Vacuum relay is a kind of relay whose contacts are in vacuum. It uses vacuum as medium. Usually it uses glass or ceramics as shell. The contacts are made of non-magnetic high conductivity metal.
Vacuum medium
Vacuum medium has many characteristics, such as very high voltage breakdown performance; very fast medium recovery rate; pollution in vacuum, combustion-supporting gas and vapor; arc in vacuum has flower shape, rapidly eliminating ionization, which makes vacuum relay show excellent performance, especially in high voltage, high power and radio frequency circuit applications. Out.
Characteristics of Vacuum Relay
Vacuum relay has high electrical resistance; high rated load-carrying current and conversion current, small contact wear and tear, long service life; small and stable contact resistance, low ohmic noise; relatively speaking, vacuum relay has small volume, small distributed capacitance and inductance between poles, small contact opening distance, low excitation power and fast breaking speed; sealed contacts are not affected by ambient air pressure, moisture, sand or gas. It can work in harsh environment.
purpose
Vacuum relays are widely used in radio communication equipment, radar, power supply, broadcasting and other electronic equipment, such as antenna coupling, tap conversion of radio frequency coil, antenna transceiver conversion, pulse forming network conversion, high-voltage high-power circuit quick switch, automatic grounding (leakage) protection. In addition, it can also be used in corrosive or explosive environments.
protective measures
Because the vacuum medium has very fast recovery rate and arc reduction characteristics, the vacuum relay will cause greater surge current when it is connected to capacitor load, and the instantaneous overvoltage when it is disconnected from inductance load. Considering these characteristics, sometimes the circuit should take appropriate protection measures.
The Position of Relay in Circuit
Electric "hot" conversion usually produces arc, ionized gas or metal vapor from contacts may cause fire jump or breakdown. For relays grounded in internal vacuum medium, to prevent damage caused by deficit or to interrupt greater power, relays should be connected to the end of the load (see figure). In addition, relays such as JPK-1, JPK-12 enclosures and ground insulation can be connected at any position.
