Bus-Bar Arrengement Design upto 400kV Capacity Substation

Typical Bus-Bar Arrangement System for High Voltage and Extra High voltage up to 400kV Capacity Substations.

Bus-Bar actually work as a match maker between higher voltage level transformer and lower voltage level transformer connection others equipment to functional a co relation between them.

The commonly used bus bar schemes for high voltage and extra high voltage at 132kV, 230kV or 400kV Sub Stations are as below:
  1. Single bus bar;
  2. Main and Transfer bus bar;
  3. Double bus bar;
  4. Double main and transfer bus bar; 
  5. One and a half breaker scheme.

You may interrested to read:

The schematic line diagram for bus-Bar arrangement for each type of schemes are described below:

Single Bus-Bar Arrangement:

single bus-bar arrangement  is the simplest and easiest switching scheme in which each circuit is provided with one circuit breaker. 

This arrangement can ensure limited security against bus bar faults and no switching flexibility, as a result go into quite extensive outages of bus bar and frequent maintenance of bus bar isolators. 

In the single bus-bar scheme, in any bus-bar, isolator or other equipment need maintenance or go outage due to fault the entire substation lost or go in shutdown.

Another disadvantage of this switching scheme is that in case of maintenance of circuit breaker, the associated feeder has also to be shutdown.

Typical Single Bus-Bar Arrangement

Main and Auxiliary Bus-Bar Arrangement:

To overcome the disadvantages of single bus-bar arrangement, additionally a bus-coupler circuit is arranged as Auxiliary bus that can be used at main bus maintenance period without de-energizing the circuit controlled by that breaker as that circuit then gets energized through bus coupler breaker.

Main and Auxiliary Bus-Bar is technically a single bus bar arrangement with an additional bus bar which called Auxiliary Bus energized from main bus bars through a bus coupler circuit. 

This bus-bar scheme also suffer like single bus-bar system in the event of a fault on the main bus bar or the associated isolator, the entire substation is lost. 

This type of arrangement widely used for 132kV substations.
Typical Main and Auxiliary Bus-Bar Arrangement

Double Bus-Bar Arrangement:

Double Bus-Bar arrangement scheme is used to overcome the disadvantages of single or main and auxiliary bus-bar scheme. The schematic diagram is shown below where each circuit can be connected to either one of these bus bars through respective bus bar isolator. 

The advantage of double bus-bar arrangement in such away that the circuits can be switched on from one bus to the other on load. 

This scheme suffers from the disadvantage that when any circuit breaker is taken out for maintenance, the associated feeder has to be shutdown.

This bus-bar arrangement widely used in 220kV or 230 kV substations.

Typical Double Bus-Bar Arrangement

Double Main and Auxiliary Bus-Bar Arrangement:

Using double main and auxiliary bus-bar scheme, it is possible to overcome the limitation of double bus bar scheme.

In Double Main and Auxiliary Bus-Bar Arrangement the feeder is transferred to the Auxiliary bus during maintenance of its controlling circuit breaker without affecting the other circuits.

This Bus bar arrangement is generally used nowadays in 220 or 230kV substations.

Typical Double Main and Auxiliary Bus-Bar arrangement

One and a Half Breaker Arrangement:

In one and a half breaker arrangement scheme three circuit breakers are used for controlling two circuits which are connected between two bus bars.

 Normally both bus-bars are in operation, if fault occur then associated circuit breaker opened and fault remove.

Easily any circuit breaker can be taken out in need any maintenance without causing interruption.

The main advantage is to load transfer is achieved through the breakers and, therefore, the operation is simple.

The one and a half breaker arrangement is best for those substations which handle large quantities of power and where the orientation of out going feeders is in opposite directions.

This scheme has been used in the 400 kV substations.

Typical One and a Half Breaker Arrangement


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