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First of all, let's understand the basic principle of calibrator of SF6 gas density relay. SF6 gas in SF6 high voltage circuit breaker is sealed in a fixed container. Under the rated pressure of 20℃, it has a certain density value, which is within the range of various allowable conditions for circuit breaker operation. Although the pressure of SF6 gas varies with temperature, the density value of SF6 gas remains constant. Because the insulation characteristics and arc extinguishing performance of SF6 circuit breaker largely depend on the density of SF6 gas, the monitoring of SF6 density is particularly important. In order to achieve the purpose of frequent density monitoring, the national standard stipulates that SF6 circuit breaker should be equipped with SF6 relay. Density relay plays a role of control and protection, so it is particularly important to use the calibrator of SF6 gas density relay to calibrate the density relay regularly.
SF6 relay calibrator mainly measures four parameters for density relay calibration. The testing process of these four parameters is as follows.
Under the ambient temperature, when SF6 relay is at zero pressure, the SF6 relay is charged slowly at a certain speed. When the latching relay of SF6 relay operates, the pressure value under the current ambient temperature is recorded and converted into the equivalent pressure value at 20℃, which is the latching recovery value of SF6 relay.
Continue to charge SF6 relay slowly at a certain speed. When the alarm relay of density relay operates, record the pressure value under the current ambient temperature and convert it into the equivalent pressure value at 20℃, which is the alarm recovery value of SF6 relay.
Under the ambient temperature, when the pressure in SF6 relay is greater than the alarm recovery value, the gas is slowly deflated at a certain speed. When the alarm relay of SF6 relay operates, the pressure value under the current ambient temperature is recorded and converted into the equivalent pressure value at 20℃. The equivalent pressure value at 20℃ is the alarm value of SF6 relay.
Continue to slowly deflate the SF6 relay at a certain speed. When the latching relay of SF6 relay operates, record the pressure value under the current ambient temperature and convert it into the equivalent pressure value at 20℃, which is the latching value of SF6 relay.
A high-quality calibrator of SF6 gas density relay should have the above four technical indicators featuring efficient and stable testing, good repeatability, cheap and fine.
