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Electrical machinery condition monitoring

MEO Class 2
UK EOOW
UK Management
ETO
MEO Class 4

times asked: 57; times asked
questions: 14; questions
last asked: 2026; last asked

The slides, written out

AI-drawn illustration. Simplified to explain the idea, not to scale.

Slide 1 · LEARN

LEARN APPLY SAIL AHEAD SMALL CHECKS. BIGGER RELIABILITY. ELECTRICAL MACHINERY CONDITION MONITORING Keep it healthy. Keep it running. MEASURE MONITOR PREVENT RELIABLE OPERATIONS SAFER VOYAGES

Slide 2 · ELECTRICAL MACHINERY

ELECTRICAL MACHINERY CONDITION MONITORING Keep it reliable. Prevent unexpected failures. For electrical machinery such as: Electric Motors | Alternators Two practical parameters to record 01 INSULATION RESISTANCE Assesses the condition of electrical insulation. MΩ 02 TEMPERATURE Tracks winding and bearing thermal condition. SUPPORTING PARAMETER VIBRATION A mechanical measurement that provides valuable information about bearings, imbalance, misalignment and looseness. KEY TAKEAWAY If the question forces you to choose two: Insulation Resistance + Temperature These are strong practical choices for assessing electrical-machine condition. Ref: IEC 60034-1:2026 | IEC 60034-27-4:2018 LEARN APPLY SAIL AHEAD

Slide 3 · ELECTRICAL MACHINERY CONDITION MONITORING

ELECTRICAL MACHINERY CONDITION MONITORING 02 INSULATION RESISTANCE Assesses the condition of electrical insulation. LEARN APPLY SAIL AHEAD HOW IS IT MEASURED? Use an insulation-resistance tester ("Megger" type) which applies a DC test voltage and measures the resistance. Measure between winding and earth. Where applicable, also between phases or other insulation barriers. Use the test voltage as per manufacturer's instructions and applicable standards. INSULATION TESTER > 1000 MΩ BEFORE TESTING ISOLATE LOCK OUT TEST DISCHARGE Ensure the equipment is de-energised and isolated. Follow safe working procedures (e.g. lock out tag out). After testing, discharge the windings safely to earth (as per manufacturer's instructions). Do not apply a test voltage that could damage the equipment. WHAT DOES IT REVEAL? A falling trend may indicate deterioration of the insulation condition. Possible contributors include: Moisture or condensation Contamination (salt, dust, oil) Ageing of insulation Insulation damage (thermal, mechanical, electrical) Adverse operating environment TYPICAL TREND Insulation Resistance (MΩ) Time Trend analysis provides more useful condition information than relying on a single reading. KEY TAKEAWAY Regular insulation resistance measurements and trend analysis help identify changes in insulation condition. Ref: IEC 60034-27-4:2018 | IEC 60034-1:2026

Slide 4 · 03/04

ELECTRICAL MACHINERY CONDITION MONITORING LEARN APPLY SAIL AHEAD 03 TEMPERATURE Tracks winding and bearing thermal condition. WHAT TO MONITOR? WINDING TEMPERATURE BEARING TEMPERATURE • Winding temperature • Bearing temperature • Temperature trend during operation HOW IS IT MEASURED? Embedded temperature detectors (RTDs, thermistors or other suitable detectors), where fitted. Resistance method or other approved temperature measurement methods, as applicable. Thermometer or thermal imaging for accessible surface temperatures. RTD / Thermistor Temperature meter (resistance method) IR / Thermal camera WHAT CAN A RISING TEMPERATURE INDICATE? WINDING TEMPERATURE ↑ • Overload or excessive load • Restricted cooling or inadequate ventilation • Unbalanced operating conditions • Internal electrical or winding abnormalities BEARING TEMPERATURE ↑ • Abnormal bearing or operating condition • Investigate lubrication, loading, alignment and cooling as applicable IMPORTANT IR / thermal camera measures ACCESSIBLE SURFACE TEMPERATURE. It does NOT directly measure the internal winding hot-spot temperature. KEY TAKEAWAY Monitor temperature trends against the machine's specified limits and operating conditions. Ref: IC 60034-1:2026

Slide 5 · 04/04

LEARN APPLY SAIL AHEAD ELECTRICAL MACHINERY CONDITION MONITORING 04 VIBRATION A key indicator of mechanical condition. Helps detect changes related to bearings, imbalance, misalignment and looseness in rotating machinery. HOW IS IT MEASURED? • Measure vibration at defined locations on the bearing housing or other appropriate machine locations. • Measurements are taken in horizontal, vertical and axial directions as applicable. • Use the same measurement locations for repeat readings to make trend comparison meaningful. Vibration Sensor Vertical Axial Horizontal WHAT CAN RISING VIBRATION INDICATE? Bearing deterioration Unbalance Misalignment Mechanical looseness IMPORTANT TO NOTE • Vibration levels should be evaluated using an applicable standard such as ISO 20816-3 for relevant machinery types and operating conditions. • ISO 20816-3 applies to specified industrial machinery (including flexible-coupled electric motors) and has limitations (e.g. usual power and speed ranges). • The standard provides vibration measurement and evaluation guidance. Detailed fault diagnosis (e.g. bearing faults) should use manufacturer guidance and additional diagnostic tools. Typical Vibration Trend Vibration Level (mm/s) Time A rising trend indicates a change in machine condition and should be investigated. WHY IS IT USEFUL FOR ELECTRICAL MACHINERY? Mechanical and electrical conditions can interact. A bearing problem can lead to increased vibration, abnormal operating condition and possible secondary effects on the machine. KEY TAKEAWAY Regular vibration monitoring and trend analysis help identify developing problems and support reliable operation. Ref: ISO 20816-3:2022 | ABB Motor Condition Diagnostics (Guidance)

In exams

Asked 57 times across 14 different questions, most recently in 2026. Asked most in MEO Class 2 (25), UK EOOW (19), UK Management (6), ETO (4).

Drafted by SailR from our daily lessons. AI-drawn illustration. Simplified to explain the idea, not to scale. Last updated 19 Oct 2026.

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