Buchholz Relays are mounted on transformers. But, the relays are always at a good height so that regular monitoring of gases is not easy. Gas Collecting device is a bottle like device that is mounted at a approachable height and connected to a Buchholz through a pipe. During gas accumulation in Buchholz the gas travels automatically into the GCD through the pipe. Here the gas can be detected for probable fault by its colour or taken out for DGA.
The construction of GCD is very simple. A glass container has a casted bottom and top lid. 2 Nos. Needle valves have been provided that open into the container. A third needle valve at side may be present. This valve is used when there is requirement to provide draining pipe from bottom of Buchholz. The bottom needle valve acts as a entry port for the pipe connecting the highest air release valve of Buchholz. During commissioning and functioning the valve at top of Buchholz and entry valve on GCD always remain open. The top needle valve of GCD is used to release the air so that the oil pipe line and GCD container get flooded with oil and no air exist there.
Detection of electrical fault by its colour and easy availability for DGA are the main advantages of this device.
For connection of GCD with Buchholz copper piping or flexible Stainless Steel Hose can be used. As there may be variation in the threads on air release valve of Buchholz it is advised to use suitable adopter for take-off.
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