A seleção de um micro switch precisa de cinco etapas principais

Desde o seu surgimento na década de trinta, os microinterruptores foram continuamente desenvolvidos para atender a vários requisitos de aplicação, incluindo aeroespacial, electrodomésticos, controle de caldeira, pequena resistência de contato, sistemas de pulverização, equipamento de teste, timers and vending machines. Micros witches are typically used to detect temperature, position and liquid level.

Precision micro switches are usually available in three sizes: basic, with the operating lever, operating lever and housing. The micro switch adopts a plunger and spring design.

 

Whether engineers are looking for thermostats for residential heating or industrial boiler control, or level switches for large oil tanks, they need to consider five key characteristics: switch form factor, electrical requirements (voltage/current), confiabilidade (mechanical/electrical life), environmental factors (hazardous environments, temperature ranges), and agency approvals. Here are 5 key steps to help you choose the right micro switch for your application.

 

Etapa 1: Understand how the form factor of the switch affects other characteristics

Size is important when choosing a micro switch. The size of the switch is directly related to its characteristics, incluindo faixa de corrente, operating travel, e força operacional. Por exemplo, one of the smallest micro switches on the market measures 0.50″ x 0.236″ x 0.197″ (LxWxH). Although this tiny switch is suitable for detecting circuit status in compact circuit breakers, it typically only breaks currents of 0.1 para 3 amperes (UMA) and has a short travel.

Most Applications that require higher currents require larger switches. Por exemplo, micro switches for level detection in-tank applications must provide a long travel and withstand large currents. Typically in level switch applications, the switch drives the pump directly and carries a large current. It requires a large micro switch rated at 20A or 25A at 125VAC or 250VAC.

Tip: The smaller the switch size, the smaller the travel and the current that can be broken.

Além disso, the size of the switch also affects the operating force. Engineers need a switch with low operating forces and high current capability. But in fact, there is a compromise between these two parameters. Micro switches require stronger springs to maintain good contact while providing a large current withstand range, which will increase the switch’s operating force and shape size. Operating forces can range from 2 grams in pressurized pneumatic applications to 8 ounces in solenoid applications where a greater operating force is required. The largest switch on the market measures 1.94″ x 0.69″ x 1.3″ (LxWxH).

Engineers should also note the differential travel of the switch—the distance between the travel position of the switch and the reset position. The threshold varies depending on the application. Por exemplo, in temperature switch applications, the on/off operating points should be as close as possible, and the differential travel should be as low as 0.0001 inches. Contudo, in level pump applications, the differential travel is too close to cause the make-up pump to start and stop too frequently, shortening the pump’s service life.

Unionwell’s micro switches are available in various configurations to meet engineers’ specific needs.

 

Etapa 2: Conheça seus requisitos elétricos

Micro switches typically break currents from 5mA/5VDC to 25A/250VAC. The micro switch product line offers a range of products from low energy consumption to power load electrical versions for various applications.

Engineers must know the rated current and voltage (AC or DC) required for a specific application to select the appropriate switch. Since a wide range of equipment in all industries strives for low energy consumption, micro switches must be able to operate at low currents (logic level loads) and DC voltages.

Contudo, some applications require switches that can break high currents and voltages, such as industrial pump applications.

In addition to load requirements, engineers must select the right circuit. The switching contact must be one of the normally open (NÃO) and normally closed (NC) types. For NO-type contacts, there is usually no current passing between the contacts. When the switch is actuated, the contacts close and the circuit is connected. For NC-type contacts, there is usually a current flowing between the contacts. The contact opens, and the circuit is disconnected when the switch is actuated.

 

Etapa 3: Consider environmental conditions

Environmental requirements greatly influence the choice of microswitches, especially in applications that require high reliability and criticality, such as industrial control and medical equipment. Understand your application’s environmental conditions, including contaminants that may enter the switch in the air, the liquid in which the switch is located, and operating temperature requirements.

It would help if you sealed switches with a wide operating temperature range for applications under harsh environmental conditions. Highly reliable micro switches operate from -65 degrees Fahrenheit (-54 graus Celsius) para 350 degrees Fahrenheit (177 graus Celsius), making it easy to handle a wide range of applications. Ao mesmo tempo, it should also be noted that the protection level of the switch should be at least IP67 to prevent liquid ingress. It eliminates the need for a lot of time to design an enclosure that achieves the same degree of protection.

 

Etapa 4: Clarify the working service life requirements

The reliability of the switch is critical. How many electrical and mechanical operating cycles do you need for an application? Interruptores diferentes têm materiais de contato diferentes, housings and terminals to meet different applications’ requisitos de vida elétrica e mecânica.

A highly reliable micro switch can operate 10 million to 20 million times before mechanical failure and 50,000 para 100,000 times at maximum load before electrical failure.

As for the slight price difference between different quality switches, you need to consider the total use cost. Because you not only pay for the switch but also for ensuring that the switch runs trouble-free for a long time, in many cases, a lower warranty cost offsets the additional cost of using a more reliable switch during use.

 

Etapa 5: Check the agency certification requirements

Choosing switches that meet international electrical requirements can help simplify your product design for different areas. Some main standard certifications include UL certification in the United States, cUL certification or CSA certification in Canada, ENEC certification in Europe, CQC certification in China, and KC certification in South Korea.

When choosing a micro switch, you need to consider many factors, such as form factor, load requirements, operating environment and reliability, so it is important to understand the actual application requirements: What size switch do you need? What is the power rating required? Is it a low-voltage application? Does the switch need to be sealed? Does the switch need to withstand extreme temperatures? Is certification from an international organization required? Is it a critical application? Once these issues are figured out, choosing the right switch for the application becomes easier.

 

Unionwell Micro Switch Fabricante da China

Huizhou Unionwell Sensing & Control Electronics Co., Ltd é especializada em microinterruptores de qualidade para a indústria automotiva e linha branca de eletrodomésticos.

Os principais produtos incluem microinterruptores básicos, interruptores à prova d'água, pressostatos de ar, interruptores de teclado mecânicos, e interruptores de porta.

Um sistema one-stop será construído, cobrindo o desenvolvimento de produtos, moldagem de precisão, moldagem por injeção, estampagem de precisão, equipamento automatizado R&D, montagem, e testando.

A equipe de vendas profissional está à disposição para fornecer assistência e resposta rápida às solicitações de desenho 3D, cotações de preços, e acesso a um programa de amostra adequado que permite aos engenheiros testar e qualificar switches para suas aplicações de produtos finais.