Photocell Control Cards
Photocells are programmed like switches so they are covered in the
switch section. There are two types of control card that are used with
photocells. The Single and the Three input photocell card.
Photocell
Connector
NOTE:
Connections
are Polarized
Connect Red
wire to 8Vdc
PCO-Photo Cell
Outdoor
Single Input Card
The single input card (Also called a "PCC 1" card) is the most fre-
quently used card. It is usually mounted in the panel that is closest
to the roof. It plugs into the bus and is powered from the bus.
It may also be mounted in its own 6"x4x4" box so that it can be
located closer to the photocell.
Two #18 wires are run out to the sensor. These should be a twisted
pair and run at a distance away from any current carrying high volt-
age conductors. The resistance of the sensors is over 2000 ohms
so for short runs # 24 AWG wire is acceptable.
The three input card called a "PCC 3de" Card can
accept three photocells. The “de” stands for digital
enable since it may be programmed to disable the pho-
tocells at certain times of the day.
LC & D sets up the cards for use with Photocells but in
fact the cards may be used with any type of sensor that
gives a linear output.
Another example would be a T emperature sensor.
The reference voltage supplied to the sensor is 8.2 Volts
dc provided by a 1% voltage reference. A total of 1 ma is
available for sensors. The analog inputs are read
between the voltages of 0 Volts and 4.1Vdc with a reso-
lution of approximately 1000 points.
The Indoor Photo Sensor is used for daylight harvesting
situations when a certain foot candle level is required. It
has a response curve close to that of the human eye.
Page 50
PCC3, Photocell Control Card with three Inputs
PCI-Photo Cell Indoor
PCC1, Photocell Control Card with one Input
PCC-3de Photocell Control Card
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