In power distribution network operation, pole-mounted circuit breakers are core equipment for line protection. For the large number of SF6 pole-mounted circuit breakers in operation, maintaining the gas insulation performance directly determines the breaking capacity and service life of the equipment. One crucial step that cannot be overlooked is that on-site maintenance personnel need to check whether the air pressure value of Lv Pole Mounted Circuit Breakers is normal. This seemingly simple reading is actually a vital window into the health status of the equipment.

Why is the gas pressure parameter the "lifeline" of equipment operation?

The medium basis for insulation and arc extinguishing

The SF6 gas filling the inside of low-voltage pole-mounted circuit breakers possesses excellent insulation and arc-extinguishing characteristics. When the circuit breaker interrupts load current or fault current, the arc is rapidly cooled and extinguished in the gas medium. Maintaining the gas pressure within the rated range is essential to ensure the effective operation of this arc-extinguishing capability.

Potential risks of low-pressure operation

During long-term operation or due to environmental influences, slow gas leakage may occur. When the gas pressure drops below a critical value, the insulation strength of the medium will decrease significantly. When a line is struck by lightning or experiences a short circuit, the circuit breaker may fail to open normally, potentially leading to equipment explosion or power grid accidents. Some circuit breakers are equipped with a low-pressure interlock device, which automatically locks the operating mechanism when the pressure is too low to prevent tripping due to a fault.

Key Points for Pressure Check During On-Site Inspections

Standardized Reading and Recording

Inspection personnel must use a dedicated pressure gauge to read the indicated value. When reading, ensure the gauge is within its calibration period and observe whether the pointer is stable. Record the reading and compare it with the rated pressure value on the equipment nameplate.

Adjustment Based on Ambient Temperature

Pressure values ​​are affected by ambient temperature. Refer to the pressure-temperature characteristic curve of this type of low-pressure pole-mounted circuit breaker to convert the on-site reading to the corresponding value at the standard temperature. This adjustment is particularly important during periods of rapid temperature change, helping to distinguish between normal physical changes and actual leaks.

Auxiliary Observation of Leakage Signs

In addition to directly reading the pressure gauge, observing the equipment body and connecting pipes for traces of oil, dust accumulation, or other contaminants can also help determine the sealing condition. Based on historical inspection records, if the air pressure value shows a continuous downward trend, leak detection or planned maintenance should be arranged.