Limit switches are one of the unsung heroes of electrical engineering. Found virtually everywhere in both industrial and domestic settings, these electromechanical components can be used to:

• Control machinery
• Increase safety by creating an interlocking system
• Count passing objects

In simple terms, limit switches are an actuator that's mechanically linked to an electrical switch. When the actuator is activated, the switch will open or close depending on how it is set, and another action will occur.

Types of Limit Switch

There are four main types of limit switch based on the actuator used:

• Rotary/Roller Limit Switch
• Plunger Limit Switch
• Cat Whisker/Coil Spring Limit Switch
• Forked/Lever Limit Switch

Which one you choose for your application will depend on how the actuator needs to make contact with the object in question. For example, a plunger type limit switch might be used to control the light on a fridge door as the closed door pushes the plunger into the switch. A roller lever might be used to control the motion of electronic gates.

Although there are other types of switches and sensors that can perform the same tasks, the big plus of using a limit switch is its reliability and strength. OMRON are known worldwide for engineering and supplying quality products that you can depend on, so it makes sense to choose OMRON when looking for a limit switch for your task.

OMRON Safety Switches

The D4B-N series of safety switches features strong metal housings for use in industrial or other tough locations and includes a choice of lever and plunger actuators. They are part of a comprehensive range of safety solutions offered by OMRON that includes switches, scanners, emergency stop devices and interlocks.

SPDT Switches - A Type of Micro Limit Switch

As a variety of micro switch, Single-Pole Double Throw Switches (SPDT) use two limit switches that share a common terminal. One limit switch is generally set to "normally open" and the other is set to "normally closed". When the actuator or trigger is activated, the device will switch between open and closed or, depending application, on and off. This type of switch is commonly found in lighting, power supplies and safety systems. Which SPDT toggle switch you choose will largely depend on application and configuration.

The OMRON Z-series features a large switching capacity of 15 A and represents excellent value for money due to its high repeat accuracy. The plastic housing is perfect for use in less harsh environments or when encased in part of a larger system.