed. Long-cable mitigation (output filters/reactors) is a design consideration to plan properly.
If you're past your competence, authorisation, or the safe limits of the job — stop and hand it on. There's no fault worth getting hurt over.
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Related faults
VSD trips on overcurrent / overload
The drive trips with an overcurrent or overload code — on start, on acceleration, or under running load. It may restart and trip again on the same point in the cycle.
Motor with low insulation resistance to earth
An insulation resistance test on the motor reads low to earth — a sign the winding insulation is degraded, damp, or contaminated, risking trips and failure.
RCD / RCBO keeps tripping
An RCD or RCBO trips repeatedly — immediately on reset, randomly during the day, or only when certain equipment runs. The earth-leakage protection is doing its job; something is leaking.
Learn the theory
How the gear and circuits behind this fault actually work.