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 works as a matchmaker between higher voltage level transformers and lower voltage level transformers connecting 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 be interested to read:

01. Copper and Aluminum Bus-bar Size Selection Chart.

02. METAL-CLAD BUS BARS AND CONNECTIONS.

The schematic line diagram for the bus-Bar arrangement for each type of scheme is described below:

Single Bus-Bar Arrangement:

The 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 that needs maintenance or goes outage due to fault, the entire substation is lost or go in shutdown.

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

Main and Auxiliary Bus-Bar Arrangement:

To overcome the disadvantages of a single bus-bar arrangement, additionally, a bus-coupler circuit is arranged as an Auxiliary bus that can be used during the 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 called Auxiliary Bus energized from the main bus bars through a bus coupler circuit. 

This bus-bar scheme also suffers like a 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 is widely used for 132kV substations.

Double Bus-Bar Arrangement:

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

The advantage of the double bus-bar arrangement is 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 shut down.

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

Double Main and Auxiliary Bus-Bar Arrangement:

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

One-and-a-Half Breaker Arrangement:

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

 Normally both bus bars are in operation if a fault occurs then the associated circuit breaker opens and the fault remove.

Easily any circuit breaker can be taken out in need of any maintenance without causing an 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 outgoing feeders is in opposite directions.


This scheme has been used in the 400 kV substations.

Hope, you got the idea to select the arrangement for your bus-bar system.