This document discusses the design and automation of electrical sub-stations, which are critical for maintaining a reliable power supply. Key considerations for sub-station layout include location, safety, reliability, ease of operation, and cost. It also classifies sub-stations based on service requirements and construction features, detailing various types and necessary equipment.

1. P O W E R S TAT I O N P R A C T I C E
( E E 3 0 7 )
SUB-STATION DESIGN AND
AUTOMATION (UNIT 3)

2. INTRODUCTION
• The assembly of apparatus used to change some characteristic
(e.g. voltage, a.c. to d.c., frequency, p.f. etc.) of electric supply
is called a sub-station.
• Sub-stations are important part of power system. The
continuity of supply depends to a considerable extent upon the
successful operation of sub-stations. It is, therefore, essential
to exercise utmost care while designing and building a sub-
station.

3. INTRODUCTION
• The following are the important points which must be kept in view
while laying out a sub-station :
• (i) It should be located at a proper site. As far as possible, it should
be located at the centre of gravity of load.
• (ii) 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.
• (iii) It should be easily operated and maintained.
• (iv) It should involve minimum capital cost

4. CLASSIFICATION OF SUB-STATIONS
• According to service requirement.:
• Transformer sub-stations
• Switching sub-stations.
• Power factor correction sub-stations.
• Frequency changer sub-stations
• Converting sub-stations
• Industrial sub-stations

5. CLASSIFICATION OF SUB-STATIONS
• According to constructional features.:
• Indoor sub-station
• Outdoor sub-station
• Underground sub-station
• Pole-mounted sub-station

6. COMPARISON BETWEEN OUTDOOR AND
INDOOR SUB-STATIONS

7. TRANSFORMER SUB-STATIONS
• (i) Step-up sub-station
• (ii) Primary grid sub-station
• (iii) Secondary sub-station
• (iv) Distribution sub-station

8. TRANSFORMER SUB-STATIONS

9. POLE-MOUNTED SUB-STATION

10. UNDERGROUND SUB-STATION

11. SYMBOLS FOR EQUIPMENT IN SUB-
STATIONS

12. SYMBOLS FOR EQUIPMENT IN SUB-
STATIONS

13. EQUIPMENT IN A TRANSFORMER SUB-
STATION
• Bus-bars
• Insulators
• Isolating switches
• Circuit breaker
• Power Transformers
• Instrument transformers
• Metering and Indicating Instruments

14. BUS-BAR ARRANGEMENTS IN SUB-
STATIONS
• Single bus-bar system

15. BUS-BAR ARRANGEMENTS IN SUB-
STATIONS
• Single bus-bar system with sectionalisation

16. BUS-BAR ARRANGEMENTS IN SUB-
STATIONS
• Duplicate bus-bar system.