Classification of DC relays, there are several types of relays commonly used

Depending on the classification method, there are the following types of relays that are commonly used.

1) According to the principle of action, it is divided into: electromagnetic type, induction type, electric type, and transistor type relay.

2) According to the measured parameters, there are: electric relay such as current type, voltage type, power type, impedance type, and non-electric satin electrical appliances such as temperature type and pressure type.

3) According to the function, there are: intermediate relay, time relay and signal relay, etc.

The relay protection device is to realize the protection of the power grid according to the changes in the parameters and physical quantities of the relevant parts of the power grid during normal operation and failure. For example:

1) The relay protection that reacts to the change of current includes current quick break, timing overcurrent, reverse time overcurrent and zero sequence current protection.

2) The relay protection that reacts to the change of voltage has low voltage (or overvoltage) protection.

3) If the reaction current and the phase angle between current and voltage change, there is directional overcurrent protection.

4) The value of the change of reaction voltage and current. That is, if the impedance (or distance) from the reaction short-circuit point to the protection installation place, there is distance protection.

5) Reflect the difference between the input current and the output current, including transformer differential protection.

The relay is an automatic control appliance that turns on or off the small current control circuit according to a certain input signal to achieve long-distance control and protection. At present, there is news in the R&D department of Yuanze relay that the input amount of its relay can be current, voltage and other electricity, or it can be temperature, time, speed, pressure and other non-electricity, and the output is the action of the contact or the change of circuit parameters.

When the input voltage, current and frequency of the relay or the non-electric amount such as temperature, pressure and speed reach the specified value, the contacts of the relay will be connected or disconnected to the controlled or protected circuit.

The relay is generally composed of two parts: the input sensing mechanism and the output actuator, the former is used to reflect the level of input, and the latter is used to turn on or off the circuit. Commonly used relays have contacts, and the contacts have two states: on and off, and the change of state is driven by a certain mechanism.

The relay related to the action of the voltage relay contact and the action voltage of the coil is called the voltage relay, which is used for the voltage protection and control of the power drive system, and the coil of the voltage relay is connected in parallel with the load when used.

Features: The number of turns of its coil is large and the wire diameter is thin. Classification: According to the type of coil current, it can be divided into AC and DC voltage relays, and according to the size of the pick-up voltage, it can be divided into overvoltage, undervoltage and zero voltage relays.

The function of the intermediate relay is to increase the number of controlled lines or increase the allowable disconnection capacity of the contact, so as to achieve the purpose of distributing the control signal and power amplification.

There are many types of relays, which can be divided into voltage relays, current relays, time relays, speed relays, pressure relays, etc. According to the working principle, it can be divided into electromagnetic relays, inductive relays, electric relays, electronic relays, etc.; According to the use, it can be divided into control relays, protection relays, etc.; According to the change form of input quantity, it can be divided into whether there is a relay and a measurement relay.

The relay does not operate according to the input amount, the relay does not operate when there is no input quantity, and the relay acts when there is an input quantity, such as intermediate relays, general relays, time relays, etc.

The measurement relay is based on the change of the input quantity to act, the input amount is always there when working, only when the input amount reaches a certain value, the relay will act, such as current relay, voltage relay, thermal relay, speed relay, pressure relay, liquid level relay, etc.

The classification of relays includes: 1. Electromagnetic relays, 2. Solid relays, 3. Temperature relays, 4. Reed relays, 5. Time relays, 6. High frequency relays, 7. Polarization relays, and other types of relays: such as photorelays, acoustic relays, thermal relays, instrumentation relays, Hall effect relays, differential relays, etc.

There are thirteen kinds of relays classified according to their working principles or structural characteristics, namely: electromagnetic relays, solid relays, temperature relays, reed relays, time relays, high-frequency relays, polarization relays, photorelays, acoustic relays, thermal relays, instrumentation relays, Hall effect relays, and differential relays.

1. Electromagnetic relay: an electrical relay that works by using the suction force generated by the current in the input circuit between the electromagnet core and the armature.

2. Solid relay: refers to a relay in which electronic components perform their functions without mechanical motion components, and the input and output are isolated.

3. Temperature relay: a relay that acts when the outside temperature reaches a given value.

4. Reed relay: A relay that uses the reed action sealed in the tube and has the dual role of electric shock reed and armature magnetic circuit to open, close or convert the line.

5. Time relay: When the input signal is added or removed, the output part needs to be delayed or limited to the specified time before closing or disconnecting the controlled line relay.

