A ship cannot remain “Live” without a Generator – the lifeline and power production plant of the vessel. A generator on ship is a combination of two separate systems – an alternator and a prime mover whose capacity depends upon the number of machinery or power consuming items fitted on the ship.
What is Alternator?
An alternator is an electro-mechanical device comprising of stator, rotor winding and an external exciter for supplying excitation voltage. Alternator generates electricity when coupled with a prime mover.
Alternator on a ship is exposed to harsh weather and sea conditions, due to which, its capacity and efficiency tends to reduce. It is very important to have proper maintenance on the alternator part of the generator as per planned maintenance or as and when required.
Following Points are to be considered while Carrying Out Maintenance on Alternators:
Before starting any maintenance work on the alternator, all safety precaution should be taken and the alternator should be shut and locked down. Also, post notice and ply cards on relevant places and alternator heater to be isolated.
- Clean the alternator ventilation passage and air filter.
- Check the Insulation resistance of stator and rotor winding.
- Air gap between stator and rotor to be checked and maintained between 1.5 to 2 mm.
- Slip rings to be checked for even wear down to be renewed if required.
- Carbon brushes to be clean and checked for free movement.
- The brush contacting pressure to be checked by spring balance.
- Automatic Voltage Regulator to be checked and cleaned off oil and dust.
- The lube oil level of pedestal bearing to be maintained and renewed as per planned maintenance.
- A vacuum cleaner can be used to remove dust accumulated in the inner parts of alternator.
- The terminal box cover gasket to be checked for proper oil and water tightness.
- All the connection in the terminal box to be tightened properly.
- Cable gland to be checked for integrity.
- Forced Ventilation around alternator must be maintained all the time.
- Check heater for proper operation.
- The foundation bolts of the alternator to be checked for tightness.
After maintenance is performed, a no load test should be carried out and general condition such as noise, temperature, voltage generated etc. of the alternator should be observed and noted.