light switch
A light switch is a mechanical switch that can usually be operated by hand to switch the lighting on and off . It is part of the electrical installation .
,_by_Klugschnacker_in_Wikipedia_(18).JPG)
history
Originally, circuits were operated with open switches that only had an isolated switch handle and therefore did not offer adequate protection against contact. With the invention of the incandescent lamp by Edison and the advent of electrical installations , the need for a safe switch arose.
First of all, rotary switches were developed, which minimized the formation of sparks with a spring mechanism and were mounted at shoulder height (approx. 1.50 m). When standardizing the electrical installation, the current height of 1.05 m was suggested. The rotary switches were initially replaced by toggle switches, as these are easier to use. Rocker switches that were even easier to use later appeared. Modern switches with a large rocker are called flat switches. The latest development are switches whose switching contacts change over when actuated and maintain this switch position, while the rocker returns to its previous state after actuation. A changeover or cross connection can be operated with such switches as a push button circuit .
In the course of development, the previously mainly used mounting on the wall (surface-mounted) was abandoned and today, largely recessed mounted switches (flush-mounted) are used, as this type of mounting reduces the risk of damage and the possible exposure of live parts. On the other hand, sunk electrical cables increase the risk of electric shock when working on walls (e.g. nailing or drilling). Installation zones have been defined to minimize this risk. See under installation .
A special version is the moisture-proof switch , which is also available for surface and flush mounting.
material
In the past, light switches were made of porcelain in the surface-mounted version and operated as a rotary switch with a rotating mechanism, after which, due to the impact sensitivity of porcelain, those made of pressed fiber board ( Bakelite ) appeared. Today they are made from more modern plastics . Occasionally, especially in hospitals and other public facilities, light switches made of antimicrobial materials such as copper are used to prevent infections.
installation
With flush-mounted installation , electrical lines are laid in the so-called installation zones. Since these installation zones are standardized, it can be assumed that no cables have been laid outside this area. (Exceptions also confirm the rule here, so exercise caution!) Installation zones reduce the risk of accidents and damage during subsequent conversions, renovations, etc.
During installation, the external conductor must be switched in accordance with the electrical installation regulations (see also VDE ) so that there is no longer any voltage after switching off .
Switches for lighting systems are usually designed for a current of 10 A. In practice, however, lighting and socket outlet circuits are often combined with a 16 A fuse. Fusing the switches with 16 A for stationary lights is permissible because it can be assumed that the current will not exceed 10 A due to the design of the light. In DIN VDE 0100-510: 2012-06 it says in section 512.1.2: "When selecting equipment, the intended operating current (for alternating current, the effective value ) must be taken into account, which it should carry during undisturbed operation [...]"
There are two options for switching sockets: Use of overcurrent protection devices with a rated current of I n ≤ 10 A or use of installation switches with a rated current of I n ≥ 16 A (mostly multi-pole switches).
Components
Light switches in house installation are usually offered in three parts: insert , frame and rocker . The insert is the invisible part that contains the technical function. The rocker designates the visible switch , the frame the border, i.e. the transition to the wall. Frames are offered one to five times and group switches, dimmers, sockets of all kinds, controls and measuring sensors into one unit.
Types
counter
This component has at least two end positions in which the switch remains after actuation and thus closes or interrupts the circuit depending on the construction and position. This type of lighting control is mainly used in apartments.
Off switch
The circuit breaker has an input and an output and two positions: "open" (circuit interrupted) and "closed" (circuit closed).
Switches can be found, for example, directly on the light or in the connection cable, in the house installation in rooms with only one light switch. As a component for the house installation, pure circuit breakers are often not offered, since changeover switches can also be used as circuit breakers and the additional material required for production compared to a circuit breaker is minimal.
Toggle switch
The changeover switch has one input and two outputs; however, it can also be operated with two inputs and one output. It switches between output A and output B. This means that when the circuit is closed via A, it is interrupted via B.
According to DIN VDE 0100-460: 2002-08 section 465.1.2, single-pole switches must not be used in the neutral conductor. The misappropriation of changeover switches for the Hamburg circuit , which was often used in the past, does not comply with current standards and is therefore prohibited.
Location: With two changeover switches, a lamp can be operated from two locations. At least two cables must be drawn between the two switches. In the cross connection , two changeover switches are also used at the ends.
Series switch
The term series switch comes from the time when the switches were manufactured in the form of rotary switches with four switching positions.
In contrast to a double switch, a series switch denotes two independently operable off switches with only one common input and one output for each of the individual off switches. This can be recognized externally by a split rocker. It can be replaced by two off switches.
