In electrical engineering, a limit switch is a switch operated by the motion of a machine part or the presence of an object. A limit switch can be used for controlling machinery as part of a control system, as a safety interlock, or as a counter enumerating objects passing a point.[1]
TMAZTZ Product Page
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, 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".
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 is directly controlled by the contacts of an industrial limit switch, but more typically the limit switch is wired through a control relay, a motor contactor control circuit, or as an input to a programmable logic controller.
A limit switch is an electromechanical device that is operated by a physical force applied to it by an object. Limit switches are used to detect the presence or absence of an object, and these switches were originally used to define the limits of travel of an object, hence their name.
A limit switch consists of an actuator with an operating head, a switch body mechanism and a series of electrical terminals used to connect the switch to the circuit it controls. The operating head is the part of the limit switch that is in contact with the target.The actuator contains a linear, vertical or rotary motion connected to the operating head which is then translated by the actuator to close or open the switch. The switch body contains the switch contact mechanism, the state of which is controlled by the actuator. Electrical terminals are connected to the switch contacts and enable wires to be connected to the switch via terminal screws.
Industrial machinery that performs automatic operations often requires control switches that are activated based on the motion involved in the performance of the machine.For repeated use, the accuracy of electrical switches needs to be reliable and their response time should be fast. Due to the mechanical specifications and performance parameters of different machines, factors such as size, operating force, mounting method, and travel rate are important characteristics for limit switch installation and maintenance. In addition, the electrical rating of the limit switches should be matched to the mechanical system load that will be controlled to avoid instrumentation failure.
TZ- stainless steel roller waterproof limit switch
When I open the refrigerator door, the light inside comes on. How did this happen? Yes! A limit switch is used to detect whether the refrigerator door is open or closed. Let's look at another application for your home. On many overhead garage doors, there is a limit switch that stops the door from moving when it reaches the fully open position. In most cases, the limit switch begins to operate when the moving machine or a moving part of the machine makes contact with the actuator or operating lever that activates the switch. The limit switch then regulates the circuitry that controls the machine and its moving parts. These switches can be used as guides for the control circuits of magnetic starters, allowing them to start, stop, decelerate or accelerate the function of the motor. Most switches are either hold contact or momentary contact models.
Limit switches offer several advantages inherent to their design.
Simple and straightforward design
For more limit swithinformation, please contact us. We will provide professional answers.
Works in virtually any industrial environment
High accuracy and repeatability
Low power consumption device
Can be used to switch multiple loads
Easy to install, robust and reliable
Can be used to directly switch higher levels of current without the need for auxiliary relay control
T4N-4A31R Manual Reset Safety Limit Switch
Limit switches also have a number of limitations, which means they may not be suitable for all applications.
Because they rely on mechanical action, they are typically used in equipment that operates at relatively low speeds
They are contact sensors, which means they must be in physical contact with the target to operate
They are subject to mechanical wear or fatigue over time and will eventually need to be replaced