User Manual

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Siemens ET D1 · 2018/2019
Technical Information
Dimmers
General
16
Overview
Leading-edge phase principle
Conventional dimmers operate using the leading-edge phase
principle. At the beginning of each sinusoidal half-wave, the
dimmer blocks the current to the lamp, it is non-conducting. The
TRIAC (the electronic switch in the dimmer) is only connected af-
ter startup of a user-definable delay time t
z
, which energizes the
connected loads. In this way, the brightness of the connected
lighting medium can be infinitely adjusted. The interference volt-
ages produced by the switching oper
ation are damp
ened by
means of suitable filtering measures.
Trailing-edge phase principle
For this purpose, the load is switched on during the zero cross-
ing of each sinusoidal half-wave and switched off again on expi-
ration of the time t
z
. This allows changes to the r.m.s. value of the
lamp voltage, and thus the brightness. No interference voltages
are produced when switching on because the voltage has the
value zero. When turning off, any resonance points are damp-
ened, as the full load of the transformers is effective at this point.
No need for additi
onal systems for noise suppression. There is
no occurrence of the dreaded resonance points with their un-
pleasant humming or flickering.
Schematics
Rotary dimmers for ON/OFF and two-way switching (leading-edge or trailing-edge phase), 50 to 600 W, 50/60 Hz, 230 V AC,
incandescent lamps
Application in ON/OFF circuit (ON/OFF switching and dimmer control
from one point)
Application in two-way circuit (ON/OFF switching from 2 points and dim-
mer control from 1 point)
I2-6836a
t
t
z
10 ms
I2-6835a
t
t
z
L
N
L
I2_06794c
L
N
L
I2_06795d
Dimmer Two-way switch
Rotary dimmer for LV halogen lamps with solenoid transformer, for two-way switching (5TC8283)
For the protection of transformers, we recommend a miniature fuse (cor-
responding to the transformer rating)
L
N
L
I2_15458
~230 V ~12 V
LV
halogen-
lamp
Conventional
transformer