The Essentials Of Substations, Electrical Equipment and Busbar Arrangements

Introduction to substations

Electrical power systems nowadays are generated, transmitted, and distributed in the form of alternating current. The electric power is produced at the power stations which are located in suitable places, generally quite away from the consumers.

It is delivered to the consumers through a large network of transmission and distribution. At many places in the line of the power system, it may be desirable and necessary to change some characteristics (e.g., voltage, AC to DC, frequency, power factor [pf], etc.) of electric supply.

For that, in between the power station and ultimate consumer, a number of transformations and switching stations have to be created. These are generally known as substation.

Contents:

1. What Is the Substation?
2. Classification of Substations:
   1. According to Service Requirement
   2. According to Constructional Features
3. Comparison Between Outdoor and Indoor Substation
4. Transformer Substations
5. Equipment in a Transformer Substation
6. Busbar Arrangements in Substations
7. Key Diagram of 11 kV/400 V Indoor Substation

1. What is the substation?

The assembly of apparatus used to change some characteristic (e.g., voltage, AC to DC, frequency, pf, etc.) of electric supply is called a substation. Substations are important part of power system. The continuity of supply depends to a considerable extent upon the successful operation of substations.

The following are the important points which must be kept in view while laying out a substation:

1. It should be located at a proper site. As far as possible, it should be located at the center of gravity of load.
2. It should provide safe and reliable arrangement. For safety, consideration must be given to the maintenance of regulation clearances, facilities for carrying out repairs and maintenance, abnormal occurrences such as possibility of explosion or fire, etc.
   
   For reliability, consideration must be given for good design and construction, the provision of suitable protective gear, etc.
3. It should be easily operated and maintained.
4. It should involve minimum capital cost.

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2. Classification of substations

There are several ways of classifying substations. However, the two most important ways of classifying them are according to (1) service requirement and (2) constructional features.