Technical information
479www.fagerhult.com • www.fagerhult.co.uk
Fagerhult oers luminaires with some unique functions. A sensor
based on microwave technology can be hidden in the luminaire
without aecting its design or insulation class. Fagerhult oers a
selection of luminaires with this technology to suit various areas of
application and needs.
The table shows how the properties of a microwave sensor dier
from those of a normal PIR (Passive Infra-Red) sensor. A microwave
sensor can detect movement on the other side of a thin wall, such
as one made of plaster. This function is particularly beneficial in
areas such as WC’s, whereby the light be switched on prior to the
door being opened. The sensitivity (or the detection range), howe-
ver, can be reduced to avoid erroneous detection.
A microwave sensor should not be placed close to ventilation
outlets or large metal surfaces as this may cause the sensor to
detect movement constantly. The settings for sensitivity, time after
last movement and lux threshold are adjusted in fixed steps on the
sensor module. The relay output can be loaded dierently, depen-
ding on whether you are switching on/o one or more luminaires,
or using the relay to adjust the lighting between various levels,
referred to as absence dimming or corridor function.
How does a microwave sensor work?
Like a radar, the sensor sends out a signal with a power rating of less
than 10 mW, which is then reected back. When the time of the
reflected signal changes, the sensor detects a movement. The power
of a sensor is around a hundredth of that emitted by a mobile phone.
Dimming
Luminaires with hidden microwave sensor
L1
N
PE
Connection ON/OFF – master luminaire and maximum two slave luminaire
L
N
E
Sensor
HF-ballast
Master luminaire
E
N
L
HF-ballast
Slave luminaire
E
N
L
HF-ballast
Slave luminaire
The luminaires are equipped with standard HF-ballasts for
On/O. The master and slave luminaires switch o after the
last movement and once the delay has expired.
Due to the properties of the sensor’s relay, only two lumi-
naires (two HF-ballasts) can be connected as slaves. It makes
no dierence if a number of sensor luminaires are connected
in parallel in the same function. The master luminaire is con-
nected with 4-core and the slave luminaires with 3-core.
Along with the Tridonics HF-ballast, the relay in the microwave
sensor can be used for a corridor function. Instead of discon-
necting the power to the HF-ballast, a control cable is connected
to the relay output of the sensor, thus regulating the light. The
relay is closed by someone’s presence and provides full lighting
immediately. After the last detected presence and the expiry of
the delay, the light is slowly adjusted down to 10 %.
As the relay is not loaded with any power, a larger number
of luminaires can be connected to the same control. Addi-
tional master luminaires can be added to the installation. The
installation can only be done as a 1-phase installation. Certain
luminaires with sensors and connections for corridor function
can only be used at 75 % sensitivity due to interference between
the frequency of the fluorescent lamps and the sensor. The
master luminaire and slave luminaires are connected with
4-core. The HF-ballast is the Tridonic Excel One4all or the ECO-lp
T5 (for compact fluorescent lamps, only the One4all is suitable).
In special cases, the One4all ballast can also be programmed for
other functions.
Ceiling mounting with max. sensitivity.
Sensitivity can be adjusted in fixed steps
of 20, 30, 50, 75 and 100 %.
NOTE! A microwave sensor can detect
movement on the other side of a thin
wall.
Comparison between sensors
Function/property Microwave sensor PIR sensor
Hidden in luminaire Yes No
Detects infra-red heat in motion No Yes
Detects objects in motion Yes No
Can be placed in a suspended luminaire No Yes
Detects through walls/glass Yes No
Adjustable detection range Yes No ¹⁾
Relay output Yes Yes
Adjustable O time Yes Yes
Adjustable lux threshold Yes ²⁾ Yes
On/O function Yes Yes
Absence dimming function Yes Yes
Slave connection Yes Yes
¹⁾ The detection range of a PIR sensor can be reduced by partially covering the lens
with tape, for example.
²⁾ Lux threshold can be used when the light of the luminaire is not directly reflected into
the photocell. This happens in luminaries with an opal diuser, so the use of a lux thresh-
old is not recommended with microwave sensors placed in luminaires.
Luminaire with sensor
Max. 4 m
360°
Ø < 8 m
Luminaire with sensor
The Discovery with microwave sensor.
L1
N
PE
Connections CORRIDOR FUNCTION– master luminaire and two slave luminaire
L
N
E
Sensor
HF-ballast
Master luminaire
E
N
L
HF-ballast
Slave luminaire
E
N
L
HF-ballast
Slave luminaire
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