MachineryFix

Problems We Solve · Drives & Motor Control

VFD keeps tripping on overcurrent or overvoltage?

Likely causes, what our technicians check onsite, and how to get it fixed — verified engineers across India, onsite in hours (under 4 in Hyderabad), 24/7.

Book a TechnicianCall +91 70751 47888

01 / Overview

VFD Keeps Tripping

A VFD that trips repeatedly is reporting a specific fault — overcurrent (OC), overvoltage (OV), overtemperature (OH), ground fault (GF) or undervoltage (UV) — and each points at a different cause. Clearing the fault and restarting without diagnosing it just repeats the trip, sometimes until something lets go.

We repair and re-parameterise every major drive — Siemens SINAMICS/MICROMASTER, ABB ACS, Schneider Altivar, Allen-Bradley PowerFlex, Mitsubishi FR, Delta and Yaskawa — reading the fault history and testing the power stage, DC bus, cooling and motor before we quote.

02 / Diagnosis

Likely causes

The handful of things that actually cause this — in the order we rule them out.

DX_01

Overcurrent (OC)

A failing IGBT leg, a shorted or breaking-down motor winding, a too-aggressive acceleration ramp, or a mechanical jam. We meter the IGBT stage and megger the motor to separate drive from motor.

DX_02

Overvoltage (OV)

Usually a braking problem — a decelerating load regenerating energy with an open or missing brake resistor/chopper — or supply overvoltage. Common on high-inertia loads with short deceleration times.

DX_03

Overtemperature (OH)

A clogged heatsink or a dead cooling fan, the single most common repeat-trip in dusty plant. The drive is fine; it just can't shed heat.

DX_04

Ground fault (GF)

Current leaking to earth on the output side — a motor winding breaking down to frame, or a damaged/damp output cable. Far more often a motor/cable fault than a drive fault.

DX_05

Undervoltage (UV)

Supply-side: phase loss, a loose incoming termination, or voltage sag when a big load starts elsewhere. Occasionally a failed pre-charge circuit in the drive.

03 / Onsite

What our technician checks

A methodical path to root cause — not a scattergun of part swaps.

  1. 01Read the fault history and identify the exact trip code
  2. 02Meter the IGBT power stage and DC-bus capacitors
  3. 03Megger the motor and output cable for shorts and ground faults
  4. 04Inspect heatsink, cooling fan and ambient conditions
  5. 05Review ramp times, current limits and brake-circuit parameters

04 / Fix it

Related services

The services that resolve this fault.

VFD RepairAC Drive RepairVFD Troubleshooting GuideSiemens VFD Repair

05 / Questions

Frequently asked questions

My VFD trips on overcurrent every time I start. Is the drive faulty?+
Not necessarily — recurring overcurrent is often a failing IGBT leg, but just as often a shorted motor winding or a ramp set too aggressively for the load. We meter the IGBTs, megger the motor and review the ramp/current-limit parameters before replacing anything, because swapping the drive without finding the cause usually repeats the fault.
Is it cheaper to repair the VFD or replace it?+
Component-level repair is typically a fraction of replacement cost, and for older or obsolete drives it's often the only option. If the power stage and control board are both damaged, or spares are unobtainable, we'll tell you replacement is the better call rather than quoting an uneconomic repair.

Written & reviewed by MachineryFix Engineering Team — last reviewed — questions? Call +91 70751 47888

VFD Keeps Tripping? Get a technician onsite.

Describe the fault and we'll match a verified specialist near you — onsite in hours across India, under 4 in Hyderabad. 24/7.

Book a TechnicianCall +91 70751 47888