Troubleshooting Guides · Free Tool

VFD Fault Finder (Vendor Neutral)

Choose the type of drive trip and get the usual causes, checks and fixes. Use your drive manual for exact fault codes.

OvercurrentOvervoltageOvertemperatureEarth fault

What do you see?

SymptomOvercurrent trip

Most likely causeAcceleration too fast

First checkTrips during start

Causes in order of likelihood

Cause	How to check	Fix
Acceleration too fast	Trips during start	Increase acceleration time
Motor or cable short	Megger motor and cable disconnected	Repair insulation
Mechanical jam or overload	Turn the load by hand	Clear the jam

Before You Start

Isolate and wait for the DC bus to discharge before touching terminals; verify with a meter.
Read the fault history and operating values at the trip.
Never megger with the drive connected; disconnect motor cables first.

VFD Fault Finder (Vendor Neutral): All Symptoms

Overcurrent trip

Likely cause	How to check	Fix
Acceleration too fast	Trips during start	Increase acceleration time
Motor or cable short	Megger motor and cable disconnected	Repair insulation
Mechanical jam or overload	Turn the load by hand	Clear the jam

Overvoltage trip

Likely cause	How to check	Fix
Deceleration too fast	Trips when stopping	Increase deceleration time
Overhauling load	Load drives the motor	Add braking resistor or regeneration
High supply voltage	Measure supply	Correct supply

Undervoltage trip

Likely cause	How to check	Fix
Supply dips	Check supply events	Ride through settings; supply fix
Loose input connection or blown fuse	Check input terminals and fuses	Repair
Failed rectifier or precharge	Maker diagnostics	Repair drive

Overtemperature

Likely cause	How to check	Fix
Blocked fan or filter	Inspect cooling	Clean or replace fan
High ambient	Measure panel temperature	Improve ventilation
Overload or high switching frequency	Check current and settings	Reduce load or frequency

Earth fault

Likely cause	How to check	Fix
Damaged motor cable	Megger cable disconnected	Replace cable
Moisture in motor	Megger motor	Dry and test motor
Long cable capacitance	Check cable length	Output reactor or filter

Motor overload

Likely cause	How to check	Fix
Load too high	Compare current with rating	Reduce load
Wrong motor data in drive	Check nameplate parameters	Correct parameters
Low speed self cooled motor	Long running at low speed	Forced cooling or derate

Key insight: note when the trip happens: during acceleration points to overcurrent settings, during deceleration to overvoltage, at steady speed to load or cooling.