STANI MEMORIAL COLLEGE OF ENGINEERING & TECHNOLOGY

POWER SYSTEM DESIGN LAB

EXPERIMENT NO. 2

Aim: - Auxiliary power supply scheme for thermal power plant.

Apparatus Requirements: - Thermal Power Plant, Main Power Supply, Auxiliary Power

Supply.

Theory: - The auxiliary power supply can be divided into two categories: Urgent Auxiliary Supply

and Service Auxiliary Supply.

The Urgent Auxiliaries are those which are associated with the running of a unit and whose loss

would cause an immediate reduction of the unit output.

The Service Auxiliaries are those whose loss would not affected the output until after a considerable

time.

Circuit Diagram:-

Precautions:-

1) Do not touch any live conductor.

2) Please keep distance from electrical equipments because voltage level very high i.e. 132 kV,

220 kV, and 400 kV.

Procedure:-

1) There should be two main sources of supply (I) from the grid via the station transformers, (II)

from the main generators via the unit transformers.

2) The urgent auxiliaries should be supplied from the unit transforms and the service auxiliaries

from the station transformers. Each generating unit should have a separate supply and the

failure of one unit should not affect the other.

3) The unit board and the station board should be interconnected for starting purposes and to

provide a supply in case the unit supply fails.

4) A standby supply should also be provided so that a unit can be brought back to service rapidly

in the event of a failure of one of the components in any of the normal supply circuits.

Observation Table:-

Calculation:-

Result:- We have successfully studied about Auxiliary power supply scheme of thermal power

plant.

Viva- Voice

Ques. 1 How many categories are divided of auxiliary power supply?

Ques. 2 For which supply loss would cause an immediate reduction of the unit output?

Ques. 3 What is Thermal Power Plant?

Ans 1. Urgent Auxiliary Supply

Ans 2. The auxiliary power supply can be divided into two categories: Urgent Auxiliary Supply and

Service Auxiliary Supply.

Ans 3. A thermal power station is a power plant in which the prime mover is steam driven. Water is

heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes

through the turbine, the steam is condensed in a condenser and recycled to where it was heated.