Why we using resistance and line monitoring with limit switch?

Limit Switch

  • Limit switches activate devices when the targeted object touches the actuator.

  • Limit switches can look like light switches (known as a maintained limit switch).


  • It stays on or off until forced

  • Limit switches control machines with moving parts and switching action mechanisms.

Why we are using resistance with limit switch?

A limit switch is a type of switch that is used to detect the presence or absence of an object or to limit the travel of a mechanism. When the switch is activated by the presence or absence of the object, it sends an electrical signal to the device it is connected to, such as a motor or a controller.

When a limit switch is activated, it can create a sudden change in the electrical current flowing through the switch. This sudden change in current can cause a voltage spike or transient, which can damage the switch or the device that is connected.

To protect the switch and the device from voltage spikes, a resistor can be added in series with the switch. The resistor limits the current flowing through the switch when it is activated, which helps to prevent voltage spikes

In addition to protecting against voltage spikes, a resistor can also be used to adjust the sensitivity of the switch. By selecting an appropriate resistance value, the switch can be made more or less sensitive to changes in the object it is detecting, allowing it to be customized to the specific application.

What is the need of Line Monitoring in Limit Switch?

Limit switches are used to detect the presence or absence of an object or to indicate the position of an object in a machine or system. Line monitoring is a technique used in limit switches to ensure that the switch is working properly and reliably.

In line monitoring, the limit switch is connected in series with the circuit it is controlling. This means that the limit switch is part of the circuit and any interruption in the circuit, such as a broken wire or a loose connection, will cause the switch to open and the circuit to be broken.

Line monitoring allows for continuous monitoring of the circuit to ensure that it is intact and that the switch is functioning properly. If the circuit is interrupted or the switch fails, an alarm or signal can be generated to alert the operator or control system of the problem.

Line monitoring is particularly important in safety-critical applications, such as in industrial machinery or elevators, where the reliable operation of limit switches is essential for preventing accidents or equipment damage.