A relay is an electrical circuit that turns on or off a circuit based on changes in electrical quantities (such as voltage, current, etc.) or non-electrical quantities (such as heat, time, pressure, speed, etc.) to achieve automatic control and protection of the electrical drive device. Following the electrical generally consists of three basic parts: the sensing mechanism, the intermediate mechanism and the executing mechanism. The next small series for everyone to introduce the relay working principle and relay application skills. Relay working principle A time relay is a control device that uses electromagnetic principles or mechanical principles to implement time-delay control. When the coil is energized, the armature and the pallet are attracted by the iron core and momentarily move down, making the momentary action contact open or closed. However, the piston rod and the lever cannot fall along with the armature at the same time, because the upper end of the piston rod is connected with the rubber membrane in the air chamber. When the piston rod begins to move downwards under the action of the release spring, the rubber membrane is depressed downwards. The air in the air chamber becomes thin and the piston rod is damped and slowly descends. After a certain period of time, the piston rod is lowered to a certain position, and the delayed contact action is pushed by the lever so that the movable contact point is opened and the movable contact point is closed. The energization from the coil to the delayed contact completes the operation. This is the delay time of the relay. The length of the delay time can be changed by adjusting the size of the air intake hole in the air chamber. After the draw coil is de-energized, the relay recovers by restoring the spring. Relay application skills 1, to the correct selection To make good use of relays, correct selection of models is very important. First, we must have a thorough understanding of the nature, characteristics, and use requirements of the controlled objects and make careful considerations. The principles, applications, technical parameters, structural features, and specifications of selected relays must be mastered and analyzed. Based on this, the relay should be properly selected according to the actual conditions and specific conditions of the project. 2. Understanding the joints When the relay coil is not energized, the static and dynamic contacts in the disconnected state are called “normally open contactsâ€; otherwise, they are called “normally closed contactsâ€. A moving contact is normally closed with one static contact and is normally open with another static contact, and they are called "changeover contacts". In the same relay, there can be one or more pairs of normally open contacts or normally closed contacts (both can also be present at the same time), or there can be one set or array changeover contacts. 3, eliminate the contact spark method Because the current of the relay contact is small, there will be no arc between the contacts, but there will be “spark dischargeâ€. This is due to the presence of inductance in the contact circuit, and the overvoltage will appear on the inductor when it is disconnected, and it is connected to the power supply voltage. They are added together on the contact gap, and the contact gap just separated by a certain distance is broken down and discharged. Due to the limited energy, only spark discharge will occur. The alternating capacitance between the capacitor and the energy in the inductor will make the spark discharge appear hidden and become a high-frequency signal, and the spark discharge joint will also cause damage. , And will reduce the service life, so must try to eliminate, there are two kinds of practical anti-sparking circuit. 1. Its basic principle of action is to make the energy in the inductor pass through the rc without passing through the contact; 2. it is consumed on the load rl through the diode v when it is disconnected. Choose one of the applications. However, it should be noted that the rc parameter should be selected appropriately, and the parameter is mainly determined by experiments. Usually, the capacitor c can be selected according to the load current 1a/1 micro method. When using a diode, its positive and negative polarities should be connected correctly. 4. Increase the contact load method In use, if the load capacity of the contact can not meet the requirements of the use, several pairs of contacts can be used to solve in parallel. However, adjustments should be made before use so that the synchronization of the contacts can meet the requirements. Otherwise, it will be counterproductive. The best method is to use intermediate relays or contactors to increase the load capacity of the contacts. 5. When the return coefficient is not satisfactory The so-called return coefficient kf is a parameter that reflects the degree of cooperation between the suction force characteristics and the reaction force characteristics, that is, the difference between the relay action value and the release value. Relays of different uses often require different return coefficients when the relay's return coefficient does not meet the requirements for use. The role of the relay 1, to expand the scope of control. For example, when the multi-contact relay control signal reaches a certain value, the multi-circuit may be switched, disconnected, and connected at the same time according to the different forms of the contact group. 2, zoom in. For example, sensitive relays, intermediate relays, etc., can control very large power circuits with a very small amount of control. 3, integrated signal. For example, when a plurality of control signals are input to a multi-winding relay in a prescribed form, after a comparison and synthesis, a predetermined control effect is achieved. 4, automatic, remote control, monitoring. For example, relays on an automatic device, together with other electrical appliances, can form a program control circuit for automated operation. Editor's summary: The relay's working principle and relay application skills are introduced here, and we hope to help everyone. If you want to know more related information, you can pay attention to this website information. 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