Location: series connection , for example lights with two groups of lamps, two groups of lights
Double switch
In contrast to a series switch, a double switch denotes two independently operable off-switches with two separate inputs and one output for each of the individual off-switches. This can be recognized externally by a split rocker. It can be replaced by two off switches.
D ouble changing switch
A double changeover switch describes two independently operated changeover switches with two separate inputs and two outputs for each of the individual changeover switches. This can be recognized externally by a split rocker. It can be replaced by two changeover switches.
Cross switch
The cross switch has two inputs and two outputs that are switched with two switch positions either straight or crossed, i.e. either input A is connected to output A and B to B or input A to output B and B to A. Cross switches can also be used as toggle switches or off switches.
Place of use: In cross connections as a third and further switch between two changeover switches , for example in bedrooms with light switches on the door and on each side of the bed. Today, cross-connections are often replaced by impulse circuits with buttons and impulse relays because the wiring effort is lower here.
Button
The button has only one basic position, into which it falls back by spring force as soon as you let go. So it only sends a signal (normally open contact) or interrupts the circuit (normally closed contact) for a short moment, it needs an additional control element in the light control, a bistable relay , which then keeps the circuit open or closed until the next control signal.
Location: Pushbutton circuits are used in stairwell lighting and wherever the light is to be operated from more than two locations.
dimmer
Dimmers are light switches which, in addition to switching the lighting on and off, also allow the brightness of the lighting to be set using a rotary control - or in the case of touch or sensor dimmers, by touching a sensor surface. They are also often built into table or floor lamps . They contain a phase control (for incandescent lamps and transformers) or a phase from edge control (phase dimmer, z. B. for electronic transformers of low-voltage halogen-systems)
Place of use: Anywhere where full or subdued lighting is required. With the exception of fluorescent lamps, on / off switches can be replaced by a suitable dimmer; those require an electronic ballast with a dimming function.
Twilight switch
Twilight switches switch automatically when an adjustable brightness value is exceeded or not reached. They are used as light switches or as roller shutter switches for shading. They have a hysteresis behavior and mostly delay circuits so that they do not switch on and off constantly when the ambient brightness fluctuates only slightly
motion detector
Motion detectors are increasingly replacing outdoor light switches today. When there is movement in the detection area, for example when a person approaches, they automatically switch the courtyard lighting on and off again after an adjustable time.
Radio switch
Battery-free
Batteryless radio light switches transmit the switching signal by radio to a receiver module, which switches the lighting circuit on or off. The energy required for this is obtained by actuating the switch (see Enocean ): By pressing the switch, a piezo element ( piezoelectricity ) is actuated, which converts mechanical energy into electromagnetic energy. Energy-saving electronics make it possible to generate coded radio signals from this energy, which have a range of approx. 30 m inside the building (up to 300 m outdoors). The coding ensures a clear assignment between the transmitter and receiver module.
Place of use: without restriction. Particularly suitable for office buildings in which the interior design is frequently changed. Batteryless light switches can e.g. B. can be mounted on glass walls or on wood, as no cable feed is required. Also suitable for use in old buildings, where no cable ducts have to be created for this type of switch, or - for the same reason - in wooden houses.
Battery powered
They work in a similar way to battery-free devices, but usually have a button cell as an energy source . The battery life expectancy is up to approx. 10 years. Then the cell needs to be changed. Compared to batteryless devices, these often have the advantage of greater functionality. Furthermore, the perceived pressure point is softer with battery-powered switches, since only one electrical contact has to be made here. For this reason, the construction height of battery-powered switches is nowadays identical to that of conventional switches, while battery-less switches currently have a significantly higher construction.
literature
- Ernst Hörnemann, Heinrich Hübscher: Electrical engineering specialist training in industrial electronics. 1st edition. Westermann Schulbuchverlag GmbH, Braunschweig, 1998, ISBN 3-14-221730-4
- Günter Springer: Expertise in electrical engineering. 18th edition, Verlag - Europa - Lehrmittel, Wuppertal, 1989, ISBN 3-8085-3018-9
- Winfrid Hauke, Rolf Thaele, Günter Reck: RWE Energie Bau-Handbuch. 12th edition, Energie-Verlag GmbH, Heidelberg, 1998, ISBN 3-87200-700-9
- Sven Bonhagen: Questions about home installation . Standards of the series DIN VDE 0100 (VDE 0100) in particular DIN VDE 0100-510 (VDE 0100-510) and DIN VDE 0100-540 (VDE 0100-540). In: The electrical and building technician. No. 11, 2009, p. 20
