My experience in drafting the layout & arrangement drawing of 33/11 kV distribution substation

Layouts and arrangements analysis

Medium voltage substations fall within the sub-transmission power system category, which feeds the bulk consumers directly or facilitates the secondary and tertiary distribution to small industrial and household consumers over an area after a suitable stepping down of voltage. Because of space and capital constraints, these substations need proper analysis of the various possibility of layouts and arrangements to make the optimal use of limited resources available.

In this article, we will share the most important design aspects for drafting the layout and arrangement drawing of 33/11 kV outdoor (AIS) medium voltage substations.

Table of Contents:

1. Factors affecting the layout and arrangement of substations
   1. Site selection and space constraints
   2. Voltage level
   3. Supply security and reliability
   4. Provisions for easy maintenance and future expansions
   5. Operation flexibility and protection arrangement
2. Specific design requirements of substation layout and arrangements
   1. Busbar layout alternatives in switchyard for 33/11 kV substations
   2. Estimation of required space
      1. Switchyard
      2. Control room layout
      3. The access road, Station supply, and illumination
   3. Civil design aspects
   4. Safety clearances

1. Factors affecting the layout and arrangement of substations

Each substation is different in terms of their arrangement and design parameters. First, we will briefly discuss multiple factors that affect the design and layout of a substation.

1.1 Site selection and space constraints

Designing a suitable substation layout is heavily affected by site selection. Power distribution substations are mostly installed near load centers. The land nearby urban load centers are expensive and hard to acquire.

The layout should make the most of available space by reducing the footprint and meeting all the requirements of future proof and ideal substation design.

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1.2 Voltage level

While drafting the layout and arrangement drawings, minimum clearances, and space requirement of switchyard, the orientation of incoming and outgoing feeders, size of control and panel rooms, size of an access road, etc., all are heavily reliant on the voltage level of the substation.

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1.3 Supply security and reliability

Ideally, for the substation to offer the ultimate power security and reliability level, all substation equipment needs to have redundancy. However, such an option is not practically applicable due to cost as well as space constraints.