Both the gas relay and the Buchholz relay are examples of the protective relays that may be found in transformers. However, these two types of relays have very different purposes and modes of operation.
In a transformer’s oil conservator tank, the oil level and pressure are monitored with the use of a device called a gas relay, which is also known as an oil conservator relay or an oil level relay.
In order for the gas relay to function, it must first identify changes in the pressure of the gas contained inside the tank. These changes are brought on by the temperature-induced expansion and contraction of the transformer oil.
It is possible that the transformer has a problem or a leak if the gas pressure is higher than a specific threshold; in this condition, the gas relay will trip to avoid damage to the transformer.
On the other end, a Buchholz relay is utilised to find faults in the oil-immersed winding or core of the transformer and then to isolate them. During operation, it sends a signal to trip the transformer if it detects the presence of gas or oil vapour that was caused by a problem, such as a short circuit or a breakdown in the insulation.
When gas or oil vapour is found, the Buchholz relay will send out an alarm signal. This is a supplementary purpose that the relay has, and it indicates that there may be a problem that needs to be looked into. In conclusion, while both relays are employed in transformers for the purpose of providing protection, the gas relay is utilised to monitor the oil level and pressure inside the conservator tank, the Buchholz relay is utilised to identify and isolate problems within the transformer’s winding or core. Both relays are utilised in the same method.