Learning outcomes
- Explain the key principles of intermittent faults and event reconstruction.
- Carry out a structured practical check or configuration task.
- Recognise common faults, risks and evidence needed for diagnosis.
Module 14 · Lesson 2
Intermittent faults and event reconstruction
Diagnose faults that disappear using timestamps, trends, event logs, vibration, temperature and temporary monitoring.
Before you begin
SCADA trends, PLC logs, network captures and data logger.
Safety: Use site procedures, approved test equipment and competent supervision. Never bypass a protection or interlock without formal control.
Step-by-step learning
- Synchronise clocks before collecting evidence.
- Build a timeline from operator report, alarms, PLC events and network logs.
- Look for shared causes such as supply dips, heat, vibration or communications loss.
- Install targeted monitoring with clear trigger conditions.
Ian's practical tips:
- Intermittent faults reward patience and timestamps, not random parts replacement.
- Preserve logs before rebooting equipment.
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.