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Interlocks: The Advantages of The Non Contact Proximity Sensors Are

A limit switch is an electromechanical device that uses contacts to make or break an electrical connection when an object comes into contact with its actuator. Limit switches are used widely in industrial machines and control systems to determine the position or movement of parts. They provide feedback to control circuits and can be used for safety interlocks or counting passing objects. Common applications include controlling garage door openers, ensuring correct positioning of parts in machines like printers or lathes, and indicating the status of gates or doors.

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71 views2 pages

Interlocks: The Advantages of The Non Contact Proximity Sensors Are

A limit switch is an electromechanical device that uses contacts to make or break an electrical connection when an object comes into contact with its actuator. Limit switches are used widely in industrial machines and control systems to determine the position or movement of parts. They provide feedback to control circuits and can be used for safety interlocks or counting passing objects. Common applications include controlling garage door openers, ensuring correct positioning of parts in machines like printers or lathes, and indicating the status of gates or doors.

Uploaded by

arshad
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Limit switch

a limit switch is a switch operated by the motion of a machine part or presence of an object.
They are used for control of a machine, as safety interlocks, or to count objects passing a point.[1]
A limit switch is an electromechanical device that consists of an actuator mechanically linked to
a set of contacts. When an object comes into contact with the actuator, the device operates the
contacts to make or break an electrical connection. Limit switches are used in a variety of
applications and environments because of their ruggedness, ease of installation, and reliability of
operation. They can determine the presence or absence, passing, positioning, and end of travel of
an object. They were first used to define the limit of travel of an object; hence the name Limit
Switch.

A limit switch with a roller-lever operator; this is installed on a gate on a canal lock, and
indicates the position of a gate to a control system.
Standardized limit switches are industrial control components manufactured with a variety of
operator types, including lever, roller plunger, and whisker type. Limit switches may be directly
mechanically operated by the motion of the operating lever. A reed switch may be used to
indicate proximity of a magnet mounted on some moving part. Proximity switches operate by the
disturbance of an electromagnetic field, by capacitance, or by sensing a magnetic field.
Rarely, a final operating device such as a lamp or solenoid valve will be directly controlled by
the contacts of an industrial limit switch, but more typically the limit switch will be wired
through a control relay, a motor contactor control circuit, or as an input to a programmable logic
controller.
Miniature snap-action switch may be used for example as components of such devices as
photocopiers or computer printers, to ensure internal components are in the correct position for
operation and to prevent operation when access doors are opened. A set of adjustable limit
switches are installed on a garage door opener to shut off the motor when the door has reached
the fully raised or fully lowered position. A numerical control machine such as a lathe will have
limit switches to identify maximum limits for machine parts or to provide a known reference
point for incremental motions.

The advantages of the non contact proximity sensors are:

No physical contact required with the target to be detected, therefore, no moving parts so
no friction and wear out.

Fast switching characteristics

Unlimited number of switching cycles since there is no mechanical contact

Can work in harsh conditions

Any type of target material can be detected.

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