6. High-frequency relay: a relay with minimal loss for switching high-frequency and RF lines.

7. Polarization relay: a relay that operates by the combined action of the polarized magnetic field and the magnetic field generated by the control current through the control coil. The direction of action of the relay depends on the direction of the current flowing through the control coil.

8. Other types of relays: such as photorelays, acoustic relays, thermal relays, instrumentation relays, Hall effect relays, and differential relays.

RelaysAs a control element, it can be summarized as follows:

1. Expand the control range: for example, when the control signal of the multi-contact relay reaches a certain value, it can be changed, interrupted and connected to multiple circuits at the same time according to the different forms of the contact group.

2. Amplification: For example, sensitive relays, intermediate relays, etc., can control very high-power circuits with a very small control quantity.

3. Comprehensive signal: for example, when a plurality of control signals are input into a multi-winding relay in the specified form, the predetermined control effect is achieved after comparative synthesis.

4. Automatic, remote control and monitoring: For example, the relay on the automatic device can be combined with other electrical appliances to form a program control circuit, so as to achieve automatic operation.

1.Categorized by the basic concept of action

Induction coil relays drive the armature and move part of the action based on the adsorption of the total current in the relay magnet coil to change the operation of the contact point system. For example, AC current induction relays, AC current pole relays, communication AC relays, binary differential protection relays, etc.

Induction coil relays interact with eddy currents on the flange plate of the relay by utilizing alternative magnetic fields and other changing magnetic fields, such as communication and communication binary relays.

When the total current of the heating relay heats the resistance band, the resistance band will have a trapped state characteristic of bending in one direction, and the relay will take advantage of this characteristic to function.

2.Classified by the total amount of current in operation

In DC circuits, most of the signal relays belong to this type of relay.

Communication AC relays work in AC circuits, such as communication AC filament conversion relays, FD type electrodecoders, JRJC binary two-position relays, electronic rectifier relays, etc.

AC and DC power relays can be used in AC and DC circuits, such as utility relays, various heating relays, etc.

3.Classified by speed of action

The action time of the armature of the fast-acting relay is less than that of most signal relays.

All normal operating relays operate in seconds.

The action time of the armature of the slow relay is more than a second, such as non-polar slow speed relay, heating relay, safety factor semiconductor time relay, etc.

4.Categorized by input method

Voltage relays are relays that act according to the change of circuit voltage, such as AC DC voltage relays used for motor loss of voltage and undervoltage protection; AC voltage relays for braking and commutation control of wound motors; DC voltage relays are used for forward and reverse braking of DC motors, etc.

Intermediate relays, which are used to increase the number or capacity of contacts in a control circuit, are essentially voltage relays, but their action values do not need to be adjusted.

Current relays, which act according to changes in circuit current, are used for overload and short-circuit protection of motors and other loads, as well as magnetic field control or loss of magnetism protection for DC motors.

Time relay is a relay with a certain time interval from receiving the signal to the action of the execution element, such as a relay used for delayed start resistance switching, motor energy consumption braking and production process program control when starting the motor.

Thermal relays are relays used for AC motor overload and phase failure protection.

Temperature relays are relays used for overheat protection or temperature control of various equipment.

Speed relays monitor the rotational speed of the power supply and the relays that change in steering.

The classification of relays includes: 1. Electromagnetic relays, 2. Solid relays, 3. Temperature relays, 4. Reed relays, 5. Time relays, 6. High frequency relays, 7. Polarization relays, and other types of relays: such as photorelays, acoustic relays, thermal relays, instrumentation relays, Hall effect relays, differential relays, etc.

The working principle of the relay: when a certain voltage or current is added to both ends of the electromagnetic relay coil, the magnetic flux generated by the coil passes through the magnetic circuit composed of the core, yoke, armature and magnetic circuit working air gap, and under the action of the magnetic field, the armature is attracted to the core pole surface, so as to promote the normally closed contact to be disconnected and the normally open contact closed; When the voltage or current at both ends of the coil is less than a certain value, when the mechanical reaction force is greater than the electromagnetic attraction, the armature returns to the initial state, the normally open contact is disconnected, and the normally closed contact is connected.

A relay is both a control switch and a control object (actuator). Take the fuel pump relay as an example, it is the control switch of the fuel pump, but the coil of the fuel pump relay can only form a loop through the grounding point of the electronic control unit when the triode is turned on in the electronic control unit.

Automotive relays are composed of a magnetic circuit system, a contact system, and a recovery mechanism. The magnetic circuit system consists of parts such as core, yoke, armature, coil, etc. The contact system consists of static reeds, moving reeds, contact bases and other parts. The recovery mechanism consists of a recovery reed or a tension spring.

Photo by Cheng Mingde) @2019