Transcript Slide 1
MOTORS AND STARTERS, EMERGENCY POWER AND ASSOCIATED EQUIPMENT (Adapted from:D.T. Hall:Practical Marine Electrical Knowledge) After checking through the IR test results list, a surveyor may ask to witness a repeat test on selected motors. A visual examination of a motor frame and terminal box will reveal any damaged or missing parts. General neglect will be suspected if the motor is covered with dirt, oil or rust. Totally enclosed fan ventilated (TEFV) induction motors require little attention as their windings are protected against the external atmosphere. The surveyor will be more likely to concentrate on motors with drip proof, weatherproof and deck-watertight enclosures. It may be necessary to open up such motors to check for ingress of oil and water which could damage insulation and cause internal corrosion. Special machines such as d.c. commutator or a.c. slip-ring types used, for example, on an electric windlass, must have their rotary contacts and brush gear checked. Cargo cranes and winches are not strictly part of a survey as they are not considered essential to the safety of the ship. A running test on a motor will reveal any vibration problems, undue noise and worn out bearings. On-load, the motor running current (shown on the ammeter at the starter) should be checked against the value indicated on the motor rating plate. With starters and associated control gear such as remote stop/start buttons, regulating resistors, etc., an inspection will check mainly for badly burned and misaligned contacts. The general condition of starter equipment will also be examined. This would include an inspection for loose connections, worn pigtails on moving contacts, badly carbonised arc-chutes and signs of overheating on coils, transformers and resistors. Dust and weather-proof sealing features on a starter must be in place and in a serviceable condition. Functional checks will test the normal operation of the starter from its local, remote and emergency control (if applicable) positions. Signal status lamps showing the motor/starter condition, e.g. running, off, tripped, etc., must be demonstrated as working correctly. Overcurrent trip settings should be compared with the motor full-load current (FLC) rating. Motor starter back-up fuse size and type may be checked against the ship's/manufacturer's drawings and the motor rating. Emergency Power and Associated Equipment Under survey: the operation of the emergency generator and/or battery power equipment. The emergency generator must be started, manually or automatically, while the initiation sequence and operation of starting equipment is observed. Electrical supplies taken from the emergency switchboard should be checked as receiving their rated voltage, current and frequency when powered from the emergency generator. Emergency lighting, fire pump and other emergency electrical equipment must be functioning correctly. Electrical interlocking arrangements between main and emergency switchboard must be checked. Auto-start initiation relays, whether voltage or frequency operated, will be examined and tested. The ship's emergency battery installation and its charging rectifier will be examined. In particular the battery environment must be dry and well ventilated. The battery tops must be clean with terminal posts and connections appearing free from corrosion. Grease all connections with petroleum jelly. Battery electrolyte should be at its proper level and have the correct value of specific gravity (SG) as checked on a hydrometer. Safety notices and personnel safety clothes (gloves, apron and goggles) should be available adjacent to the batteries. The ventilation arrangements for the battery locker will be checked. Battery charging equipment should he given the normal checks for dirt, overheating, loose connections and correct functioning of indicators, instruments and alarms.