Hello friends, today I will tell you that What is indoor sub-station? And what is outdoor sub-station?: If you also want to know, keep reading this article thoroughly.
What is indoor sub-station?
In these electrical sub-stations, equipment like transformers and switchgear are installed inside the building. These are generally made of capacity up to 117 and 250 kVA. Still, where impurities (conducting dust, smoke, metallic corrosive gases) are found in the surrounding environment, the sub-stations are made of 33kV and 66kV.
The switchgear at the supply or primary side only houses the circuit breaker. High voltage is supplied to the primary side of the transformer with the help of a circuit breaker. The feeders are connected to the bus bar. The isolating switch and circuit breaker are installed in the feeder panel. The main reason for installing an indoor substation is that the possibility of fire can be reduced by installing a fire-resistant wall and fire extinguishers. Carbon dioxide is mainly used to extinguish fires. The layout of the indoor type sub-station is shown in Fig. (1).
This type of sub-station consists of two transformers of about 500 kVA each. Generally, the primary voltage is 11 kV, and the secondary voltage is 400/230V. The supply is supplied to the primary side of the transformer, and the secondary side is connected to the low-voltage bus bar. Feeders are connected to multiple consumers of electricity or distribution systems of a specific area. In some selected areas, a panel consisting of high rating circuit breaker and isolator is provided with an ammeter in each phase (for 3 phases, three ammeters), a voltmeter with selector switch, an A wattmeter, a power multiplier meter, and an energy meter is attached, and a reverse power relay is used for protection. Several safety devices are employed to protect the feeder. A merge-price protection device with an earth leakage relay is used to protect the transformer. To protect the transformer, it is necessary to have a Bakholz relay in it.
- Read more: what is a single-phase transformer
The sub-station must have batteries, fire fighting equipment, and emergency lights, etc.
The following are the accessories of an indoor-type sub-station
(j) storage battery
(ii) fire fighting equipment
A battery room is installed in the sub-station. Sometimes the battery is used as an emergency light due to the non-availability of electricity in the sub-station. Hence the battery is helpful for the following reasons.
(a) As an emergency light in case of supply failure.
(b) Required in the operation of switch operating solenoid and protective gear.
Indoor type substations have several subdivisions, including control subdivision, protection subdivision, main bus-bar subdivision, circuit breaker, operating mechanism subdivision, and current-transformer and cable-seal box subdivision. Figure 2. Is.
What is outdoor substation?
Outdoor substations are generally more suitable for primary and secondary transmission. Its structure depends on the supply voltage, the capacity of the transformer, the cooling method of the transformer, switchgear, and protection gear.
Outdoor substations are designed for very high voltages, so their equipment is also of a higher rating. Outdoor substations are designed for 33 kV to 440 kV. The equipment used at an outdoor substation also depends on the substation’s capacity, voltage, type, and switchgear design. The outdoor sub-station is illustrated in Figure 3.
- Read more: what is filter circuit?
now you know that What is indoor sub-station? And what is outdoor sub-station.