Necessity and basic principle of automatic calibrator of SF6 relay

1. The necessity of calibrating the SF6 relay

SF6 switch is a high voltage electrical appliance widely used in power system. The reliable operation of the SF6 switch has become one of the most concerned issues of the power supply department.

The SF6 gas density relay is an important component used to monitor the change of the SF6 gas density in the SF6 switch body during operation. Its performance directly affects the operational safety of the SF6 switch.

The SF6 gas density relays on-site do not operate frequently. After a period of time, there will be some phenomena such as inflexible action and poor contact of contact. Some of the density relays have poor temperature compensation performance. When the ambient temperature changes suddenly, the SF6 relay may even malfunction.

Therefore, DL/T596-1996 "Preventive Test Regulations for Power Equipment" stipulates: Each user unit of SF6 switch should periodically check the SF6 gas density relay. From the actual operating conditions, it is also very necessary to periodically verify the SF6 relays and pressure gauges in field operation.

2. The basic principle of SF6 relay calibration

The gas pressure in a closed container changes with the temperature. In order to facilitate statistics and comparison, the relative pressure value of SF6 at 20°C is usually taken as the standard value. During the on-site calibration, the SF6 pressure value measured at a certain ambient temperature must be converted to its equivalent pressure value at 20°C, so as to judge the performance of the SF6 relay.

Calibration of blocking recovery value: when the SF6 relay is at zero pressure under ambient temperature, slowly inflate the SF6 relay at a certain speed. When the block relay of the SF6 relay is activated, the pressure value under the current ambient temperature is recorded and is converted to the equivalent pressure value at 20°C. The equivalent pressure value at 20°C is the blocking recovery value of the SF6 relay.

Calibration of alarm reply value: continue to slowly inflate the SF6 relay at a certain speed. When the alarm relay of the density relay is activated, the pressure value under the current ambient temperature is recorded and converted into the equivalent pressure value at 20°C. The equivalent pressure value at 20°C is the alarm response value of the SF6 relay.

Calibration of alarm value: under ambient temperature, when the pressure in the SF6 relay is greater than the alarm response value, exhaust slowly at a certain speed. When the alarm relay of the SF6 relay is activated, the pressure value at the current ambient temperature is recorded and converted to the equivalent pressure value at 20°C. The equivalent pressure value at 20°C is the alarm value of the SF6 gas density.

Calibration of blocking value: continue to slowly deflate the SF6 relay at a certain speed. When the block relay of the SF6 relay is activated, the pressure value at the current ambient temperature is recorded and converted into the equivalent pressure value at 20°C. The equivalent pressure value at 20°C is the blocking value of the SF6 relay.

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