MachineryFix

Problems We Solve · Drives & Motor Control

Drive powered up but the motor won't turn?

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

Drive On But Motor Won't Run

A drive that's healthy and displaying normally but won't spin the motor is usually missing a run command, a permissive or an enable — not broken. The fault is in the command chain (run signal, enable, references, safe-torque-off) far more often than in the power stage.

We diagnose why a VFD or servo drive sits ready but idle — checking the start/enable logic, references, STO circuit and parameters — and get the motor turning without unnecessary replacement.

02 / Diagnosis

Likely causes

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

DX_01

Missing run / enable command

The drive is in local when it needs remote (or vice versa), the run signal isn't arriving from the PLC, or a hardwired enable is open. The drive is waiting, correctly, for a command it isn't getting.

DX_02

Safe-torque-off (STO) open

The STO safety inputs are not satisfied, so the drive inhibits output by design. A jumper removed, a safety-relay fault or a wiring change will hold STO open.

DX_03

Zero / missing speed reference

The frequency/speed reference is at zero or not arriving — an analog input fault, a broken potentiometer, or a fieldbus reference not being written.

DX_04

Parameter / control-mode issue

A control-source parameter set wrong after a reset or replacement, or a mis-configured command source, leaves the drive ready but uncommanded.

DX_05

Interlock not satisfied

An external permissive — brake feedback, a downstream ready signal, a process interlock — is blocking the run. The drive is enforcing a condition the machine defines.

03 / Onsite

What our technician checks

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

  1. 01Confirm the run/enable command reaches the drive terminals
  2. 02Check local/remote and command-source parameters
  3. 03Verify the speed/frequency reference value and source
  4. 04Test the STO circuit and safety inputs
  5. 05Trace external permissives and interlocks

04 / Fix it

Related services

The services that resolve this fault.

VFD RepairServo Drive RepairVFD / AC Drive CommissioningPLC Repair & Programming

05 / Questions

Frequently asked questions

The drive shows 'ready' but nothing happens on start. Is it faulty?+
Usually not — a drive that displays 'ready' has a working power stage and is waiting for a valid command. The fault is normally a missing run/enable signal, an open STO circuit, a zero speed reference, or a wrong control-source parameter. We check the command chain before suspecting the hardware.
After we replaced the drive it powers up but won't run. Why?+
A replacement drive often has default parameters — the command source, control mode or STO configuration may not match your machine. We set the parameters to match the original commissioning so it responds to your run command and reference correctly.

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

Drive On But Motor Won't Run? 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