Principle of vacuum tester
Power Technology Show
The vacuum switch vacuum tester is measured by a magnetron discharge method. Pulling the two contacts of the vacuum interrupter to a certain distance, applying an electric field pulse high voltage, placing the arc extinguishing chamber in the solenoid coil or placing the new electromagnetic coil on the outdoor side of the arc extinguishing, and applying a large current to the coil Thereby generating a pulsed magnetic field synchronized with the high voltage in the arc extinguishing chamber. Thus, under the action of the strong magnetic field and the strong electric field, the charged ions in the arc extinguishing chamber spirally move and collide with the residual gas molecules, and the generated ion current is approximately proportional to the residual gas density, that is, the vacuum degree. For different vacuum tube models （tube types）, due to their different structures, the ion currents are different under the same contact opening distance, equivalent vacuum, and equivalent electric and magnetic fields. Through the experiment, the corresponding relationship between the vacuum degree and the ion current of various tube types can be calibrated. When the ion current is measured, the vacuum degree of the tube type can be obtained by querying the ion current-vacuum curve of the tube type.
In order to improve the test sensitivity of the conventional magnetron discharge test in order to improve the test sensitivity, it is necessary to remove the arc extinguishing chamber from the circuit breaker and place it in the solenoid line pipe. In this way, the arc extinguishing chamber needs to adjust the mechanical parameters when reinstalling the circuit breaker, and the workload is large and requires a professional. The new magnetron coil can be used to surround the arc extinguishing chamber from the side, so that it is not necessary to disassemble the arc extinguishing chamber. The single-chip microcomputer is used for synchronous control and data acquisition processing, which improves the field test sensitivity of the vacuum chamber of the arc extinguishing chamber.
The whole machine is composed of a measurement control circuit, an electric field high voltage generating circuit, a field coil current control circuit, a communication, a printer, a liquid crystal display circuit and the like. The working process is: the measurement control circuit issues a command, the switching power supply charges the magnetic field capacitor, and is monitored by the control circuit. When the voltage on the magnetic field capacitor reaches a predetermined value, the control circuit sends two control signals to respectively control the output of the electric field high voltage and When the field coil current is turned on, the arc extinguishing chamber is in a state of strong electric field and strong magnetic field, and the arc extinguishing chamber starts to discharge, generating an ion current I, as shown by a curve I in FIG. The current is input to the single-chip microcomputer through the sampling resistor R and the pre-processing circuit, and finally the measured vacuum value is displayed by the liquid crystal display.