Staircase time switch
Staircase time switches (TLZ) are electromagnetically or electronically operated time relays for controlling the staircase lighting . Common names are also staircase or staircase light automat , in Switzerland minute scale , in German-speaking Switzerland also 3-minute automat .
General
Staircase time switches are controlled with a push button circuit via parallel push buttons . On all buttons, the light can be switched on for a specific time interval that can be set on the staircase light timer by briefly pressing the button. After this time, the lighting is switched off automatically. With some staircase light time switches you can also press the button; that is, if you press the button before the lighting switches off, the timer starts over. Normally, the buttons cannot be used to switch off; only some machines allow this function of early switch-off, for example by pressing the button for a longer time in the activated state.
Although today's staircase time switches work partially electronically, they are mostly still based on a coil relay: The start actuates a pull magnet that starts a clockwork or pneumatic delay element. In the past, mercury switches were widespread in this context ; they were tilted accordingly by the clockwork mechanism and were first used around 1911 as a time switch for electrical lighting systems that were new at the time. Other historical time switches worked with a Ferrari disk .
According to DIN 18015, the automatic switch-off has been equipped with a warning function for lighting systems in stairwells in apartment buildings since 1996. Before the timer is switched off, the end of the lighting time is signaled by briefly flickering or dimming down the lighting in order to enable timely re-touching. This function is known as switch-off warning.
So that the buttons can also be found in the dark, they are often illuminated by a glow lamp or light-emitting diode that is connected in parallel to the button via a series resistor . The staircase lighting timer must allow a certain flow of current to supply the signal lighting without starting.
Circuit variants
In all circuit variants, as shown in the adjacent circuit diagram, the staircase time switch is permanently supplied by L and N and switches the lamp cable via an internal switching contact. The protective conductor (PE), which is not shown , is not counted when counting the required conductors.
While special TLZ models are usually offered for the 3L circuit, the usual variants can generally be used for both the 4-way and the 3N circuit: The universal input required here must have switching pulses with L and N- Recognize potential. A coil winding from the input to the N or L potential can be used for this purpose. The coil circuit also serves to supply the glow lamps, which are usually connected in parallel to the buttons and only have a low power requirement below the detection threshold. In all cases the switching output is connected to L and the lamps are switched on. At the same time the time control for the shutdown is activated.
Four-wire circuit
In the four-wire circuit, the staircase time switch has an input for the switching impulses from the buttons and an output for the load to be switched. The external conductor L is switched as a signal to the switching input via the buttons and the L conductor is switched from there to the lamps. This results in two lines for the buttons connected in parallel and two lines for the loads (lamps) connected in parallel, a total of four conductors. Due to the principle involved, this circuit variant can be re-probed (increase in the time span by pressing several times) or off (as with the simple impulse switch ).
Three-wire circuit, L-keyed
In the L-keyed three-wire circuit, one connection serves as an input for the key signals and as an output for the load. Here the buttons switch the outer conductor L to the combined input / output, here the lamp circuit is already closed via the button at the moment of the button. At the same time, the input / output is subjected to external conductor voltage and switches L to this itself, so that the lamps continue to light up after the button is released until it is switched off again after the set time.
Due to the circuit, re-keying is not possible in this variant, since the staircase light timer cannot recognize the application of L when a button is pressed as long as it has switched this input output to L potential. Since this circuit, like the four-wire circuit, has a permanent N and L conductor, independent power supplies can be connected anywhere along the route, regardless of the staircase timer, which is why the circuit is often referred to as "with attic circuit".
Three-wire circuit, N-keyed
The N-keyed three-wire circuit switches the N-wire to the control input of the staircase time switch when the button is pressed, a permanent L-wire along the route is not available in this variant. This circuit variant can be re-probed due to the principle involved. The staircase time switch detects the connection with the N conductor through a permanent test voltage on the control line and thus activates its output.
Since the N conductor is touched in this variant, it is normatively impermissible in Germany and does not correspond to DIN VDE 0100 .
2-pipe models
For easy conversion of a normal light circuit, TLZ versions are also available to replace a normal on-off switch based on the 2-wire connection principle. The TLZ is inserted into the switch box and switched in parallel to a button.
Individual evidence
- ↑ Julius Springer (ed.): Advances in electrical engineering: Quarterly reports on the newer phenomena in the entire field of applied electricity theory, including electrical communications and signaling . tape 24 . Springer, 1911.
- ↑ Rudolf Krause: Brief Guide to Electrical Engineering: for teaching and practice in a generally understandable presentation . 4th edition. Springer, 1920, p. 188 ff .
- ↑ DIN 18015-2 Electrical systems in residential buildings, Chapter 4.3.3
- ↑ https://www.elektrofachkraft.de/sicherheites-arbeiten/beluchterungsschaltungen-in-mehrpartswohnanlagen
- ↑ https://www.conrad.de/de/treppenlichtzeitschalter-einbau-230-v-suevia-su200004-1487388.html