This document summarizes key aspects of marine electrical systems including: 1. Electrical safety hazards such as electric shock, overcurrent, and thermal hazards. 2. Common electrical instruments for measurement such as ammeters, voltmeters, and ohmmeters. 3. Procedures for testing continuity, resistance, and insulation of wiring, cables, and equipment. 4. Types of tests including continuity tests to check current paths, resistance tests for equipment windings, and insulation resistance tests to check insulation quality.

1. Marine Electrical System
Integrity
Oladokun Sulaiman Olanrewaju

2. Electrical Safety
• Electric shock
• Over current
• Thermal hazard
• Safely procedure

3. Electrical instrument
Electrical Instrument • Measuring instruments
• Analogue • Ammeter
• Digital • Voltmeter
Measurement • Ohmmeter
-voltage • Multimeter
-Current • Insulation tester
- Resistance • Wattmeter
- Power • Watt-hour meter
• Power factor meter
• Frequency meter
• Voltage indicator
• Phase sequence indicator
• Earth loop tester
• Earth resistance tester
• Phase stick tester

4. Meter specification
• Types of meter
• Max measuring value
• Accuracy
• Operating temperature
• Resolution
• Types of supply (AC or DC)
• Connection method
• Percentage error
• Maximum surge current
• location

5. Continuity test
• to check condition of current path
• Correct condition
• Condition of circuit and equipment
• For ie cable, coil, winding
-ohmmeter test
Good- low ohm reading
Malfuntion- high or infinit ohm reading
-buzzer test
-lamp test

6. Resistance test
• To check condition of equipment winding or
coil
Good- small resistance- 3 phase expected to have
equal resistance value

7. Insulation resistance test
• Check condition of insulation material
Types-
Hand cranking
Battery operated
Acceptable values of output
250V DC - extra low voltage – 0.5 M- Ohm
500V DC - <500V - 0.5 M- Ohm
1000V DC – 1000V – 1.0 M-Ohm

8. Test procedure
• For equipment - Remove equipment from circuit
• Testing
-1 phase- between coil or winding to ground or body
-3 phase- between winding to winding or pole to pole
-Between each winding
For cable or circuit
Remove cable /circuit from supply and load
Testing
1 phase- between phase to neutral, phase to earth and neutral to
earth
3phase- between phase to phase, each phase to neutral, each
phase to body or earth, neutral to earth

9. Current injection test
• Primary injection
CT ratio, connection, polarity
Stability and sensitivity of protection
• Secondary injection
• To check relay performance- operating current
at various TMS and PMS using injection tester

10. Pressure test
• Insulation property of HV
• - 2 times voltage is supplied for 1min of AC,
and 10min of DC

11. Earthling testing
• Test earthing system items earth loop
independence, earth electrode resistance