How to choose the micro switch?
Release time：2018-10-24 Clicks： Click
Micro-switch is used in many places, production and sales are particularly high a switch in the choice of people have to consider a lot of problems, what is the specific problem? Let's introduce to you in detail below.
Micro-switch is a kind of contact mechanism with micro-contact interval and fast-acting mechanism, which is operated by prescribed stroke and force. It is covered by a housing and has a driving rod outside. Because of the small contact interval between the switches, it is also called micro-switch, also called sensitive switch.
Micro-switch has small spacing and large torque, and is often used in automotive electronics, military, testing instruments, medical devices and other fields. How to correctly select the micro switch and what factors should be noticed? Next, let's introduce how to correctly select the micro switch by Xiao Chen.
Step one: understand how the size of the switch affects other characteristics.
The size of the micro switch is directly related to its characteristics, including the current range, the operation force and the stroke.
First of all, larger switches are usually needed in applications where larger current is needed. For example, in fuel tank applications, the micro-switch used to detect the liquid level needs to be able to provide a large stroke and withstand a large current. This requires a large micro switch with a rated current of 20A or 25A at 125VAC or 250VAC voltage.
In addition, the size of the switch also affects the operation force. Ideally, engineers need a switch with low operating power and high current capacity. But in fact, there is a trade-off between these two parameters. In order to provide a large current bearing range while maintaining good contact, the microswitch requires a stronger spring, which increases the operating force and shape size of the switch.
Engineers should also pay attention to the differential travel of switches. The distance between the switch trip position and the reset position. The threshold will vary according to different applications. For example, in temperature switching applications, the switching point should be as close as possible, and the differential stroke should be as low as 0.0001 inches. But in the application of the level pump, the differential stroke too close may lead to the frequent start-up and stop of the supplementary pump, shortening the service life of the pump.
Step two: understand your electrical requirements.
Engineers must know the rated current and voltage (AC or DC) required for specific applications to select the appropriate switch. Since all kinds of equipment in all industries are dedicated to low energy consumption, micro-switches must be able to operate at low current and DC voltage. Of course, for industrial pumps, switches with high current and high voltage are needed.
Step three: consider environmental conditions.
Environmental requirements have a great impact on the choice of micro-switch. Understand the environmental conditions of application, including pollutants in the air that may enter the switch, the liquid in which the switch is located, and the operating temperature requirements.
For harsh environment applications, a sealed switch with a wide operating temperature range is required. High reliability microswitches can operate in temperatures ranging from - 65 to 350 degrees Fahrenheit (177 degrees Celsius) and can be easily applied to a variety of applications. At the same time, attention should also be paid to the level of protection of switches should be at least IP67 level, in order to prevent liquid intrusion.
Step four: define the working life requirement.
Different switches have different contact materials, enclosures and terminals to meet the electrical and mechanical life requirements of different applications. High reliability microswitch can operate 10 million to 20 million times before mechanical failure and 50 000 to 100 000 times under maximum load before electrical failure.
Step five: inspection institution certification requirements
Choosing switches that meet various international electrical requirements can help you simplify product design for different regions. Some major standard certifications include UL certification in the United States, CUL certification in Canada or CSA certification, ENEC certification in Europe and CQC certification in China.
In summary, when choosing microswitch, you need to consider a number of factors, such as shape size, load requirements, working environment and reliability, so you must understand the actual application requirements: what size of switch is required? What is the rated power required? Is it for low voltage applications? Does the switch need to be sealed? Do switches need to withstand extreme temperatures? Does it require certification from international organizations? Is it a critical application? Once these problems are identified, it will be easier to choose the switches that are suitable for the application.