Photocell and
Ambient Light Sensors for Dimming Ballasts
TYPICAL APPLICATIONS
• Open Office Areas
• Lobbies, Atriums & Hallways
• Cafeterias & Classrooms
CM-PC HIGHLIGHTS
• Ceiling Mount Photocell Sensor
• Works as Stand Alone Unit with
Power Packs
• Works in Occupancy Sensor System
• Adjustable Light Levels
• Operating Voltage: 12 to 24 VAC/VDC
• Output: SPDT; 1 Amp, Class 2
CM-ALC HIGHLIGHTS
• Ceiling Mount Ambient Light Sensor
• 0 to 10 VDC Dimmable Ballasts Only
• Works as Stand Alone Unit
• Adjustable Light Levels
• Maximum Sinking Capacity: 20 mA
CM-PC-ALC HIGHLIGHTS
• Combination of CM-PC Photocell and
CM-ALC Dimming Sensor in one unit
SPECIFICATIONS
• Size: Circular, 3.9” Dia., 1.34” Deep
• Sensor Weight: 7 oz
• Sensor Color: White
• Mounting: Ceiling Tile Surface Mount
• Relative Humidity: 20 to 90%
non-condensing
• Operating Temp: 14º to 160º F
• Storage Temp: -14º to 160º F
• UL and CUL Listed
• 5 Year Warranty
• Made in U.S.A.
LOW TEMP/HI HUMIDITY(-LT)
• Conformally Coated PCB
• Operates down to -40° F
ADJUSTMENT TOOL
Each sensor comes with an adjustment
tool that inserts into the side of the unit.
Its L-shaped handle allows for an easy
grip so adjustments can be made to the
correction indicators on the sensor for
light sensitivity settings.
Deadband
Sensitivity
CM-PC
(Photocell)
CM -ALC
DEADBAND
ADJUSTMENT
SENSITIVITY
ADJUSTMENT
(Dimming Sensor)
CM-PC-ALC
(Combination Unit)
BI-COLORED
LED
PHOTOCELL
(PC)
ALC
ADJUSTMENT
ALC
PHOTO
DIODE
T
he Sensor Switch Line of Photocell & Ambient Light Controller is designed to
achieve maximum control over light harvesting. The CM-ALC operates with commercially available 0 to 10 VDC dimmable ballasts to automatically dim the lighting
based on ambient conditions. The CM-PC is used for ON/OFF lighting control, or
it may be used as part of an occupancy sensor system (power pack not included).
The CM-PC-ALC is a combination of both the CM-PC and CM-ALC with photocell
and dimming features on one unit.
CM-PC ON/OFF CONTROL
The CM-PC turns the lights Off when enough
ambient light is present. A “Deadband” is set to
prevent the lights from cycling. For example, if the
lights produce 50 fc, and the minimum light level
in the space is 35 fc, then the “Setpoint” needs to
be slightly above 85 fc with a “Deadband” slightly
greater than 50 fc. The CM-PC will only turn Off at
85 fc and will turn back On when the light level drops
below 35 fc. Once On, the light levels must be higher than 85 fc to turn Off again.
NOTE: On a Sunny Day, manually Turn Off the lights and verify that there is enough
Ambient Light to provide minimum levels.
CM-PC DEADBAND SETTING
1. Manually turn the lights On and Off. Using a foot-candle (fc) meter, note the fc
contribution from the lights.
2. Set the Deadband slightly greater than the artificial light contribution:
Setting
Deadband Adjustment
Approximate Deadband
(Foot-Candles)
↑
Fully Clockwise
100 fc
↓
↑
TECHNICAL DATA
↑
Counterclockwise 50%
65 fc
Counterclockwise 75%
35 fc
Fully Counterclockwise
0 fc
CM-PC OFF SETPOINT: MUST HAVE ABUNDANT NATURAL LIGHT
1. Turn sensitivity adjustment fully counterclockwise. Lights will turn On (15 sec).
2. Manually turn Off lights. Adjust shades to minimum light level desired.
3. Turn lights back On.
4. Slowly rotate sensitivity adjustment clockwise until LED turns Orange.
5. LED stays Orange until lights turn Off (15 second delay).
Note: If LED turns Off, you were shadowing sensor, try again.
