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Key switch

Key switch

The really safe option
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Key-operated switches or key-operated pushbuttons are electrical switches or pushbuttons that are fitted with a lock. This increases operating safety, as the switching operation can only be activated by persons carrying the corresponding key. In this way, different hierarchy levels can be implemented in the machine and system environment without major programming effort.

In the following, we will introduce you to a selection of different areas of application. In addition, we will go into more detail about the difference between key-operated switches and key-operated pushbuttons and explain the advantages of these actuators. This page will provide you with the information you need on this topic.

Key switch in the eCatalog

Key switch or key trigger - what is the difference?

The key triggers only one pulse in the circuit. After that, the key can only be moved back to the initial position and thus also removed. The lock therefore does not engage in another position. Such key switches are used when only one selection is to be made. For example, when selecting the floor in an elevator.

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A key switch has several latching positions, as it is used to set a switching state. This means that the switch closes or opens the respective circuit. This process is sometimes referred to by experts as "turning the key". It is used, for example, in automatic sliding doors familiar from shopping malls, where the state can be set with the help of the key. In this case, the key switch is not limited to two latching positions, but can have several, usually up to four. To stay with the example of the sliding door, these would be as follows: Permanently Open, Permanently Closed, Exit Only, Automatic.

By the way: A close relative of key switches are card readers, as they are used in many hotels. Here, the card takes over the role of the key. Fingerprint and iris scanners serve a similar purpose, but are currently only used in special cases.

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The switch with key - the advantages and possibilities

As a leading manufacturer in the field of man-machine communication, RAFI has a few categories of command and signalling devices in its portfolio. In terms of voltage, most key switches use 230 V. The key-operated switches of the different series usually offer up to four switching positions. Due to the shape of the keys, up to 10,000 different closures are thus possible. In addition, there is the additional function "authorization key": Depending on the key used, different switch positions can be keyed, i.e. only certain persons can reach the lock positions 1, 2, 3 or 4 of the control unit.

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In a fictitious production plant, this could look as follows: The plant operator starts the plant at the beginning of his shift by turning his authorization key to the maximum possible position 1. In the course of the shift, an unforeseen malfunction occurs. The plant operator calls the foreman for help. He uses his key of the next higher authorization level to call up a specific program within the plant control system in which he can diagnose the fault. There, he recognizes from the information displayed that a part is jammed. To remove the part, the shift supervisor must put the plant into maintenance mode with authorization key level 3. Once the part is then removed, work can continue for the plant operator. A possible level 4 here could be a master key that resets the entire plant and its controls to default settings if it is to be disposed of or rebuilt. These exemplary possibilities show well how variable the switches can be used in everyday work.

Another advantage of the key switch is its simple integration into HMI systems such as plant control systems, elevator control panels or alarm systems. Thanks to its practical dimensions, the product can be easily placed behind the front panel or flush-mounted. Added to this is the increasingly important design aspect. Key-operated switches that you purchase from a manufacturer that carries other control and signaling devices such as pushbuttons, switches or signal lamps ensure a harmonious appearance in combination with the other articles in the series. This is particularly important if the Human Machine Interface is not only to function perfectly and safely, but also to convey a uniform brand message. Of course, the easiest way to achieve this is to find a partner who accompanies you throughout the entire process and also has all the technologies in its portfolio: Touchscreens, housings, software, computers, joysticks, electromechanical systems, pushbuttons, illuminated pushbuttons, key switches and signal lights.

In summary, the advantages of key switches are as follows: Security through key-lock mechanism, additional security through long-term available key forms and spare keys, multitude of individually determinable functions, authorizations tailored to users, surface or flush mounting options, simple integration into complex operating systems and the matching appearance to further command and signaling devices. Translated with (free version)

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Countless application possibilities in everyday life

The purpose of use is usually determined by the importance of the switching operation. If switching operations have to be protected against incorrect or unauthorized operation, the key switches described above are usually used. They take over a filter function, so to speak. The following applications are common.

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Automotive Engineering

One of the best-known examples is starting a car. If only a simple switch were installed instead of the car key and lock, anyone could start the car. In some modern vehicles, this is already the case in a similar way with the familiar keyless-go systems, some of which are still vulnerable. Of course, the ignition lock is also used in other areas such as agricultural engineering or special vehicle construction.

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Potentially dangerous devices and machines

Some machines pose a danger to life and limb if used improperly by unauthorized persons. Here, a key switch ensures exclusive operation by qualified personnel. Examples would be waste or scrap compactors.

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Laboratory environment

Flammable chemicals, light-sensitive substances and complex filter mechanisms in the laboratory require maximum safety. This is why not only clean rooms with airlocks are used here, but often also secured circuits that can only be set in motion with the right authorization key.

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Maschinen- und Anlagenbau

Mechanical and plant engineering

As already explained above, many machines and systems have a multi-level authorization system. In addition, the emergency stop, also described in more detail above, is often reset by an authorization key in order to implement an additional safety level.

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Safety engineering

An alarm system is designed to protect data, buildings and information. But it only fulfills its purpose when it is armed. Some makes use a keypad for this purpose, often consisting of short-stroke keys with which a defined code must be entered. Alternatively or additionally, of course, a switch with a key can be used for this purpose. The alarm system is then activated or deactivated by turning it to one side or the other.

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Transport technology

Elevators or moving walkways in buildings that are not open to the public around the clock are often put to sleep overnight with the help of an authorization key. In addition, another lock in the elevator itself handles the actual starting or floor selection by the operator.

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Access control systems

These include door and gate systems of all kinds, such as the aforementioned sliding doors and their controls. Garage door openers are particularly worth mentioning here. Doors with sliding door drives, swing door drives or rolling door drives are often controlled with a door key. In addition to switching variants, key-operated pushbuttons are also used. In this case, the door only moves up or down as long as the key switch is turned.

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Public transport

On buses and trains, there are of course ignition locks on the one hand, but also so-called special traffic lights on the other. These often operate automatically, in other cases they can be controlled by the driver via a key system. These traffic lights ensure that local public transport has the right of way at certain intersections and thus ensure a smoothly functioning timetable - provided that the correct signal has been delivered.

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Payment systems

Many payment systems work via card readers, which, as already mentioned, are related to key switches. Some of these systems are additionally secured with a lock. For example, the supermarket cash register. If this has to be opened for the purpose of a complaint or incorrect booking, authorization keys are often used because sensitive data and information are involved.

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We encounter key-operated pushbuttons and switches almost every day in our daily lives, as they are used in many cases as an additional security level. Often, the aim is to prevent unauthorized persons from gaining access to premises or information. The difference between a pushbutton and a switch is that the pushbutton returns to its initial position after being pressed, while the switch locks into place. We hope that you have found all the information you were looking for.

Schlüsselschalter im eCatalog