Also commonly known as the miniature snap-action switch, the very first Micro Switch was developed in 1932 by Peter McGall in Illinois. In 1937 he created the Micro Switch Company, which was bought out by Honeywell thirteen years later. Although the name Micro Switch is trademarked, it has become synonymous with the miniature snap-action switch even when made by other manufacturers. Occasionally the two words are joined to become the ‘microswitch’.
How Does It Work?
The micro switch is designed to be activated by minimum force through a tipping mechanism which is usually, although by no means always, in the form of a lever. The switch contains three contacts, which are known as C for Common, NC for Normally Closed and NO for Normally Open. Depending on how the switch is designed, it will either allow or prevent the flow of current until the switching mechanism is activated. With a Normally Open switch the flow of current is not permitted until the switch is triggered into the closed position. A Normally Closed switch allows the flow of electricity until the switch triggers cessation of flow.
What Is It Used For?
There are literally thousands of uses for the micro switch thanks to its robust properties, despite being small and relatively cheap to manufacture. Often used in the control of electrical circuits, the switches are also widely used in the door-locking mechanism of microwave ovens. They are also commonly used in the levelling and safety mechanisms of elevators and can be used to detect jammed paper in photocopying machines.
An extremely popular use for the micro switch is in home security systems, where the movement of a door or window triggers the switching mechanism and causes the alarm to sound. Equally as useful in fire security systems, the switches also allow a vending machine to function, being triggered by the insertion of money and pressing of buttons to dispense the appropriate items into the drawer.
Many manufacturers make use of micro switches to identify blockages and back-ups on a production line. They can be set to halt the movement of a conveyor belt, for example, allowing time for the problem to be sorted out before production can start again.
There is a vast array of micro switches available in the market to perform a wide range of functions, so it is important to identify the correct size and style of switch for the job in hand. Some micro switches are designed for light use and these are best suited to functions such as security purposes or other low-use applications. Some switches are specifically tailored for frequent use, such as those used in vending machines and microwave doors, which may be in use several times a day, every day.
It is important to check the condition and performance of micro switches periodically to ensure that the mechanism remains in good working order. Any faulty or damaged switches should be replaced instantly to ensure safety and that performance standards are maintained.
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