All about Electromechanical Limit Switches

An electromechanical limit switch is a device used to detect the presence or absence of another physical object, normally, machinery that moves or travels.

Understanding the applications of an electromechanical switch can give us insight into the operational characteristics of this family of devices.

1.    Detects the activity of a car or garage door whether it is open or closed

2.    Detects when a vehicle’s door is not fully closed (safety interlock Limit Switch)

3.    Detect when a mechanical device passes the limit of its travel. The switch then trips arresting the motion and preventing the device from doing any damage

4.    Operator presence detection.

5.    Checks whether a computer printer head is in the right position for printing

6.    Used by CNC machines to provide a known reference point for incremental motions or to identify maximum travel limits for machine parts.

Considerations of Limit Switch Design

There are many types of limit switches. To pick the right one, designers must be familiar with the primary considerations to understand performance capability in their application.

Electrical Rating – Current flowing through the switch is the vital parameter that affects all other performance characteristics, including performance at temperature limits and electromechanical endurance.

Circuit Type – Momentary or maintained switch contact is another vital factor in the design. Most limit switches can be made in standard circuit options such as normally open/closed, and SPST or SPDT.

Actuator Style – The actuator can be as simple as a roller or ball switch type, or straight metal lever. To create customized travel distances which affect the lifetime and performance characteristics of the switch, angles can be varied. They can be designed to offer tactile feedback when humans operate them manually.

Duty Cycle – Your switch is turning on and off often? How often, once a week or twice a second? Extreme requirements here will dramatically affect your other switch design choices as you trade off durability with operation.

Mounting and Packaging – Limit switches can be made with a wide variety of mounting options which allow them to be placed in common and uncommon ways. They can be made entirely waterproof for deployment under exceedingly wet or even underwater operation.

Varieties of Mechanical Limit Switches

Most mechanical limit switches now available are of push-button variety. The switch depresses to complete the electrical circuit, when something comes in contact with the limit switch.  Spring pressure opens the switch as the object moves away from the limit switch turning off the circuit.

Standardized limit switches are manufactured with a variety of operator types including most commonly; lever, roller, plunger, and pushbutton limit switch types.

For over 60 years in its facility in East Hanover, CPI has designed and assembled robust electromechanical limit switches. For questions on the application of our switches, call us today or visit http://www.cpi-nj.com/