Looking for a relay, what is a relay

Vacuum relays, characterized by:

Since the vacuum relay uses vacuum medium, it has the following excellent properties. 1. The vacuum relay is a relay that places the contact in a glass shell or ceramic shell drawn into a high vacuum, and uses vacuum as an arc extinguishing and insulating medium. 2. Vacuum has ideal insulation properties, in an ideal state may reach a dielectric constant of 80000V mm, because there is no oxygen in the vacuum, so it will not oxidize during use, so that the vacuum relay has a small and stable contact resistance during use.

3. Vacuum has good arc extinguishing performance. The arc in the vacuum is easy to diffuse, and it is not easy to cause wear and tear of the contacts, so the vacuum relay has the characteristics of long life and can be equipped with load switch. In general, vacuum relay has the characteristics of high breakdown resistance, fast arc extinguishing, large breaking current, small size, light weight and long life.

It is widely used in the fields of cardiac pacemaker, nuclear magnetic resonance imaging, high-frequency antenna coupling device, radar, capacitor discharge and other weak current control strong current 4. High electrical strength, large rated carrying current and conversion current, small contact contact resistance, stable work, low noise, small capacitance and inductance distributed between poles, small contact opening distance, low excitation power, fast breaking speed, contact sealing, not affected by air pressure, moisture, sand and dust or ** gas in the surrounding environment, and suitable for working in harsh environments.

The above is taken from the Encyclopedia.

I have used a withstand voltage DC 20kV, current 5A, driving voltage 24V, measured withstand voltage DC 6kV (higher voltage not tested, unconditional) under AC 3A current for half a month (1 minute on and off once, about 1W times) did not see obvious burn marks and oxidation of the contacts, the above is my actual use of this type of relay, for reference only. The disadvantage of this type of relay is that it is higher, and I use about 150 yuan for one. There should also be a 12V driver, a variety of parameter models, you can choose to buy one that meets the requirements, and then decide whether to use it after doing the test yourself, you can search for specific information on the Internet.

This kind of relay is not estimated to be available, because the n multi-relay we bought in our factory basically controls the high-voltage control end to control the on-off of high-voltage, but you can use two relays to cascade to achieve your function.

Relays are not available, while actuators may be. Because such a high voltage will break down a long air gap. The actuator can use an electromagnet to push the insulated connecting rod to drive the high-voltage contact engagement. There's no other good way.

Consider the method of oil-immersed contacts to reduce arcing.

Relay function:

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.

The role of intermediate relays

The general circuit is often divided into two parts: the main circuit and the control circuit, the relay is mainly used for the control circuit, and the contactor is mainly used for the main circuit.

Through the relay, the function of controlling another or several signals with one control signal can be realized, and the control of start, stop, linkage and so on can be completed, and the main control object is the contactor; The contact of the contactor is relatively large and the bearing capacity is strong, and the control of weak current to strong current is realized through it, and the control object is electrical appliances.

Notes:

1. Transportation and installation

The relay is a kind of precision machinery, so it is very sensitive to the abuse of the mode of transportation, many methods have been adopted in the manufacturing process to make the relay get the best protection during transportation, so in the factory inspection and the user's future use and installation, do not destroy the initial performance of the relay, in addition to the following points should be noted:

To prevent contamination of the surface of the lead-out end, direct contact with the lead-out should not be made, otherwise, it may result in a decrease in solderability. The position of the lead end should be consistent with the hole position of the printed plate, any improper fit may cause dangerous stress on the relay, damage its performance and reliability, please refer to the punch diagram in the sample to punch the hole.

Care should be taken to monitor the storage temperature and try to avoid storing the relay for too long (no more than three months is recommended). Relays should be stored and installed in a clean environment.

2. Apply flux

Non-plastic relays are highly susceptible to flux contamination and are recommended to use flux-resistant or encapsulated relays to prevent flux gas from ingress from the lead end and the gap between the base and the housing, and are suitable for multi-bubble flux or spray flux processes. Solder resistant relays are preheated and dried to further prevent flux ingress.

3. Welding process

Care should be taken not to damage the performance of the relay when using flux or automatic soldering, flux-resistant relays or encapsulated relays can be used for dip or wave soldering processes, but the maximum soldering temperature and time should be controlled depending on the relay selected.

4. Cleaning process

The overall cleaning of non-plastic relays should be avoided, and appropriate cleaning agents should be used for the cleaning of plastic relays, and it is recommended to use Freon or alcohol; Ultrasonic cleaning should be avoided as much as possible, as harmonics at ultrasonic frequencies can cause friction welding (cold welding) of the contacts and may cause the contacts to jam. Immediately after cleaning and drying, ventilation should be applied to bring the relay down to room temperature.

5. Installation direction

The correct installation orientation is important to achieve the best performance of the relay.

Relay (relay), also known as electric post, is an electronic control device, it has a control 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 to control a larger current. Therefore, it plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit. The relay coil is represented by a rectangular box symbol in the circuit, and if the relay has two coils, draw two rectangular boxes side by side.

At the same time, mark the word symbol "j" of the relay in or next to the rectangular box. There are two ways to represent the contacts of a relay: one is to draw them directly on the side of the rectangular box, which is more intuitive.

Relays generally refer to electromagnetic relays, that is, mechanical actions. The essence of the relay is to use a loop (generally a small current) to control the on-off of another circuit (generally a large current), and in this control process, the two circuits are generally isolated, its basic principle is to use the electromagnetic effect to control the mechanical contact to achieve the purpose of on-off, to electrify the coil with an iron core - the coil current to produce a magnetic field-magnetic field adsorption armature action on-off contact, the whole process is a process of "small current-magnetic-mechanical-large current".

A relay is an electrical control device, which is commonly known as a switch that is turned off or on when the conditions are met. A relay is actually an automatic switch that uses a smaller current to control a larger current. It plays the role of automatic adjustment, safety protection, conversion circuit and so on in the circuit.

It is widely used in remote control, telemetry, communication, automatic control, mechatronics and power electronic equipment, and is one of the most important control components.

Its basic principle is to use the electromagnetic effect to control the mechanical contact to achieve the purpose of on-off, and to energize the coil with an iron core - the coil current generates a magnetic field-magnetic field to adsorb the armature to act on and off the contact.

There are many types of relays, which can be divided into voltage relays, current relays, time relays, speed relays, pressure relays, etc., electromagnetic relays, induction relays, electric relays, electronic relays, etc., according to the use of control relays, protection relays, etc., and can be divided into relays and measurement relays according to the form of input changes.

A relay is a type of control device.

In layman's terms, it is a switch, which is turned off or on when the conditions are met. The switching characteristics of relays are widely used in many control systems, especially discrete control systems.

On the other hand, because the electronic circuits designed for a certain purpose ultimately need to interact with some mechanical equipment, relays also play the role of interfaces between electronic equipment and mechanical equipment. Relays commonly used in control are often used for relay control, signal transmission, and isolation amplification.

In addition, there are current relays used to limit current, voltage relays used to control voltage, automotive relays, electromagnetic voltage relays, small relays, power relays, home appliance relays and so on. It is with these different types of relays that it is possible for us to control different physical quantities and complete a complete control system.

When the 4th and 5th pins of the relay are connected to the power and there is a current flowing through, the coil will generate a magnetic force and draw the switch down. At this time, 1 and 3 are connected, and 1 and 2 are disconnected.

As for the ladder diagram of the PLC, you have to study it slowly, a simple ladder diagram, which is easy to understand by reading a book. Complex ladder diagram that looks very difficult.