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TRANSFORMER COMPONENTS AND MAINTENANCE
4.22 CHAPTER FOUR
GAS RELAY AND COLLECTION SYSTEMS
Introduction
Most utilities and large industries have a gas relay mounted on their power transformers.
As mentioned earlier, gases are generated by the chemical and electrical phenomena asso-
ciated with the development of faults in oil-filled transformers. A significant amount of gas
is normally formed in the early stage of the fault.
The gases generated and the air expelled from the oil by the fault rise to the top of the
equipment and get collected in a gas relay. Figure 4.13 illustrates a gas collection system. It
ensures that gases trapped in various pockets are allowed to escape and travel to the gas relay.
Gas Relay
The gas detector relay (Fig. 4.14) gives an early indication of faults in oil-filled transformers.
There are two types of faults:
1. Minor faults that result in a slow evolution of gases. These faults may result from the
following:
● Local heating
● Defective insulation structures
FIGURE 4.13 Gas relay and gas collection systems.
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