Field Test Method for Vacuum Switch Vacuum Degree Tester

With the application of vacuum switch, it is very important to detect the vacuum degree of vacuum switch regularly or irregularly. The traditional detection method is "withstand voltage method", that is, when the vacuum switch is in the off state, a certain voltage is applied between the static and static contacts to detect the size of the leakage current, so as to infer the quality of the vacuum tube. The advantage of this method is that it is simple to operate, and the disadvantage is that it can only qualitatively detect the quality of the vacuum tube, and the vacuum degree can not be accurately distinguished between 1010Pa, so it is impossible to judge the development trend of the leak "that is, how much leakage is the same vacuum switch compared with the last time".

The vacuum degree tester is measured by magnetic control discharge method. The two contacts of the vacuum switch arc extinguishing chamber are separated by a certain distance, the electric field pulse high voltage is applied, the arc extinguishing chamber is placed in the solenoid ring or the new electromagnetic coil is placed outside the arc extinguishing chamber, and a large current is applied to the coil, so as to generate a pulsed magnetic field synchronized with the high voltage in the arc extinguishing chamber. In this way, under the action of pulsed strong magnetic field and strong electric field, the charged ions in the interruptor move helically and are ionized by collision with the residual gas molecules, and the ionic current generated is approximately proportional to the density of the residual gas, that is, the vacuum degree. For different vacuum tube types (tube types), due to their different structures, under the conditions of the same contact opening distance, the same vacuum degree, and the same electric and magnetic field, the size of the ion current is also different. The corresponding curves of vacuum degree and ion current of various tube types can be calibrated by experiments. When the ion current is measured, the vacuum degree of the tube can be obtained by querying the ion current-vacuum degree curve of the tube.

In order to improve the test sensitivity, it is necessary to remove the interrupter from the circuit breaker and place it in the spiral pipeline when the vacuum degree of the interrupter is tested by conventional magnetic control discharge. In this way, the arc extinguishing chamber needs to adjust the mechanical parameters when the circuit breaker is installed again, which requires a large workload and professional personnel. With the new magnetron coil, the interrupter chamber can be surrounded from the side, so that the interrupter chamber does not have to be disassembled. The single chip microcomputer is used for synchronous control and data acquisition and processing, which improves the sensitivity of the field test of the vacuum degree of the interrupter.

Vacuum degree tester use method

1. Power off both ends of the vacuum tube under test. The vacuum tube to be measured does not need to be removed from the switch cabinet, but the vacuum tube must be in a normal disconnected state, and open the vacuum switch in and out of the tool brake; If the vacuum switch is not installed, it is also necessary to take measures to make the static and static contacts of the vacuum switch in a normal open distance state, and place them on a well-insulated support frame. At the same time, pay attention to the installation position of the magnetic coil, which should be installed in the middle of the arc interrupter.

2. Connect the vacuum tube to the instrument. The specific operation is as follows: first connect the ground end of the vacuum degree tester to the earth, then connect the magnetron coil to the positive and negative ends of the magnetic field voltage of the instrument through the magnetic field current line, connect the high voltage output end to the static contact of the vacuum tube with a high voltage cable, and connect the ion current input end to the moving contact of the vacuum tube through the ion current line (shielding line).

3, after the measurement, turn off the instrument power, and wait 5 seconds before disconnecting. When removing the cable, remove the test cable connected to the instrument, and then remove the cable connected to the vacuum tube and magnetic coil.

Vacuum degree tester operation precautions

The vacuum tester enclosure should be reliably grounded

In order to improve the measurement accuracy, the outer surface of the vacuum switch should be wiped clean before the test;

Select the correct tube type of the vacuum tube

During the test, the high voltage output end will output about 20KV high voltage, please keep the insulation distance from the human body and the low voltage wire end (it is recommended to keep a distance of more than 0.5 meters from the human body), the magnetic field voltage output end output about 1600V high voltage, please pay attention to safety.

When the vacuum degree tester is tested, the connection should first connect the magnetic coil and the vacuum tube, and then connect to the instrument. After the test is completed, the test cable connected to the instrument should be removed first, and then the cable connected to the magnetron coil and vacuum tube should be removed. If you forget to connect the magnetron coil and press the measurement key directly during use, the power supply should be turned off immediately and the magnetron coil should be connected again. Please note that there will be a high voltage at the output end of the magnetic field voltage at this time. To avoid being damaged by the residual voltage on the capacitor.
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