Data Sheet

7
I
Advantage of the “zero hysteresis” patented circuit:
ensures reliable switching without wasting energy
TYPE 11.41 “ZERO HYSTERESIS”
LIGHT DEPENDENT RELAYS
TRADITIONAL
LIGHT DEPENDENT RELAYS
set threshold
OFF threshold
ON/OFF threshold
ON threshold
Switch OFF level = Switch ON level.
Patented “zero hyseresis” circuitry
ensures reliable switching without
wasting energy.
“Traditional” light dependent relays
incorporate switching hysteresis to
prevent malfunctioning or tripping.
This results in an unnecessary delay
in switching off, and a resulting
waste of energy (over period T).
Brightness of the natural light
The NO of the light dependent relay is closed (light is switched on)
Advantage of the “light feedback compensation” principle:
avoids the effect of the lamps repeatedly “hunting” between On and Off, due to poor installation
Light dependent relay where
the lighting being controlled
does not influence the light
level seen by the light sensor
Traditional light dependent
relay where the lighting
being controlled influences
the light level seen by the
light sensor
Type 11.41 and 11.91 light
dependent relay with “light
feedback compensation”
recalculated
OFF
threshold
set threshold
set threshold set threshold
Correct functioning -
provided the light sensor
can be shielded from the
effects of the controlled
lighting switching
On and Off
Incorrect functioning where
the lamps cycle between On
and Off, because their effect
is being detected by the
light sensor
The innovative principle
of “light feedback
compensation” avoids the
annoying and damaging
effects of the lamps
repeatedly “hunting”
between On and Off, due to
poor installation
Ambient light level as measured by the light dependent relay's light sensor.
Ambient light + controlled light level as measured by the light dependent relay's light sensor.
Notes
1. It is good practice to try to achieve a correct installation where the light emitted from the lamp(s) does not influence the light level seen by the light
sensor, although the “light feedback compensation” principle will help when this is not fully achievable. In this case it should be appreciated that the
“light feedback compensation” principle may delay slightly the time of Switch Off - beyond the ideal.
2. The compensation principle is not effective where the combined effect of the ambient light and the controlled lighting exceeds a maximum value
(200lux for the 11.91, 160/2000lux for standard/high range of the 11.41).
3. The 11.41 and 11.91 types are compatible with gas discharge lamps that attain full output within 10minutes, since the electronic circuit monitors lamps'
light output over a 10minute period to achieve a true assessment of its contribution to the overall lighting level.
II-2018，www.findernet.com
11
SERIES
11 SERIES
Light dependent relays 12 - 16A