Size matters when choosing a microswitch. Switch size is directly related to its characteristics, including current range, travel, and operating force. For example, one of the smaller microswitches currently has dimensions of 0.50 inches by 0.236 inches by 0.197 inches (LxWxH). While this tiny switch is suitable for detecting circuit conditions in compact circuit breakers, it typically only interrupts 0.1 to 3 amps (A) and has a short travel.
Applications that require higher currents typically require larger switches. For example, in a fuel tank application, the microswitch used to detect the liquid level needs to be able to provide a large stroke and withstand a large current. Usually in liquid level switch applications, the switch directly drives the water pump and carries a large current. This requires a large microswitch rated at 20A or 25A at 125VAC or 250VAC.
In addition, the size of the small micro switch also affects the operating force. Ideally, what engineers need is a switch with low operating force and high current capacity. But in fact a compromise is required between these two parameters. To maintain good contact while providing a large current carrying range, the microswitch requires a stronger spring, which increases the operating force and size of the switch. Operating forces can range from 2 grams in pressurized, pneumatic-type applications to 8 ounces in solenoid valve applications (where higher operating forces are required). One of the larger switches on the market measures 1.94" x 0.69" x 1.3" (LxWxH).
Small micro switch engineers should also pay attention to the differential travel of the switch—the distance between the switch's tripped position and its reset position. Its threshold will vary according to different applications. In temperature switch applications, for example, the on/off operating points should be as close as possible and the differential travel should be as low as 0.0001 inches. However, in the application of liquid level pump, if the differential stroke is too close, it may cause the make-up pump to start and stop too frequently, shortening the service life of the pump.
Microswitch application
The micro switch is a contact mechanism with a small contact interval and a snap action mechanism, and the switch action is performed with a specified stroke and a specified force. It is covered with a shell and has a drive rod outside. A kind of switch, because the contact distance of the switch is relatively small, so it is called a micro switch, which can be used in such as computer mouse, car mouse, automotive electronic products, communication equipment, military products, testing instruments, gas water heaters, gas stoves, Small appliances, microwave ovens, rice cookers, floating ball equipment, medical equipment, building automation, power tools and general electrical and radio equipment, 24-hour timers, etc.
