Technical information

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Dimming
Comparison of control methods
Incandescent and low voltage light sources
The simplest way to dim an incandescent lamp is to use a thyristor,
or phase control. The thyristor clips o the leading edge of the sin
wave. Control of low voltage light sources, such as halogen, requires
a controller that is compatible with the transformer being used.
Transformers with iron cores, conventional transformers, are regu-
lated using a thyristor while electronic transformers generally de-
mand a transistor controller. These controllers clip, unlike thyristors,
the trailing edge of the sin wave. There are also electronic transform-
ers on the market that can operate both types of controllers.
Fluorescent lamps
Control of fluorescent lamps requires the light source to be operating
on control gear adapted and intended for dimming. It is not possible
to dim a light source that is operating on conventional control gear.
In general there are four dierent control methods for fluorescent
lamps – highlighted below.
Characteristics DALI DSI Phase control (impulse) 1–10 V
Addressable luminaire control 64 No No No
Group addresses 16 No No No
Logaritmic control Yes Yes Yes No
Control circuit polarity dependant No No - Yes
Switched o via the control circuit Yes Yes Yes No
Number of conductors to the luminaire 5 5 4 5
Control circuit in same cable, max length 300 m 250 m Unlimited 300 m
Multi-channel systems require an external central unit No Yes Single channel Yes
DALI
(Digital Adressable Lighting Interface)
Advantages:
Components from several dierent •
manufacturers can be included in
the same system.
Each unit in the system is adressable. •
Easy to modify and expand. •
Only one pair of control conductors •
even in multi-channel systems give
lower installation costs.
Polarity free control conductor re-•
duces the risk of wrong connections.
Can be controlled via an interface by •
a computer.
Can be connected to a BMS-system •
(LonWorks, EIB) via a gateway.
Note:
The system must be programmed •
before commissioning.
Programming is performed in dier-•
ent ways for products from dierent
manufacturers.
Max 64 addresses/system (Note that •
the interface for programming via a
computer requires an address).
Large systems can be built up via •
software/servers/gateways. This
type of system usually utilises
existing data networks (TCP/IP). An
example of this type of system is
winDIM@net from Tridonic.
1–10 V
(Analog)
Advantages:
Known system that is easy to •
understand.
Control units available from most •
manufacturers.
Note:
Some analogue 0–10 V control •
systems on the market are not ap-
propriate for the control of control
gear for 1–10 V DC as set out in
EN 60929.
The length of the control conductor •
can aect the control result.
1–10 V systems can only be control-•
led from one location (one control
unit).
DSI
(Non-addressable digital control)
Advantages:
All luminaires are controlled in the •
same way thanks to digital data
transfer.
Polarity free control conductor re-•
duces the risk of wrong connections.
Can be controlled via a computer.•
Note:
Components in the system are not •
addressable.
Multi-channel systems require each •
channel to have a separate control
conductor.
Only one manufacturer of the •
system.
Phase control
(Impulse – For example, switchDIM)
Advantages:
The system does not need an ad-•
vanced control unit.
Standard momentary switches can •
be used.
Only one extra phase conductor is •
required in the control circuit.
Note:
Wall switches must not be fitted •
with an indicator.
Max 25 HF-ballasts/system recom-•
mended.
Avoid mixing dierent brands in the •
system.
Control method refers to the type of signal transfer used between
the control unit/controller and the electronic control gear in the
luminaire. A number of the most common control methods are
highlighted in the table below.
The selected method also eects, apart from the components
included in the system, how low the lighting can be regulated, how
the installation is performed and the cost of the system. Digital
systems are generally more expensive than analogue, but they oer
technical and functionality advantages that truly substantiate the
extra cost.
In some applications it may be beneficial to combine digital
systems with basic analogue systems. Read more about this on the
DALI page.
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