PTTI Portable Fault Gas Detector

The Portable Fault Gas Detector provides a sensitive and effective means for detecting faults in electrical transformers having gas space above the insulating oil. It makes available an important means to improve the continuity of electrical service. Gas samples can be taken without de-energizing or disturbing the operation of the transformer in any way.

The Portable Fault Gas Detector employs the heat of combustion of flammable gases to measure the quantity of these in the gas sample. The measuring filaments consist of two small separately housed platinum coils heated by an electrical current. A mixture of the sample flammable gas and air is brought into contact with one of the coils, allowing a rapid catalytic combustion to take place at the surface of the filament. This burning of the combustible gas increases the temperature of the filament, causing a proportional change in its resistance. The second filament is heated in a neutral atmosphere of air and serves as a reference or standard. While it responds to any combustible gas, it has been calibrated to indicate very closely the total percentage of combustible gases in a transformer gas space produced by fault conditions.

The Portable Fault Gas Detector may be used in the field or in the laboratory. In the field, it is connected directly to the transformer gas space. In the laboratory, sampling cylinders supply gas samples taken from transformers in the field.