Buchholz relay is a protective device used for oil-filled transformers. It is designed to detect the faults occurring inside the transformer and to trip the circuit breaker to prevent further damage. The correct location for Buchholz relay is option 'C', which is connected in the pipe connecting main tank of transformer and conservator.

Explanation:

The Buchholz relay is installed in the oil transfer pipe connecting the main tank of the transformer to the conservator tank. The relay is placed in this location because it can detect the faults that occur in the transformer.

The conservator tank is used to store the oil that is used to cool the transformer. The oil expands and contracts as the temperature changes. The Buchholz relay detects the change in oil level and operates when the oil level drops below a certain point.

The Buchholz relay is connected to two float switches that are located in the conservator tank. The float switches are designed to detect changes in oil level and send a signal to the relay. If there is a fault that occurs in the transformer, such as a short circuit or an overloading, the oil will heat up and expand. This will cause an increase in pressure in the oil transfer pipe.

The increase in pressure will cause the oil to flow through the Buchholz relay, which will detect the change in pressure and send a signal to the circuit breaker. The circuit breaker will trip and disconnect the transformer from the power supply to prevent further damage.

In conclusion, the Buchholz relay is an important protective device for oil-filled transformers. It is installed in the oil transfer pipe connecting the main tank of the transformer to the conservator tank. Its location allows it to detect the faults that occur in the transformer and prevent further damage.

Bucholz relay is used to protect the oil transformers