Learning outcomes
- Explain the key principles of systematic fault-finding method.
- Carry out a structured practical check or configuration task.
- Recognise common faults, risks and evidence needed for diagnosis.
Module 14 · Lesson 1
Systematic fault-finding method
Use symptom definition, evidence, divide-and-conquer testing and controlled restoration instead of guesswork.
Before you begin
Fault report sheet, drawings and safe test equipment.
Safety: Use site procedures, approved test equipment and competent supervision. Never bypass a protection or interlock without formal control.
Step-by-step learning
- State the exact symptom, first occurrence and operating context.
- Check alarms, events, recent changes and operator observations.
- Divide the system into power, control, communications, field device and process sections.
- Prove each hypothesis with one controlled test and record the result.
Ian's practical tips:
- Change one thing at a time. Multiple simultaneous changes destroy evidence.
- The fault is not fixed until normal operation and protective functions are both proven.
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.