The common method for a vacuum degree tester to judge whether the vacuum tube of an empty circuit breaker has deteriorated is the power frequency withstand voltage method, which can only judge the arc extinguishing chamber with severely deteriorated vacuum degree. When the vacuum degree deteriorates to 10-2～10-1 Pa, although the breakdown voltage has not decreased, the arc extinguishing chamber is already unqualified. This vacuum degree tester uses an excitation coil and applies the magnetic control discharge method to test the vacuum degree of the arc extinguishing chamber without disassembling it. At the same time, a microcomputer is used for synchronous control and data acquisition processing, making the on-site testing sensitivity of the arc extinguishing chamber vacuum degree reach 10-5Pa.

    The outstanding feature of this vacuum switch vacuum degree tester is the adoption of a new type of excitation coil and data processing method, achieving non-disassembly measurement of vacuum degree. This instrument has the advantages of convenient use, simple operation, and non-disassembly measurement. It is a practical detection instrument widely applicable to departments that use vacuum switches, such as electric power, steel, railway, coal, and textile industries.

 The vacuum degree tester separates the two contacts of the arc extinguishing chamber by a certain opening distance and applies pulse high voltage; places the arc extinguishing chamber inside a spiral coil or places a new type of electromagnetic coil outside the arc extinguishing chamber, and applies a magnetic field voltage to the coil, thereby generating a pulse magnetic field synchronized with the high voltage inside the arc extinguishing chamber. Under the action of the pulse magnetic field and strong electric field, electrons in the arc extinguishing chamber move in a spiral motion and collide with residual gas molecules to cause ionization. The resulting ion current is proportional to the density of residual gas (i.e., the vacuum degree value). For different types of vacuum tubes (tube types), due to their different structures, under the same contact opening distance, same vacuum degree, and same electric and magnetic field conditions, the magnitude of the ion current is also different. Through experiments, the corresponding relationship curves between vacuum degree and ion current for various tube types can be calibrated. After measuring the ion current, the vacuum degree of the tube type can be obtained by querying the ion current-vacuum degree curve for that tube type.

    In the conventional magnetic control discharge method for testing the vacuum degree of the arc extinguishing chamber, in order to improve testing sensitivity, it is necessary to remove the arc extinguishing chamber from the circuit breaker and place it inside a spiral coil. As a result, when the arc extinguishing chamber is reinstalled on the circuit breaker device, mechanical parameters need to be readjusted, which involves a large workload and requires professionals. Using a new type of magnetic coil can surround the arc extinguishing chamber from the side, thus avoiding the need to disassemble the arc extinguishing chamber. At the same time, a single-chip microcomputer is used for synchronous control and data acquisition processing, improving the on-site testing sensitivity of the arc extinguishing chamber vacuum degree.