Introduction of Limit Switch
Limit switch is one type Of " Contact Sensor" , In that there is Normally Open Contact & Normally Close Contact, In limit switch there is Plunger it is Directly Connected to NO & NC Contact if we press the plunger NO contact become NC & NC contact become NO, Working Principle same as Contactor ( DOL starter ) main difference is in contactor There is Coil to attract the Plunger But In Limit Switch Plunger is Operated Mecanically.Limit Switches is used mainly for Safety Purpose & to take Feedback for PLC in Automation industries........
A limit switch is a switch, usually mechanical, that is actuated by a moving part of some machine. Its operation is much like any other switch in that there are contacts that move when a plunger or lever on the outside of the switch is pushed. Internally there is an over center spring mechanism that snaps the switch open or shut in response to a gradual motion of the plunger or lever.
Types of Limit Switch
The common types of limit switches used in industrial applications include:
• Heavy-Duty Precision Oil-Tight: Also known as the Type C limit switch, this device is highly reliable due to its long electrical and mechanical lifespan. It features a straightforward wiring arrangement and relatively easy installation. The Type C can be equipped with a range of different head and body styles, including a more durable design that is watertight and submersible. It is available in a standard format, as well as with specialized reed contacts.
• Heavy-Duty Oil-Tight and Foundry: When load requirements exceed the capacity range for a precision oil-tight switch, a regular heavy-duty oil-tight model, or Type T, may be needed. It can handle operating sequences unavailable on the Type C and can withstand high trip and reset forces. The heavy-duty foundry limit switch, or Type FT, is commonly used in foundries and mills where Type T operating conditions are coupled with elevated temperatures and foreign materials that may jam other types of switches.
• Miniature Enclosed Reed: This limit switch, also known as Type XA, is a smaller and less expensive device formed from die-cast zinc. It contains a contact array featuring a hermetically sealed reed, which makes it well-suited for applications that require a high level of contact reliability or involve environmental stresses. The switch is normally prewired and can be placed in smaller or harder to reach areas.
• Gravity Return: The gravity return limit switch is usually employed in production line and conveyor operations involving small, lightweight components. This type of switch relies on gravity to reset its contact switches by exerting force on a lever arm and typically functions with a low level of torque. There are several varieties of gravity return switches, including spring return, roller type, lever type, top push, and maintained contact designs.
• Snap Switches: A snap switch is designed to instantly trigger as soon as the mechanism attached to the switch has moved a predetermined distance, regardless of the speed at which the moving part travels. Snap switches are commonly used in applications that require only basic contact parameters and can work with or without an operator. They are effective in machine systems that feature short movements or a slow rate of operation.
Precautions for All Limit Switches
Our Major Brands of Limit Switch are