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Reed Relay,Solid State Relay

Last Update Time: 2018-10-09 16:09:52
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Reed Relay

Spring Relay is a new and simple miniature relay element.There are two common types of dry reed relays and wet relay relays.They have the advantages of fast speed,stable operation,long mechanical and electrical life,and small size.

( 1 ) Dry reed relays consist of one or more dry reed switches ( also known as dry pipes ) and excitation coils ( or permanent magnets ).

In the dry reed pipe, there is a group of magnetic guide reed, which is encapsulated in the glass tube filled with sentient gas, and the magnetic guide reed is also a contact reed, which plays the double of circuit switch and magnetic conduction heavy effect. When the coil is connected with a current or the magnet is close to the dry reed pipe, the ends of the two reeds form a polar opposite pole and attract each other. When the attraction is greater than the reaction force of the film, the contact between the two makes the normally open contact close; when the current in the coil is reduced or the magnet is far away, the attraction between the reeds is smaller than that of the reed, and the movable reed returns to the initial position, the contact is disconnected.

( 2 ) Wet reed relays are developed on the basis of dry reed relays. It is filled with mercury and high pressure hydrogen in the dry reed pipe, so that the contacts are infiltrated by mercury and become mercury contacts, and the hydrogen gas continuously purifies the mercury on the contacts, there is always a pure mercury leg on the contact. This kind of mercury-filled reed pipe becomes a wet reed pipe. The reed relays made of wet capital tubes are called wet reed relays.


Solid State Relay

Solid State Relay ( SSR ) is a new type of contactless switching device developed with modern microelectronic technology and power electronics technology, it is also a kind of power switch which can isolate the electronic control circuit and the electric circuit. The solid state relay is generally a four-terminal active device, in which there are two input control terminals, two output terminals, and an isolation device between the input terminal and the output terminal, as long as the direct current or pulse signal is added to the input terminal, the output terminal can switch on the switch, and the function of the equivalent electromagnetic relay is realized. Its shape is shown in Figure 2-43. 

The solid state relay has no contact, no spark, reliable operation, fast switching speed, no noise, no electromagnetic interference, and strong anti-jamming capability, and long life, small size, vibration resistance, explosion-proof, moisture-proof, anti-corrosion, can be compatible with TTL, DTL, HTL and other logic circuits, a large current load is directly driven by a small control signal. Solid state relay has been widely used in computer peripheral interface device, electric furnace heating, constant temperature system, CNC machine, remote control system, industrial automation devices, signal lighting control, instrumentation and medical equipment and other fields.