Learning outcomes
- Explain the key principles of motor fault finding.
- Carry out a structured practical check or configuration task.
- Recognise common faults, risks and evidence needed for diagnosis.
Module 3 · Lesson 4
Motor fault finding
Diagnose failure to start, nuisance trips, overheating, vibration, low torque and incorrect rotation.
Before you begin
Drawings, meter, clamp meter, insulation tester and mechanical inspection checklist.
Safety: Use site procedures, approved test equipment and competent supervision. Never bypass a protection or interlock without formal control.
Step-by-step learning
- Separate the fault into supply, control, protection, motor or driven-equipment categories.
- Check command and permissives before dismantling equipment.
- Measure three-phase voltage and current under load and compare phase balance.
- Inspect coupling, bearings, ventilation, load and alignment before condemning the motor.
Ian's practical tips:
- Prove the driven machine can turn freely before repeatedly resetting an overload.
- Write down the first trip indication before anybody resets it.
Fault-finding questions
- What should be happening, and what evidence proves it?
- Where is the last known correct signal, voltage, state or process condition?
- What changed immediately before the fault?
- Can the system be divided into smaller testable sections?
Practical activity
Create a one-page test record for this lesson. Include expected values, measured results, equipment used, risks controlled, defects found and the final proven condition.