Oil Circuit Breaker

The arrangement permits two advantages firstly the current breaking chamber requires a small volume of oil which is just enough for arc excitation secondly, the amount of oil to be replaced as the in the supporting chamber does not get contaminated the arc.
The single phase oil circuit breaker, there are only one moving contact. But HTM branch dehiwala has three phase oil circuit breaker. There are six moving contacts. Their supporting chamber and circuit breaking chamber made having metal. But single phase OCB supporting chamber made porcelain. Three phase OCBis very heavily we can’t moving it very easily.

Earth Fault Protection

• Earth fault current may be limited.

• Sensitivity and speed requirement may not be met by over current relays.

• Use separate earth fault relay

• Connect to measure residual (zero sequence) current.

• There fore can be set to values less than full load current.

Generator Protection

Generator protection

* Over current protection
* Short circuit current protection
* Earth fault protection
* Differential Current protection
* High voltage Protection
* Under voltage protection
* Under frequency protection
* Over Frequency protection
* Reverse power protection

Mainly Genarator set can be divided into two part

1. Engine
2. Alternator
   

Generator SET

A Generator set has five systems. for a good condition of a generation of electricity, they should maintenance properly.

• Starting System

• Fuel System

• Exhaust air System

• Lubrication oil System

• Cooling System

Earthing System

Panel boards are selling several Countries then earthing systems and main Bus bar arrangement are changed each country.

Type of System Earthing

01. TN system:

TN power system have one point directly earthed, the exposed conductive parts of the installation being connected to that point by protective conductors. Three types of TN systems are recognized, according to the arrangement of neutral and protective conductors,

(a) TN-S System – A system having separate neutral and protective conductors throughout

(b) TN-C-S System – A system in which neutral and protective function are combined in a single conductor in a part of system.

(c) TN-C system - A system in which neutral and protective functions are combined in a single conductor throughout.

02. TT System -

The TT power system has one point directly earthed, the exposed conductive parts of the installation being connected to earth electrodes electrically independent of the earth electrodes of the power system,

03. IT System -

The IT power system has no direct connection between live parts and earth, the exposed conductive parts of the electrical installation being earthed

Panel Designing

Panel designing process we need following details. Because panel is depended in these conditions.

· The "Form Type"

· Degree of protection (IP)

· Panel Colors

· Earthling System

· Short Circuit Time Duration

· Fault Current

And Single line diagram or bill of materials (Number of incoming and outgoing feeders) details.