SF6 Breakers

20 H	The breaker uses SF6 (Sulpher Hexa fluoride) gas for arc extinction purpose. This gas has excellent current interrupting and insulating properties, chemically, it is one of the most stable compound in the pure state and under normal condition it is physically inert, non-flammable, non toxic and odourless and there is no danger te personnel and fire hazard. It's density is about. 5 times that of air insulating strength is about 2-3 times that of air and exceeds that of oil at 3 Kg/Cm pressure. SF6 breaker called as maintenance free breaker, has simple construction with few moving parts: The fission products created during breaking and not fully recombined are, either precipitated as metallic fluoride or absorbed by a static filter which also absorbs the residual moisture. Since no gas is exhausted from the breaker and very little compressed air is required for operation, noise during the operation is also very Jess. Since SF6 gas is inert and stable at normal temperature, contacts do not sutler from oxidization or other chemical reactions, whereas in air or oil type breakers oxidation of contacts would cause high temperature rise.. SF6 gas circuit breakers„.designed to conform to the same standards as air or oil breakers, but in operation it is possible to get better service even at higher fault levels.

20 H-01 D	Gas Pressure: Record pressure on pressure gauge and temperature. It should be within limits as prescribed by manufacturer.
20 H-02 D	Air Pressure : Measure the air pressure it should be within specified limits. If not check whether the discrepancy is due to a pressure gauge or leakage through joints, attend the same.
20 H-03 D	General Cleanliness : Check the cubicle, clean the same by vacuum pump, if necessary.
20 H-04 D	Compressor: Drain water from the air reservoir, if any.

20 H0-5 Q	Heaters: Check that heaters are working properly. Attend/Replace heaters if found defective.
20 H-06 Q	Compressor: Check the level of oil in compressor. Add oil if necessary.
20 H-07 Q	SF6 Gas in Pole: Check the gas density through the meter provided in the cubical in case any difference attend the same.

20 H-08 Y	Check the porcelain for any damage.
20 H-09 Y	Check the grounding pad for looseness.
20 H-10 Y	Check the foundation bolts for looseness.
20 H-11 Y	Check the compressor for normal operation.
20 H-12 Y	Check the joints of pipe line for any leakage.
20 H-13 Y	Check that all valves are in working order.
20 H-14 Y	Check the position of indicator.
20 H-15 Y	Check the rust in mechanical linkage and their looseness.
20 H-16 Y	Lubricate all mechanism.
20 H-17 Y	Check the control wiring for looseness and tighten the loose connection, if any.
20 H-18 Y	Check the contacts of the auxiliary switch.
20 H-19 Y	Measure contact resistance in close position and compare with Firm's Test Results
20 H-20 Y	Check the tripping and closing at 50% of DC Voltage.
20 H-21 Y	Check the terminal connectors.