Relay is an electronic control device, it has a control system (also known as the input circuit) and the control system (also known as the output circuit), usually used in automatic control circuits, which in fact is a smaller current to control the larger current, a kind of "automatic switch". It is actually a kind of "automatic switch" to control a larger current with a smaller current. Therefore, in the circuit plays a role in automatic regulation, safety protection, switching circuits.
1, the working principle and characteristics of electromagnetic relays
Electromagnetic relays are generally composed of iron core, coil, armature, contact reeds and so on. As long as the coil ends plus a certain voltage, the coil will flow through a certain current, resulting in an electromagnetic effect, the armature will be attracted in the electromagnetic force under the action of overcoming the return of the spring tension suction to the iron core, which drives the armature's moving contacts and static contacts (normally open contacts) suction. When the coil is powered off, the electromagnetic suction also disappears, the armature will return to its original position under the reaction force of the spring, so that the movable contacts and the original static contacts (normally closed contacts) suction. This suction, release, so as to achieve the purpose of conduction in the circuit, cut off. For the relay "normally open, normally closed" contacts, can be distinguished in this way: the relay coil is not energized in the disconnected state of the static contacts, known as "normally open contacts"; in the on state of the static contacts known as "normally closed contacts "
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2, the working principle and characteristics of the thermal reed relay
Thermal reed relay is a new type of thermal switch using heat-sensitive magnetic materials to detect and control the temperature. It consists of a temperature-sensitive magnetic ring, a constant magnetic ring, a reed switch, a thermally conductive mounting piece, a plastic backing and some other accessories. The thermal reed relay does not use coil excitation, but the magnetic force generated by the constant magnetic ring to drive the switch action. Whether the constant magnetic ring can provide magnetic force to the reed switch is determined by the temperature control characteristics of the temperature-sensitive magnetic ring.
3, solid state relay (SSR) principle of operation and characteristics
Solid state relay is a two-terminal for the input, the other two terminals for the output of the four-terminal device, the middle of the use of isolation devices to achieve the input and output of the electrical isolation.
Solid state relays can be divided into AC and DC types according to the type of load power. According to the switch type can be divided into normally open and normally closed type. According to the isolation type can be divided into hybrid, transformer isolation type and photoelectric isolation type, photoelectric isolation type is the most....
Second, the main product technical parameters of the relay
1, the rated operating voltage
refers to the voltage required by the coil of the relay for normal operation. Depending on the model of the relay, it can be AC voltage or DC voltage.
2, DC resistance
is the DC resistance of the coil in the relay, which can be measured by a multimeter.
3, suction current
is the minimum current at which the relay can produce a suction action. In normal use, the given current must be slightly larger than the suction current, so that the relay can work stably. As for the working voltage added to the coil, generally do not exceed 1.5 times the rated working voltage, otherwise a large current will be generated and the coil burned.
4, release current
is the maximum current of the relay to produce release action. When the current in the suction state of the relay is reduced to a certain level, the relay will return to the unenergized release state. The current at this point is much less than the suction current.
5, contact switching voltage and current
is the voltage and current allowed to load the relay. It determines the size of the relay can control the voltage and current, the use can not exceed this value, otherwise it is easy to damage the relay contacts.