Summary of relay components technology
The principle and characteristics of the relay
Relay is an electronic control device, it has a control system (also known as the input circuit) and control system (also known as the output circuit), usually used in automatic control circuit, it is actually a "automatic switch to control a larger current with small current". So in the circuit, it plays the role of automatic regulation, safety protection, conversion circuit and so on.
1. The working principle and characteristics of electromagnetic relay
Electromagnetic relay is usually made up of iron core, coil, armature, contact reed and so on. As long as the coil ends with a voltage and current will flow through the coil in a, resulting in electromagnetic effects, the armature will attract the electromagnetic force to overcome the spring to return to the core rally absorption, thereby driving the armature static and dynamic contact (normally open). When the coil is cut off, the attraction of electromagnetic will also disappear. The armature will return to its original position in the spring's reaction force, so that the moving contacts will be absorbed with the original static contacts (normally closed contacts). In this way, it is absorbed and released, thus achieving the purpose of conducting and cutting off in the circuit. For a relay's normally open or normally closed contact, it can be distinguished: the static contact when the relay coil is not energized, is called the "normally open contact", and the static contact in the connected state is called "normally closed contact".
2, the working principle and characteristics of the thermosensitive dry spring relay
The thermosensitive dry reed relay is a new type of thermosensitive switch using thermal magnetic materials to detect and control the temperature. It consists of a temperature sensing ring, a constant magnetic ring, a dry reed tube, a heat conduction installer, a plastic substrate and a number of other accessories. The thermosensitive dry reed relay is driven by the magnetic force produced by the constant magnetic loop without the coil excitation. Whether the permanent magnetic ring can provide the magnetic force to the reed tube is determined by the temperature control characteristics of the temperature sensing ring.
3, the working principle and characteristics of solid state relay (SSR)
Solid state relay is a terminal with two terminals, and the other two terminals are four terminal devices. The isolation device is used in the middle to realize the electrical isolation of input and output.
The solid state relay can be divided into AC type and DC type according to the type of load power supply. According to the switch type, it can be divided into often open type and often closed type. According to the isolation type, it can be divided into mixed type, transformer isolation type and photoelectric isolation type, and the photoelectric isolation type is the most.
Two. The technical parameters of the main products of the relay
1. Rated working voltage
It refers to the voltage required by the coil when the relay is working normally. According to the different types of relay, it can be AC voltage or DC voltage.
2. DC resistance
It refers to the DC resistance of the coil in the relay, which can be measured by a universal meter.
3. Absorption current
It refers to the minimum current of a relay that produces a sucking action. In normal use, the given current must be slightly larger than the absorption current so that the relay can work steadily. And the working voltage added to the coil generally does not exceed 1.5 times the rated working voltage, otherwise a larger current will be produced to burn the coil.
4. Release current
It refers to the maximum current of the relay that produces the release action. When the current in the state of the relay suck down to a certain degree, the relay will return to the state of the release of the non energizing. The current at this time is far less than the absorption current.
5. Switching voltage and current of contact
It refers to the voltage and current that the relay allows to load. It determines that the relay can control the size of the voltage and current, and can not exceed the value in use, otherwise it is easy to damage the contact of the relay.
Three, relay test
1. Contact resistance
By using the resistance gear of the universal meter, the constant contact and the moving point resistance are measured. The resistance should be 0, and the constant contact and the moving point are infinite. So it can be distinguished from the often closed contact, which is often open contact.
2, measuring coil resistance
available universal table R
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