Generator and Alternator

By Ship Electrical Engineer Ather Rizvi's Lecture on 

Generator and Alternator 

Fuel Lever Micro Switch on the governor (red in colour) is used to stop the generator from starting and stopping it in case of emergency. One of the few reasons for the generator not getting start is this lever being in the wrong position. It is one of the majour safties of the generator and has to be checked before the starting of the generator for its working.

Lube Oil cooler is used to maintain the temperature of the lube oil.
There are 4 different types of pressure switches

1. Lubeoil inlet low pressure Alarm.
2. Standby lubeoil inlet auto start.
3. Lubeoil inlet low pressure Switch.
4. Cool F.W. inlet low pressure Alarm.
5. Flywheel lever has two main functions.
6. To stop the generator in case of emergency.
7. Priming the genreator before starting or after changing the lube oil.

Drain tank is present on either side of the generator to accumulate the oil leaking from any part of the generator. It has a float switch which is responsible for intiating alarm when the tank is full.
Electrical Side of the Generator consists of Following parts:

1. Exciter
2. Alternator
3. Alternator is further devided into following parts:
4. Stator
5. Rotor
6. Diode
7. Armature
8. Heater to remove moisture and dampness from armature.
9. The control pannel consists of following main parts

A.C.B. (Air Circuit Breaker): Light of ACB turns on when the generator gets on load.
Bus Bars: Current generated enters the bus bars in three phases and then transmitted to the starter pannel. For a 3 phase generator there are 3 bus bars labled R, S, and T. In case of motor they are labled as U,V and W.

Reverse Power Relay: R.P.R. is used to prevent the generator converting into motor. It is tested by using synchronoscope. When two generators are run in parallel synchronoscope is used to synchronise their voltage, current and most importantly phase difference. For testing R.P.R. synchronometer is used to transmit voltage generated from say generator 1 to generator 2. If R.P.R. trips means that it is working properly. R.P.R. has a reset button which can be used to reset in case of a trip.

Synchronoscope: It is used to synchronise the phase difference and voltage developed by one or more generators in parallel. It is done by lowering the r.p.m using the governor and then synchronise the supply when the needle is at 0. In case of Auto it is all done by itself.

Voltage Regulator: It is used to increase or decrese the volatage to reach the desired amount. It can only increase or decrease small amount of voltage.

Preferential Trip: It is used to supply the current to the appliances.

Generator and its Parts.

By Chief Engineer Riaz Marghoob's Lecture On

Generator and its parts

It was the Daihatsu Generator.


There are two sides of the generator.
Electrical Side. (part after the flywheel)
Mechanical Side.

MECHANICAL SIDE
Cylinder Head is the top cover of the cylinder and contains following parts.
Rocker Arm.
Cylinder Relief Valve.
Exhaust Valve.
Air Starting Valve.
Fule injector.
Indicator Cock. (Indicates the inside position of the cylinder)
Push Rod
Turbo Charger is attached with the generator and is responsible for removing the burnt gasses from the cylinder and filling it with the fresh air. The more the fresh air in the cylinder the more will be the generator's efficiency.


Sump at the lower part of the engine contains lube oil for lubrication of Crank Pin Bering, main Bearing, cross head and Piston and cylinder liner.


There are two types of lubrication methods:
Splash Lubrication.
Forced Lubrication.

Splash Lubrication:

Splash lubrication takes place by the splashing due to the movement of the crank shaft.



Forced Lubrication:

For forced lubrication lube oil pump is required which pumps the lube oil through the connecting rod into the gudgeon pin hole through which it is released and lubricates the area between the piston and cylinder liner.



In both cases lube oil filter is attached to remove any impurity from the lube oil.


Fule pump is placed on the right hand side of the governor and is used to pump the fuel in the pipe over the cylinder head


Like a lube oil filter there is also a fuel oil filter which is used to filter the fuel oil.


Lube oil cooler is present to maintain the temperature of lube oil.


Piston contains two different types of ring attached in differnt combination depending upon the construct.
Compression Ring.
Scrapper Ring Or Oil Ring

Compression Ring:

It is used to restrict the hot gasses from entering into the sump.



Scrapper Ring:

It is responsible for creating a film of lube oil and scrap the lube oil into the sump from the liner.



Before attaching the ring make sure of the correct side of the ring to be at the top. Some times it is written on the ring "This Side Top."


Camshaft is present above the crank shaft and operates the rocker arms above the valve via push rod. It operates the push rod which further operates the rocker arm which further operates the spring loaded valves on cylinder head.

FOR ELECTRICAL SIDE PLEASE REFFER TO DOC. 1 ATHER RIZVI's LECTURE.

Written by Ali Ahmed