Sub stations

The assembly of apparatus used to change some characteristic(voltage,a.c to dc,frequency ,p.f. etc..)of electric supply is called a substation.

Key points

1. It should be located at proper site2. It should provide safe and reliable arrangement3. It should be easily operated and maintained4. It should have minimum capital cost.

Classification of substations• According to service requirement transformer substation Switching substation Power factor correction substation Frequency changer substation Converting substation Industrial substation

• On the basis of operating voltage H V substation –voltage between11kv and 66kv EHV substation- voltage between132kv and 400kv UHV substation –voltage above 400kv

• On the basis of constuctional feature Indoor substation Outdoor substation Under ground substation Pole mounted substation

Block diagram of typical supply system indicating different transfermer substations

Pole mounted substation and its schematic connection

Distribution transfermer & substation

Under ground substation

Equipments in a transformer substation

• Bus bars• Insulators• Isolator• Circuit breaker• Power transformer• Instument transformers• Metering and indicating instruments• Miscellaneous euipment ( fuses ,carrier –current

equipment)

Instrument transformers

USE OF ISOLATORS IN SUBSTATIONS

SINGLE BUS BAR ARRANGMENT IN SUBSTATION

SINGLE BUSBAR WITH SECTIONALISATION

DUPLICATE BUSBAR SYSTEM

TERMINAL SUBSTATION

THROUGH SUBSTATION

KEY DIAGRAM OF 66/11 KV SUBSTATION

KEY DIAGRAM OF 11KV/400V SUBSTATION

Neutral grounding

Enclosure connected to neutral wire

Ground wire connected to enclosure

System grounding