What is Vauum Relay

Vacuum relay is based on vacuum technology. Using the part of magnetic circuit, the main function of the part of magnetic circuit is to change the electric change into the magnetic change and transfer it to the armature part. Because this part often needs to separate the vacuum from the atmosphere, there are higher requirements for the composition of raw materials and the size of sealing parts.

Vacuum relay features outstanding insulation performance, including exhaust structure and other main contact points, contact pieces, contact point rods

Catalog

1 Characteristics

2 Structure

3 definition of terms

4 typical components

Feature editor

Because vacuum relay adopts vacuum medium, it has the following excellent performance.

① Vacuum relay is a kind of relay which puts the contact in the glass shell or ceramic shell with high vacuum and uses vacuum as arc extinguishing and insulating medium.

② Vacuum has an ideal insulation performance, which may reach a dielectric constant of 80000v / mm in an ideal state. Because there is no oxygen in vacuum, it will not be oxidized in the use process, so the vacuum relay has a small and stable contact resistance in the use process.

③ Vacuum has good arc extinguishing performance. The arc in vacuum is easy to spread and not easy to cause contact wear, so the vacuum relay has the characteristics of long life and can be equipped with load switch. Generally speaking, the vacuum relay has the characteristics of high breakdown voltage, fast arc extinguishing, large breaking current, small volume, light weight and long service life. It is widely used in the field of weak current controlled strong current, such as cardiac pacemaker, nuclear magnetic resonance imaging, high frequency antenna coupling device, radar, capacitor discharge, etc

④ It has high electrical resistance, high rated carrying current and conversion current, small contact resistance, stable operation, low noise, small inter electrode distributed capacitance and inductance, small contact opening distance, low sulfonation power, fast opening and closing speed, sealed contact, not affected by the air pressure, moisture, sand dust or explosive gas in the surrounding environment, and is suitable for working in harsh environment.

Structural editing

Vacuum relay can be divided into two categories in structure.

① Exhaust type structure, the common feature is that there is an exhaust pipe, which needs to exhaust through the vacuum exhaust table. The armature action mechanism is located in the vacuum system, which controls the electromagnetic force generated by the current flowing through the coil to make the armature of the hinge in the vacuum act, with the action of moving contact to complete the opening or closing action.

② The diaphragm structure is characterized by no need to exhaust, and its vacuum system is directly obtained by vacuum welding furnace. The armature mechanism is located outside the vacuum room, and the movement of the armature is transmitted into the vacuum room through the elastic sealing diaphragm.

Term definition edit

① Contact form SPST-NO: single pole, single throw - normally open, closed when the coil is energized:

Spst-nc: single pole, single throw - normally closed, disconnected when the coil is powered on;

SPDT: single pole double throw;

DPDT: DPDT.

The contact form diagram is shown in table 6-1.

② Contact code form a: single pole single throw - normally open;

Form B: single pole single throw - normally closed;

Form C: single pole double throw,

Form 2c: double pole double throw;

Form P: single pole single throw - one hold;

Form R: SPDT - hold.

③ The test voltage is used to test the maximum voltage of the withstand voltage level of the relay.

④ The maximum voltage that the working voltage is allowed to bear under the working condition.

⑤ The maximum current allowed to flow through the relay contacts when the continuous load current is operating.

⑥ Coil breakdown voltage the maximum allowable voltage difference between the coil and the enclosure.

⑦ The contact capacitance is the capacitance between normally open contacts or between contacts and ground. The test method is based on GJB 360, and the frequency is 1kHz

⑧ The contact resistance of the closed contact in the contact resistance vacuum relay is calculated by measuring the voltage drop at 250mA.

⑨ Action time interval from coil power up to normally open contact closing (under rated coil voltage), action time includes contact bounce time.

⑩ Release time: the time interval from coil disconnection to normally closed contact closure

④ The operating ambient temperature specified by the operating temperature range relay.

Typical component editing

① The parts in the vacuum arc extinguishing chamber include contact point, contact piece, contact point rod and ceramic shell. The main function of this part is to bear high voltage and current. The parts in the arc extinguishing chamber generally require high surface finish, low air content, no air leakage and high temperature resistance.

② The main function of the armature part of the armature mechanism is to transform electrical changes into mechanical movements. The main parts are armature, iron holder, fork, shaft pin and spring. Because of the compact structure of the vacuum relay, the moving distance of the armature is usually very small, so the size requirements of this part of parts are very high, such as the planeness requirements of the armature, the fit size of the shaft pin and the armature hole, the burr, the shape of the spring and so on.