The principle characteristics of electromagnetic relays, the working principle of electromagnetic re

An electromagnetic relay is a switch that uses an electromagnet to control the on/off of the working circuit.

2) The working circuit can be divided into two parts: low-voltage control circuit and high-voltage working circuit, and the low-voltage control circuit includes electromagnetic relay coil (electromagnet A), low-voltage power supply E1, switch S; The high-voltage working circuit includes the high-voltage power supply E2, the motor M, and the contact D and E parts of the electromagnetic relay.

3) Working principle - close the switch S in the low-voltage control circuit, the current generates a magnetic field through the coil of the electromagnet A, thereby generating a gravitational force on the armature B, so that the dynamic and static contacts D and E are in contact, the working circuit is closed, and the motor works; When the low-voltage switch S is disconnected, the current in the coil disappears, and the armature B disengages the dynamic and static contacts D and E under the action of spring C, the working circuit is disconnected, and the motor stops working.

As long as a certain voltage is added to both ends of the first circle, a certain current will flow through the coil, resulting in an electromagnetic effect, and the armature will overcome the tensile force of the return spring under the action of electromagnetic force attraction to attract the core, thereby driving the dynamic contact of the armature to engage with the static contact (normally open contact). When the coil is de-energized, the electromagnetic suction force also disappears, and the armature will return to its original position under the reaction force of the spring, so that the moving contact and the original static contact (normally closed contact) are released. In this way, it is engaged and released, so as to achieve the purpose of conduction and cutting in the circuit.

For the "normally open, normally closed" contacts of relays, they can be distinguished as follows: the static contacts that are in the open state when the relay coil is not energized are called "normally open contacts"; Static contacts that are turned on are called "normally closed contacts".

The working principle of the electromagnetic relay is: when the coil is energized, the iron core is magnetized to generate a large enough electromagnetic force, suck the armature and drive the reed, so that the moving contact and the static contact are closed or separated, that is, the originally closed contact is disconnected, and the original broken contact is closed.

When the coil is powered off, the electromagnetic attraction disappears, the armature returns to its original position, and the moving and static contacts return to their original closed or separated state. In the application, as long as the circuit that needs to be controlled is connected to the contact, the relay can be used to achieve the purpose of control.

Electromagnetic relay is an electromechanical component that uses input signals (voltage, current) to generate electromagnetic force in the core of the electromagnet and attract armature, so that the contact action can be opened, closed or converted to control. Electromagnetic relays are widely used in aviation, aerospace, ships, home appliances and other fields, mainly to complete the functions of signal transmission, executive control, system power distribution, etc., and are one of the key electronic components in each system.

Selection of electromagnetic relays

1. Understand the necessary conditions: the power supply voltage of the control circuit, the maximum current that can be provided; voltage and current in the controlled circuit; How many sets of contacts and what form of contacts are required for the controlled circuit. When selecting relays, the power supply of the general control circuit can be used as the basis for selection.

The control circuit should be able to provide sufficient working current to the relay, otherwise the relay engagement is unstable.

2. Pay attention to the volume of the appliance: if the chain is used for general electrical appliances, in addition to considering the volume of the chassis, the small relay mainly considers the circuit board installation layout. For small electrical appliances, such as toys and remote control devices, ultra-small relay products should be selected.

The working principle of the electromagnetic relay is that when the electromagnet is energized, the armature is sucked down to make D and E contact, and the working circuit is closed. When the electromagnet loses its magnetism when it is de-energized, the spring pulls the armature up and cuts off the working circuit.

An electromagnetic relay is an electronic control device, which has a control system and a controlled system. Usually used in automatic control circuits, it is actually a kind of "automatic switch" that uses a smaller current and a lower voltage to control a larger current and a higher voltage. Therefore, it plays the role of automatic auspicious adjustment, safety protection, and conversion circuit in the circuit.

It is widely used in automatic control, such as control circuits and communication fields in refrigerators, automobiles, elevators, machine tools. As long as a certain voltage is added to both ends of the coil, a certain electric coarse current will flow through the coil, resulting in an electromagnetic effect. The armature will overcome the tensile force of the return spring and attract to the iron core under the action of electromagnetic attraction, thereby driving the dynamic contact of the armature to engage with the static contact.

Other types

Thermal reed relay is a new type of thermal switch that uses thermal magnetic materials to detect and control temperature. It consists of a temperature-sensing magnetic ring, a constant magnetic ring, a reed switch, a thermally conductive mounting sheet, a plastic substrate and some other accessories. Thermal reed relays do not use coil excitation, but are driven by the magnetic force generated by the constant magnetic ring.

Whether the constant magnetic ring can provide magnetic force to the reed switch is determined by the temperature control characteristics of the thermosensitive magnetic ring.

The solid-state relay is a four-terminal device with two terminals as the input terminal and the other two terminals as the output terminal, and the intermediate isolation device is used to realize the electrical isolation of the input and output. Solid state relays can be divided into AC type and DC type according to the load power supply type, and can be divided into normally open type and normally closed type according to the switch type. According to the isolation type, it can be divided into hybrid type, transformer isolation type and optoelectronic isolation type, with the optoelectronic isolation type being the most.

The working principle and function of the electromagnetic relay is to use the electric gear magnet to control the switch on and off the working circuit, and play the role of automatic adjustment, safety protection, and conversion circuit in the circuit.

Electromagnetic relay is the use of electromagnet to control the switch on and off the working circuit, it has the control of the sail limb disorderly system (also known as the input loop) and the control system (also known as the output loop), usually used in the automatic control circuit, it is actually a kind of "automatic switch" with a smaller current and lower voltage to control a larger current and a higher voltage, so it plays a role in the circuit such as automatic adjustment, safety protection and conversion circuit.

Electromagnetic relay precautions:

1. Regarding the problem of contact resistance, the contact resistance between the contacts of the electromagnetic relay is generally milliohm level, and the contact resistance should be as small as possible in the case of poor ventilation in the use environment, which helps to reduce the temperature rise of the electromagnetic relay because the heat loss is less.

2. Regarding the load size of the contact, the load size of the contact is generally used in accordance with the specifications of the product.

3. Regarding the anti-drop performance, in the actual transportation and installation of the electromagnetic relay, it is necessary to pay attention not to let the electromagnetic relay fall from a high place, or vibrate violently, because that will cause the internal structure to be offside and affect the normal working parameters. <>

The role of electromagnetic relays is described as follows:

A relay is a device that uses the on/off of low-voltage and weak-current circuits to indirectly control high-voltage and high-current circuits. Electromagnetic relay is a kind of switch that uses an electromagnet to control the working circuit.

When the protected component of the power system fails, the relay protection device should be able to automatically, quickly and selectively remove the faulty component from the power system, so as to ensure that the fault-free part quickly recovers normal operation and prevents the faulty component from continuing to suffer damage. reduce the scope of power outages; By the early 90s, the development, production and application of integrated circuits and large-scale integrated circuit protection were in a dominant position, and the era of computer relay protection for intelligent information processing is currently being studied.