Electrical Maintenance, Fault Finding and Troubleshooting
Maintenance types
Preventive maintenance follows a schedule: cleaning, tightening, insulation checks and lubrication. Predictive maintenance uses trends such as vibration, thermography and insulation resistance. Breakdown maintenance is reactive and costly. Lockout-tagout, proving dead and permit-to-work are mandatory before intervention.
Fault-finding method
- Gather the symptom and history.
- Isolate and prove dead.
- Inspect for loose terminals, burnt insulation, moisture and mechanical damage.
- Test in a logical half-split sequence: supply, control circuit, load.
- Repair, retest and record.
Common faults: open circuit (no continuity), short circuit (low resistance, tripping), earth fault (low insulation to earth), overload (high current) and loose connection (intermittent operation, heat).
Worked example
A motor trips its overload after a few minutes. Check supply voltage and phase balance, clamp the running current against nameplate FLC, megger the winding to earth, and inspect bearings and ventilation. If current is balanced but above FLC, the cause is mechanical overload or a blocked fan; if one phase current is high, suspect a winding or supply imbalance.
Traps
Meggering a circuit still connected to electronics, failing to discharge capacitors, and replacing a fuse or resetting an overload without finding the cause. A tripping MCB is evidence, not a nuisance.