6. Lights should turn Off. If LED turns Green, lights will cycle back On: Deadband is
too small, increase by rotating Deadband adjustment slightly clockwise.
CATALOG INFORMATION
MODEL#
DESCRIPTION
COMPATIBILITY
CM-PC
CM-ALC
CM-PC-ALC
Low-Voltage Photo Sensor
Ambient Light Sensor for Dimming Ballast
Combined Photo and Ambient Light Sensor
Power/Slave Packs
0 to 10 VDC Dimmable Ballasts
Dimmable Ballasts/Power Packs
CM-PC, CM-ALC, CM-PC-ALC
CM-PC INPUTS/OUTPUTS
The CM-PC has 5 low voltage Class II wire leads. The Red (+VDC) and Black (common) power the sensor, and accept 12
to 24 VDC/VAC. The CM-PC uses a SPDT isolated relay for it’s output or interface with other control devices. The Brown
wire is connected to the center tap of the relay. When the CM-PC calls for Lights On (Dark), the White wire terminal closes
to the Brown. For Lights Off, the Brown-White disconnects, and the Blue wire terminal closes to the Brown.
STAND ALONE ON/OFF CONTROL: CM-PC WITH PP-20 POWER PACK
The PP-20 power pack connects to the lighting circuit. Low voltage class 2 wiring to the CM-PC On/Off Photocell. When
Dark, the lights will be On, when light outside, the lights will be Off. Red and Black from PP-20 provides 15 VDC low
voltage power. The
Brown wire connects
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OCCUPANCY SENSORS WITH PHOTOCELL/DAYLIGHT OVERRIDE
The PP-20 power pack connects to the lighting circuit. Low voltage class 2 wiring to the CM-PC On/Off Photocell and
occupancy sensor(s). When the space is occupied, the CM-PC may inhibit the lights from turning On if there is enough
ambient daylight. When unoccupied, the lights stay Off regardless of outside light levels. Red and Black from PP-20 provides 15 VDC low voltage power to
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stay Off.
CM-ALC 0-10 VDC AMBIENT LIGHT CONTROLLER
This sensor interfaces with commercially available 0 to 10 VDC dimmable
ballasts to achieve ambient light sensing, regardless of occupancy. The
grey and violet wires from each ballast connect to the like-colored wires
of the sensor. To obtain a certain brightness level in the room, adjust
the variable potentiometer located on the side of the housing using the
tool provided.
CAUTION: Ensure the photosensor faces away from all outside light
sources and is at least 24 inches away from the nearest light fixture
facing in the direction of the photosensor. Once the CM-ALC is adjusted,
NO POWER PACK REQ’D
connect the green wire for normal operation.
CM-ALC OPERATION
This sensor operates from a voltage source that supplies 1 to 30 VDC. The grey wire is common and the violet wire is positive
VDC. With ambient light detected, the voltage on the violet wire pulls down to approximately 0.5 V, with a maximum
of 20 mA sinking capacity. If no ambient light is present, the voltage on the violet wire releases to its nominal state (typically
10 VDC). The photosensing feature modulates the lights by varying the voltage on the violet wire: 1 VDC = 10% and 10
VDC = 100%. Note: The minimum dim level is based on the ballasts’ characteristics.
WARRANTY: Sensor Switch, Inc. warrants these products to be free of defects in manufacture and workmanship for a period of sixty months.
Sensor Switch, Inc., upon prompt notice of such defect will, at its option, provide a Returned Material Authorization number and a replacement product.
LIMITATIONS AND EXCLUSIONS: This Warranty is in full lieu of all other representation and expressed and implied warranties (including the implied warranties of
merchantability and fitness for use) and under no circumstances shall Sensor Switch, Inc. be liable for any incidental or consequential property damages or losses.
SENSOR SWITCH, INC.
900 Northrop Rd., Wallingford, CT 06492
(203) 265-2842 info@sensorswitch.com
www.sensorswitch.com
revised 04/01/2005
copyright Sensor Switch, Inc. 2005