Limit switch, which one to use?

Do you know what a limit switch is? What is the best limit switch for each situation? There are several types of actuators for limit switches and in this article, the World of Electrical shows how to use each type of actuator.

In any electrical course, there are classes talking about components and their characteristics, usually these classes are called electricity technology.

The World of Electrical always seeks to bring different components for the electrician to know, because it is a great differential for the professional of the World of Electrical to know the components and know how to use them properly.

End of course

The limit switch is a mechanical sensor used to capture movement or position of a part. Normally the limit switch is used to identify when a part is at the limit or approaching the limit where this part can be positioned. In this way, a limit switch can be used for command, control and even safety systems.

Contact Box and Trigger

Now that we have explained what a limit switch is, we are going to show you three types of limit switch, in addition to several elements of action. The limit switch consists of the contact box and the driver.

Contact box and trigger.

In the contact box is where we have the cable connection. Notice in the image below that we have two metal contact boxes of different sizes, but there are also plastic boxes.

Metal contact boxes of different sizes.

In the contact box is where we have the cable connection.

The choice of box type will depend on the use of the limit switch. On more robust machines it is more interesting to use the metal box.

Another feature that can change is the size of the box, depending on the need for cable output. In the smaller box there is a single outlet for pressing the cable at the bottom of the limit switch. The larger box has an outlet in three directions, below and on the sides, this feature facilitates finishing and installation.

The need for output can change is the size of the box.

Now we go to the inside of the limit switch, on the inside we have access to the contact terminals, both limit switches have a normally open NO contact, and two normally closed NC contacts. To facilitate the finishing of the cable on the inside of the limit switch, there is a deeper part near the contacts.

Inside, we have access to the contact terminals.

A great advantage of this limit switch is that the actuator can be changed from the contact box. To remove the limit switch driver, simply remove the cover, then turn the upper latch and the driver is released. To insert another driver, just insert the new driver and turn the lock.

The actuator can be changed from the contact box.

Along with our limit switch, four different types of actuators came for the limit switch. The reinforced pin actuator which is for a short distance between the part and the actuator. In the pin actuator, the part meets the limit switch box.

Reinforced pin actuator, for a short distance between the part and the actuator.

Usually the pin actuator is used to stop machines according to the position of any part.

The upper roller pin actuator is used when the part passes the limit switch, however it is necessary that the part pass close to the limit switch actuator. In this actuator, the part always passes perpendicular to the limit position.

Pin actuator with upper roller is used when the part passes the limit switch.

This actuator is widely used to demonstrate the position of a part on a production line, for example.

The lever and stem actuator is used when the part will not pass as close to the end of travel. In the lever and stem actuator, the workpiece can come in several directions to activate the limit switch actuator.

Lever and rod actuator is used when the part will not pass as close to the end of travel.

Finally, we have the safety switch with a separate actuator. This safety switch is also a limit switch, the key is used to identify the position of safety gates. The safety switch also allows changing the position of the actuator according to the assembly to be made.

Safety switch with separate actuator.

This type of safety switch is widely used in electrical substations. When the door or grid is opened, a signal is sent to the circuit breaker to turn it off, thus ensuring the safety of those who opened the door, for example.

There is an actuator with vertical fixation when inserted in the actuator opening of the safety switch it switches the contacts. For example, when a grid is closed or opened, the actuator makes the switch contacts.

Actuator with vertical fixation, switch contacts.

The limit switch is used in several industrial processes, but contrary to what many think, the limit switch also has several residential uses and the best known without a doubt is the limit switch on the electric gate.