Limit Switches
Limit switches are electrical switches that control the opening and closing of an electrical circuit by colliding with a moving mechanical part (such as a stopper or contact). Their core function is to detect the position or range of motion of an object. They are commonly used in automated equipment to limit mechanical travel, trigger safety protection, or perform sequence control.
1. What are the Working Principles of Limit Switches?
Triggering Mechanism: When a stopper on a moving part (such as a robotic arm or conveyor belt) strikes a switch contact (such as a roller or lever), the contact is compressed and displaced.
Circuit Switching: This displacement actuates an internal microswitch, closing the normally open (NO) contact or opening the normally closed (NC) contact, thereby connecting or disconnecting the circuit.
Reset: After the stopper is released, the contact automatically returns to its original position by a spring.
2. What are the Main Applications of Limit Switches?
Automated Production Lines: Detect workpiece position and trigger process actions.
Machine Tools: Prevent movement beyond safe limits.
Lifting Equipment: Monitor the upper and lower limits of elevators.
Door Control Systems: Ensure the smooth operation of automatic doors.
Hazardous Area Protection: such as chemical plant equipment monitoring.
3. What are the Types of Limit Switches?
By Actuation Mode: Snap-action switches (quick switching) and slow-action switches (slow switching, including BBM/MBB modes).
By Reset Mode: Automatic reset (automatic reset after the condition disappears) and manual reset (requiring manual intervention).
By Contact Type: Lever roller type (high-speed equipment), direct-acting type (low speed and light load), and universal type (multi-directional triggering).
4. What are the Technical Advantages of Limit Switches?
High Reliability: ABB limit switches, for example, can operate continuously under extreme conditions, with a mechanical lifespan of 30 million operations.
Flexible Installation: Supports IP66/IP67 protection, suitable for harsh environments.
5. Differences from Other Switches
Position Switches: Focus on continuous position monitoring, while limit switches are specifically designed for endpoint detection.