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SF6 density calibration and automatic inflation and deflation device is mainly composed of standard calibration SF6 relay, connecting stainless steel valve (including exhaust valve, stop valve, inflation valve, body connecting valve, etc.), connecting hose, and automatic inflation and deflation control unit. It is a precision instrument with integrated measurement and display functions, fast response and small hysteresis.
1. Introduction of the calibration function
The SF6 density calibration and automatic inflation and deflation device have the function of not disassembling and calibrating SF6 relay. Even with the connection valve that does not meet the requirement of disassembling and calibrating on-site, the SF6 relay in the air chamber can still be calibrated without disassembling and the real pressure measurement can be realized.
2. SF6 density calibration strategy
(1) It does not meet the requirements of non-disassembly testing
Step: Close the exhaust valve and inflation valve, open the globe valve, connect the body calibration valve connector, then you can get the real pressure of the air chamber and calibrate the density relay reading.
(2) The main part meets the requirement of non-disassembly calibration
Step: Close the exhaust valve and inflation valve, close the body block valve, open the stop valve, connect the body connector, open the block valve, then you can get the real pressure in the calibration gas chamber. Keep the body block valve closed, by controlling the air source and the inflation and deflation valve, then you can calibrate the original density relay, covering its range ability.
The traditional artificial inflation method cannot make the pressure reach the rating value, and there is a certain error. SF6 relay calibration and automatic inflation and deflation device can manually set the rating value and automatically stop when reaching the rating value, completely eliminate the error generated during inflation, and improve the operation reliability of the equipment.
1. Principle introduction
The control loop of the automatic inflation and deflation device is mainly composed of an air switch, contactor, button indicator light, solenoid valve, digital display pressure gauge, etc. Among them, the digital display pressure gauge is the standard parent gauge, its accuracy is as high as 0.5%, and the pressure can be arbitrarily adjusted between 0 to 1 MPa. The digital pressure gauge has two pairs of bi-directional control contacts for low-pressure alarm, high-pressure disconnection and low-pressure disconnection and high-pressure alarm, so as to realize the control of the solenoid valve on/off and contactor suction respectively.
Take the inflation process as an example. When the inflation start button is pressed, the normally open contact of the inflation contactor is closed so that the normally closed inflation solenoid valve is opened. At this time, the air source pressure is higher than the pressure of the air chamber, and inflation can be carried out. When the gas chamber pressure reaches the preset value, the digital pressure gauge control contact makes the normally closed contact become normally open, the inflation contactor coil loses power, the electromagnetic valve state changes, the inflation stops, and the automatic inflation function is realized. The same goes for the deflation process. In case of an emergency, it can be stopped immediately by the emergency stop button.
2. Inflation and deflation strategy
When the pressure of GIS gas chamber decreases or rises, it needs to be inflated and deflated. The specific steps are as follows: Open the air source and operate the power circuit breaker; Set inflation and deflation low-pressure alarm, high-pressure disconnection and low-pressure disconnection, high-pressure alarm values; Start inflation and deflating button, observe the indicator; Compare the set value and the actual pressure of digital pressure gauge; The contactor action makes the normally closed solenoid valve open and begins to inflate or deflate; Reach the set value when the contactor action, so that the solenoid valve loses power and is closed; Turn off the operating power and air source; The process is complete.
1. Carry out the calibration work of the SF6 relay without power failure or disassembly, with high accuracy and reliability of the instrument, which can timely and quickly discover possible hidden dangers.
2. The production cost is low, the automatic inflation and deflation operation is realized, the error is completely eliminated, so that the accurate operation at the rated pressure can be ensured, improving the service life of the equipment and the operation reliability of the equipment.
3. The target value in the range of 0 to 1 MPa can be preset for the inflation and deflation operation, which has strong practicability, wide application range, high accuracy and overall practicability.
