(relay) principle of operation and characteristics
When the input (such as voltage, current, temperature, etc.) reaches a specified value, so that the output circuit to be controlled by the conductive or disconnect the electrical appliances. Can be divided into electrical quantity (such as current, voltage, frequency, power, etc.) relay and non-electrical quantity (such as temperature, pressure, speed, etc.) relay two categories. It has the advantages of fast action, stable work, long service life, small size and so on. Widely used in electric power protection, automation, motion, remote control, measurement and communication devices. 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, it is actually a smaller current to control a larger current of an "automatic switch". Therefore, in the circuit plays a role in automatic regulation, safety protection, switching circuits.
Relays have been widely used in computer peripheral interface devices, constant temperature system, temperature control, furnace heating control, motor control, numerical control machinery, remote control systems, industrial automation devices; signal lamps, dimming, blinker, lighting stage lighting control system; instrumentation, medical equipment, photocopying machines, automatic washing machines; automatic fire protection, security systems, as well as as the power factor compensation of the power grid capacitor switch and so on. Power capacitor switching switch and so on, in addition to the chemical industry, coal mines and other explosion-proof, moisture-proof, corrosion-resistant occasions have a large number of use 1, the working principle and characteristics of the electromagnetic relay
Electromagnetic relay is 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, thus generating 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, thus driving the armature of the 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 ".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 four-terminal device, the middle of the use of isolation devices to achieve the input and output of the galvanic 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 for the most.
Second, the main product technical parameters of the relay
1, the rated operating voltage
is 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 that the relay is allowed to load. It determines the size of the relay can control the voltage and current, the use of which can not exceed this value, otherwise it is easy to damage the contacts of the relay.
Wise Research Consulting data show that: at present, the country relay industry in the development of the main problems: the overall technology is backward. Mainly produce more than the patent protection period of the relay products, and imitation more than innovation, basically no breakthrough development; product development is not balanced. High-tech, high value-added products are few, while the ordinary electromagnetic, non-sealed products; investment products are few, for consumer products; unbalanced development of enterprises. Overall technical strength of enterprises, the economic benefits are not high; and labor-intensive and no independent development capabilities of assembly-type enterprises, due to low labor costs and other factors, relying on large-scale production, can still win some benefits; low value-added export products. Large export volume but low technology content, with cheap labor costs, export manufacturers compete to suppress prices, squeezing the limited market, earning hard-earned money. These problems have hindered the development of the relay industry. But visionary relay manufacturers have been based on the actual enterprise, and actively seek breakthroughs for the development of domestic enterprises to trip out a new development path.
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