Paidong Industrial Zone Qiligang,Yueqing City,Zhejiang province,China.
Paidong Industrial Zone Qiligang,Yueqing City,Zhejiang province,China.
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    24 May, 2023
    Posted by elcb_admin
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    Relay Switch: Everything You Should Know

    What is Relay Switch?

    A relay switch is an electric switching device whose basic principle is to open and close a circuit by receiving an electronic signal from the outside. Relay switches have various sizes, shapes, and designs of different styles, so relay switches have a variety of additional applications in circuits.

    What are the types of relay switches?

    There are two basic classifications of relay switches, which are divided into electromechanical relay switches with moving parts, that is, movable contacts, and solid-state relay switches without moving parts, that is, without movable contacts. In practical applications, there are many different types of relay switch products.

    Electromechanical Relay Switch Electromagnetic relay EMR
    Electromechanical Relay Switch

    Electromechanical Relay Switch

    The electromechanical relay switch is a kind of mechanical switching device, which is driven by magnetic force to open and close the circuit. It is basically used for high-power electrical equipment. For some circuits that require signal control, the electromechanical relay switch is a high-quality and low-cost product.

    Solid State Relay Switch

    The solid-state relay switch is an electronic switching device that uses semiconductors and electrical switching elements. Through the operation of the electronic circuit, when an external voltage is applied to the switch control terminal, the solid-state relay switch will be turned on or off.

    A solid-state relay has no moving parts, reducing wear and tear, and resulting in a longer lifespan.

    Solid State Relay Switch SSR
    Solid State Relay Switch

    How Relay Switches Work?

    Relay switch contact types can be classified according to different actions, by energizing the coil in the relay, there are several different connections, namely: Single Pole Single Throw – SPST, Single Pole Double Throw – SPDT, Double Pole Single Throw – DPST, Double Pole Double Throw – DPDT.

    At the heart of an electromechanical relay switch is an electromagnet, one of the building blocks. In practical applications, when the electromagnet is turned on with a small current, the electromagnet will pull the metal switch on the second circuit to make the second circuit run or close. In this way, the process of small current controlling large current is realized.

    What is the difference between a relay switch and a normal switch?

    A switch is an electrical device used to turn an electrical circuit on and off. The switch provides a measure of current protection control and is manually operated by a handle. Like wall switches at home, they are the most common mechanical switches. Compared with relay switches, the response time of ordinary switches is slower.

    Relays use low-power signals to drive circuit currents, and control circuits by opening and closing contacts. They are usually used to protect large electrical system equipment from damage and automatically disconnect the circuit when the power in the operation of the equipment exceeds the rated range.

    Both relay switches and ordinary switches are basic electronic components in daily use. Relay switches are often used in more sophisticated or smart home equipment applications. Ordinary switches are cheaper and suitable for low-budget equipment applications. Both have advantages and disadvantages.

    Common Applications of Relay Switches

    Relay switches are used in a wide range of applications, ranging from small household appliances to large industrial appliances.

    1. Lighting control system. Indoor lights and street lights can be controlled by relay switches, which can be used according to the sunrise and sunset time or set a fixed time, and the working status can be easily controlled.

    2. Traffic control system. The traffic lights at traffic intersections can be controlled by relay switches to set the alternating time of red-yellow-green signal lights.

    3. Automobile control system. Car headlights and alarms can be controlled by relay switches, a type that controls large currents with small currents.

    4. Equipment protection system. In the circuit, the protective relay is one of the key components. Used to detect dangerous conditions during equipment operation and provide a safer circuit system.

    5. Agricultural irrigation system. The automatic sprinkler irrigation system in the lawn and crops can be controlled by a relay switch, and the equipment is turned on at a fixed time every day to control the continuous working time of the equipment, which is helpful for saving water.

    Agricultural Irrigation System Watering Crops Farm Land Agriculture
    Agricultural Irrigation System Watering Crops Farm Land Agriculture

    Why Relay Switches Fail?

    In practical applications, when operating equipment on the circuit, the relay switch may fail. In this case, we need to confirm the specific cause of the failure in order to solve the problem.

    Possible faults are as follows:

    1. There is no voltage input on the relay switch. The relay switch may be wired incorrectly, with loose terminal connections.
    2. The model and specification of the relay switch do not match. The circuit voltage does not match the rated voltage of the relay switch, resulting in the relay switch not working properly.
    3. The relay switch product is damaged. The internal coil is disconnected, causing deterioration over time and loosening of internal parts.
    4. The circuit is not working properly. The wires are in poor contact, the wiring distance is too long, and the load equipment is damaged.

    How to Test a Relay Switch?

    The relay switch is a kind of electromechanical device, which will always be worn and consumed during use, and loses the ability to work over time. In order to understand the real-time status of the relay switch, we can use the following methods to test whether the relay switch can continue to work normally:

    1. Test the relay switch with a multimeter
    2. Use the required equipment to build a simple circuit to test the relay switch

    However, if we use the smart relay switch SY2, we can check the status of the relay switch anytime and anywhere on the mobile APP, no need to test the relay switch, remote control, high convenience, and a step in building a smart home. What is a Smart Relay Switch?


    This article briefly introduces the relevant knowledge of the relay switch, what it is, what types it has, and the actual application. Relay switches are available in many types for a very wide range of applications and provide substantial assistance.

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