Working principle of micro switch

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  • By:Italian B2b

A micro switch, also known as a snap-action switch or miniature switch, is an electromechanical device that is commonly used for various applications that require a precise and reliable switching action. The working principle of a micro switch involves the interaction between a mechanical actuator and electrical contacts. Here's a breakdown of its operation:

1. Actuator and Spring: A micro switch consists of a mechanical actuator, typically a lever or button, that can be actuated by external force or motion. The actuator is connected to a spring mechanism within the switch.

2. Contacts: Inside the micro switch, there are two electrical contacts, typically made of metal. These contacts are arranged in a normally open (NO) or normally closed (NC) configuration.

   - Normally Open (NO): In the NO configuration, the contacts are not touching when the actuator is in its resting position. The circuit remains open, and no current flows.

   - Normally Closed (NC): In the NC configuration, the contacts are in contact with each other when the actuator is in its resting position. The circuit is closed, and current flows.

3. Snap-Action Mechanism: The key feature of a micro switch is its snap-action mechanism. When an external force is applied to the actuator, it compresses the internal spring. As the actuator moves past a certain threshold point, the spring is released suddenly, causing a rapid movement of the actuator.

4. Contact Transition: The sudden movement of the actuator triggers the transition of the electrical contacts. Depending on the switch configuration (NO or NC), the contacts either close or open rapidly, creating a change in the electrical circuit.

   - NO Transition: In a normally open micro switch, the sudden movement of the actuator causes the contacts to close, completing the electrical circuit and allowing current to flow.

   - NC Transition: In a normally closed micro switch, the sudden movement of the actuator causes the contacts to open, interrupting the electrical circuit and stopping the current flow.

5. Switching Accuracy and Reliability: Micro switches are designed for precise and repeatable switching action. The snap-action mechanism ensures a quick and reliable transition of the contacts, minimizing the risk of contact bounce (rapid opening and closing of the contacts) and ensuring a stable electrical connection.

Micro switches find applications in various industries and devices, including appliances, automotive systems, industrial machinery, control systems, safety equipment, and more. They provide a robust and accurate means of switching electrical circuits based on mechanical actuation, offering versatility and reliability in diverse applications.

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