Schlüsselschalter

How do key switches work?

Key switches have different switching positions, which are set by turning the key on the rotary switch. The mechanical rotation leads to the connection or separation of circuits. The operator can only see the surface with a rotary lock, while the circuits behind it are usually hidden in a housing.

The key allows the switch to be protected against unauthorized use, as a switching process can only be initiated with suitable keys or extensive knowledge of how to overcome locks. This is why key switches are often installed in central locations in the circuit, so that no start-up procedure can be carried out without their key operation. As the best known example is the key switch on the ignition switch of a car, but also in industrial plants important processes can be coupled to a key switch.

The alternative to the key switch would be a closed housing with access control through a lock with a simple cylinder key and a simple rotary switch that can only be operated after the opening. However, in this two-step process, everyone could operate the rotary switch freely once the access door is open.
A key rotary switch combines the simple rotary switch with an extended effective access control.

What was the meaning of the individual functions and switching positions for key switches?

Switch position

Like all electronic switches, key switches are designed as NC, NO or CO contacts that can either connect or disconnect circuits. The electronic circuits are arranged differently behind the switch lock. When turning the key, different switching positions are visible to the user on the surface.

Various switching patterns are available in the Switching position filter:

The front number indicates the number of control circuits connected. There are key switches for 1/ 1 x or 2/ 2x circuits.

The positions off/on/on/off are set on an imaginary circle using the rotary key.

Example: 1 x off/on/on indicates a rotary key lock with three switching positions. The basic position is off, then comes on/on. The power-on functions can be different functions with the sole power-on of an application or the additional power-on to the already running applications.

In the practical example, a key switch with three switch positions can be connected to two coils. If you just insert the key, you are in the off position. If you turn it to the first on position, the circuit of the first coil is activated. If you turn to the second one-position, either the second coil is activated additionally or the first coil is deactivated and the second coil takes over the sole operation.

Caution: As mentioned above, the key switch can also function as a separator, corresponding to ‚a‘ in relation to an application behind it then just deactivated.

Functions

In the Functions filter, you can select key switches as latching or momentary action according to their operating behavior.

Latching: Latching means that the key switch remains in the set switching position, ERGO locks in place. This can be seen from the outside at any time. However, it is usually not possible to remove the key while the application is running when it is in a rotated position.

Momentary: Momentary means that the key switch is moved to a switching position when turned and initiates the switching process, but then returns to the previous position. For example, the ignition process for the PKW key lock is a momentary function.

0: Zero marks the starting position in which the key can be inserted or removed from the lock by pulling it out.

What was otherwise to be taken into account when selecting key switches?

In the filters, you can specify the automatic pre-selection based on further criteria when searching for a key switch suitable for your purpose, such as degree of protection, switching voltage and switching current.

Protection class

The degree of protection of key switches is important because they are intended for manual operation and there must be no risk of electric shock to the operator when the switch is in contact with the switch.

Key switches with the following protection types are offered in our shop:

• IP40

• IP54

• IP65

Switching current

The switching current refers to the current that may be present in the control circuit at the maximum on the key switch. There are key switches for low currents up to a maximum of 0.1 ampere, a large middle field and at the other end of the scale key switches for a maximum of 15 ampere switching current.

Switching voltage

The switching voltage also refers to the control circuit and is between 12 volts and 250 volts for the key switches in our shop.

Note: When selecting the switching voltage, also note whether the key switch is designed for DC, AC or both. AC means ambivalent current, i.e. alternating voltage, as it comes from conventional sockets, for example. DC is direct current, i.e. direct current, which can be generated, if necessary, by a converter in front of the key switch. Incorrect connection can result in damage to the key switch and other components in the surrounding circuit.

Questions and answers

How many keys do ich get to the switch?

As a rule, the key switch is supplied with two keys. However, pay attention to the notes in the specific product sheets, as there are deviations from the standard with the main and replacement keys. If you need more than two keys to your key switch for organizational reasons, contact our specialist department or the manufacturer in advance to order.