Judgment of Test Methods and Test Results of SF6 Gas Density Relay

SF6 relay is an important protection and control element in the power system. If the circuit breaker fails, it will cause great economic losses. To ensure the reliability of the circuit breaker operation, it is necessary to constantly monitor the indicators of the circuit breaker, especially SF6 gas, which must meet the provisions of the relevant standards, so that SF6 circuit breaker can be in good working condition for a long time. It is very important to supervise and calibrate the alarm and locking action values of the newly installed SF6 gas density relay and the SF6 gas relay in operation to ensure the normal operation of electrical equipment.

1. Test method of SF6 relay

Calibrate SF6 relay. The calibrator can be used to check sulfur hexafluoride density relay and pressure gauge.

2. Test steps of SF6 relay

(1) Cut off the gas circuit of density relay of the tested equipment from the gas circuit of the equipment body.

(2) Cut off the power supply of the density relay control loop of the equipment under test.

(3) Connect the gas connection part of the density relay calibrator to the gas circuit of the density relay under test.

(4) Connect the node socket of density relay calibrator to the corresponding node of the density relay under test.

(5) Adjust the pressure of the storage cylinder of density relay calibrator so that it reaches the alarm or closing pressure of the density relay under test.

(6) Record the action value and return value of the density relay to reach the alarm or closing (the recorded value should be corrected to the pressure value at 20℃).

(7) For the simultaneous installation of pressure gauge equipment, calibrate the action value and return value of the alarm or closing, and you can record the pressure gauge at the same time, and compare it with the pressure value given by SF6 relay calibrator (in addition, 2 to 4 points of different pressure values can be corrected as needed). The calibration of each pressure gauge should be 5 to 8 points.

(8) The calibration of density relay that has not been installed is carried out according to the items 3 to 6.

3. Test results judgment of SF6 relay

The calibration results of the gas density relay are compared with the setting values and allowable error ranges of the alarm and closing nodes of the density relay by the manufacturer. For the calibration of the pressure gauge, only the indicated values of the pressure gauge and the pressure values given by the corresponding density relay calibrator are given.

4. Matters need attention about the calibration of SF6 relay

(1) During calibration, the connection position of the contact socket of the calibration platform of the density relay should be correctly selected, and the connection to the normally open or normally closed contact of the gas density calibrator relay should be avoided.

(2) The pressure and temperature of the density relay calibrator shall be verified by the metrology verification department. The verification period shall be the same as the national verification period of pressure and temperature gauges.

(3) If the test result of this operation does not conform to the factory value, the test shall be reviewed. When nonconformance is confirmed, it shall be disposed of by the user of sulfur hexafluoride electrical equipment as required.

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