Why test vacuum?

Why test the vacuum degree
The life of the vacuum interrupter consists of three parts: electrical life, mechanical life and vacuum life. Among them, the vacuum life is the most important, and the vacuum life must be monitored at any time, so a vacuum tester is required.
①Electrical life: rated voltage, rated current, rated short-circuit breaking current.
②Mechanical life: set during production, which is mainly determined by the life of the bellows. Generally,
the mechanical life of the switch set at the factory is 10,000 to 20,000 times.
③Vacuum life: When the interrupter leaves the factory, it is a variable quantity during the entire operation process. Therefore, it is necessary to monitor
the change of vacuum degree at any time to grasp the operating status of the vacuum interrupter.
●Why is the vacuum degree constantly changing, and it cannot be changed artificially after it is manufactured?
Because on the earth, vacuum is only a relative concept, and absolute vacuum cannot be achieved, which is mainly reflected in the
relativity of time and space.
●Why is there relativity in time?
The leakage of the vacuum interrupter is absolute, and no leakage is only a relative concept.
There are three reasons for the leakage of vacuum interrupter:
A. Slow leakage; that is, the leakage of the standard leak hole (tap point).
B. Leakage; that is, the interaction between glass molecules and air molecules.
C. Material degassing; that is, the air absorbed in the material will be released again under vacuum.
●Relativity
Pressure and vacuum are two ways to express a physical quantity: for every order of magnitude increase in vacuum, the pressure (
gas molecule density) decreases by one order of magnitude.
●Mean free path
The distance between two adjacent collisions of adjacent gas molecules is called the free path, and the average value is the mean free path. As the vacuum
increases, the mean free path increases accordingly.
2. Why does an interrupter need to be left still for a period of time before the second measurement can be started? What is the reason?
The vacuum measurement is based on the first measurement. The vacuum degree should be increased during continuous measurement, because each time the measurement is performed, part of the gas inside the interrupter will be ionized and absorbed by the two contacts, and it takes a certain amount of time to be released again.
3. Does our product have any special requirements for the object to be measured during a measurement? Is there a limit on the number of interrupters to be measured?
First, the object to be tested should be a vacuum interrupter. Secondly, its tube type should be one of the tube type curves, or an equivalent tube type (for example, the same interrupter has different models in Baoguang and Xuguang). We now have curves for most of Baoguang's products, and Baoguang is the largest vacuum interrupter manufacturer in the country with the most complete products. Therefore, you can ask the manufacturer for the corresponding relationship with Baoguang for other manufacturers' products. If you don't know the tube type, you can measure it according to the rated parameters of the circuit breaker and refer to Appendix 2 of the manual.
There is no limit on the number of tests. A lot of tests have been done on the durability and heat dissipation of the product, so you can use it with confidence. Our products are now being tested by Baoguang for factory inspection of interrupters. More than 500 interrupters are often measured continuously in one day, so there is no problem.
4. When our vacuum tester is unloaded (not tested), how should the instrument display be interpreted? The
vacuum value can still be measured when the input end of the instrument is suspended, because the suspended wire is like an antenna, which will generate an induced potential and then an induced current, but the value is generally very small at this time. Above 1×10e-4Pa, the error in measuring vacuum using the Penning discharge principle is already very large. Therefore, above 1×10e-4Pa, we only require resolution. 1×10e-4Pa is already the best arc extinguishing chamber, where discharges caused by ionization factors and other factors will produce ion flow. Therefore, it is more practical to use 1×10e-4Pa to display.