POWER HOUSE

Description• For distributing the power efficiently, power house is there.• It houses transformers and busbars for paralleling out the power flow to step

down the voltage level to the distribution level. • It receives power from CESC at 6.6 KV.• The power house has two incoming feeders from CESC feeding power to the

HT busbar at 6.6 KV.• All the arrangements are placed indoor. • Power is then distributed to different areas at 6.6 KV through power cables

from HT busbar.• The power house reroutes the incoming power to different load centers from

HT busbar.

Continued…• The load centers have their step down transformer for stepping down the

voltage level to 415 V 3ph from 6.6KV 3 ph. • The HT busbar is sectionalized to two sections and they are coupled by a bus

coupler circuit breaker. • Incoming feeders as all the load center are connected in ring- mesh

connection for better reliability of power. • It has two transformers of 350 KVA each to supply its local loads. • The outgoing feeders from the LT busbar have their own breaker for fault

protection. • The breakers are all placed indoors and the electro-mechanical relays are

integrated to the breaker in a panel board .

TRANSFORMERS

PARAMETERS RATINGS

KVA 350

No load voltage 6/0.415KV

Amperes HT=33.68, LT= 468.9

Phases 3

Type of cooling ON

Frequency 50Hz

pu voltage drop 0.0486 V

Vector group Dy 11

Max temp. rise in oil 45oC

All the transformers installed are 3-ⱷ step down, 2-winding transformers and they are installed indoor.

CIRCUIT BREAKER1. Vacuum Circuit Breakers are installed.2. Earlier Oil Circuit Breakers were used.3. OCBs had some problems such as sludge formation & lack of mobility of the

moving contact, the dielectric strength of the oil is lesser than inert environment.

4. Due to its large size, it requires more floor space.5. Advantages of Vacuum Circuit Breaker includes is that, its size is compact,

requires less maintenance, no possibility of jamming of the moving contacts, high dielectric strength and faster rate of recovery of dielectric strength.

6. Thus it is installed in low power low voltage applications.7. VCBs are suitable for use with 6.6 KV system with lesser breaking capacity

and the current system is using them extensively.

RELAYS• Types of relays installed for transformer protection are:1. Over current relay2. Earth fault relay

• Types of relays installed for feeder protection are:1. Over current relay2. Earth fault relay3. Distance protection relay

Single-Line Diagram