How to choose a door limit switch

Among the circuit breakers, door limit switch is a device intended for the greatest number of application variants. As we have already seen in this article, door limit switches are in fact indispensable in many applications and sectors: from industry, to household appliances, to enclosures …

For a correct choice in the design phase, however, attention must be paid to different requirements: dimensions, interfacing and mechanical action, but also the type of electrical contact, the load to be controlled, the protection from humidity and air pollution.

Aspects to consider when choosing door limit switches

For a correct choice of a door limit switch, four simple steps are recommended:

1. Consult the CE certification of the product, verifying that the requirements of CEI EN 60947-5-1: 2005-11 (CEI 17-45) (Low-voltage switchgear and controlgear – Part 5-1: Control circuit devices and switching elements Electromechanical control circuit devices).
2. Choose the mechanical action best suited to the application: door limit switch manufacturers provide a choice of different types of actuating heads, with linear movement or with roller, slides or levers. In some cases, it’s necessary to provide for an adjustment phase of the mobile element on site.

1. Choose the type of electrical contact according to the function that the door limit switch must perform, between normally open or normally closed (NO/NC). There are models that incorporate both contacts allowing a single device to perform two functions simultaneously. A typical example is the use, on the same door limit switch, of the NC contact on the power supply of a moving part and the NO contact on an alarm signal tower. If the door limit switch is designed to act on a three-phase actuator, it generally contains three contacts of the same type.
2. If the door limit switch performs safety functions by interrupting the power supply of part of a machine or system, a device with manual reset must be chosen, so that a qualified operator can make sure that the conditions that caused the interruption have been removed or are not a cause of danger.

The Fandis door limit switch range consists entirely of models with IP65 protection degree, terminal block protected by cable gland, cover and protection class II. With these assumptions, all the models fully satisfy the possible industrial application needs.

If you want to know more about our electro-technical systems and all other Fandis products, visit our website fandis.com or leave a comment on this article. One of our technicians will answer you as soon as possible.