SPECIALTY CONCEPTS TIMER
SCT
(
Photovoltaic Load Timer
Installation and Operation Manual
SPECIALTY CONCEPTS, INC.
8954 Mason Ave.
Chatsworth, CA 91311 USA
MODELS COVERED: SCT-8 Copyright 10/1996 Specialty Concepts, Inc.
GENERAL DESCRIPTION
The Specialty Concepts Timer (SCT) is a small, low-cost DC timer for the control of outdoor
lights, pumps or other photovoltaic powered DC loads. This timer is designed to sense
darkness at the PV array or via a photo sensor accessory, and then to automatically turn on
lights or other loads. The loads are then allowed to run for an adjustable period of time for up
to 15 hours, or until sunrise, whichever occurs first. The SCT operates in 12 or 24 volt DC
systems and is rated for 8 amps. It is housed in an anodized aluminum chassis and
encapsulated in a hard epoxy resin. The terminal block accepts up to 12 gauge wire or a
spade connector. The SCT is designed to work with the photo sensor accessory or in
conjunction with a photovoltaic system that has a blocking diode located between the battery
and the array. In many systems, a blocking diode is already included within the charge
controller.
)
APPLICATIONS
The SCT is designed as a system component for small to intermediate lighting applications
that require more light than provided by a walkway light. The 8 amp capacity allows one SCT
to control several small (16-30 watt) lights from a centrally located array and battery, or larger
lights can be individually controlled. This allows each lighting system to be custom designed
using a main battery bank or several distributed batteries. The SCT can be used to control an
external relay for higher capacity, or to turn an inverter on for AC systems.
FEATURES
LIGHT TIMER
• 8 amp capacity, 12 and 24 volt
• Turns light on at sundown
• Adjustable run time, up to 15 hours
• Can be used as a day/night switch
• Uses PV array for sundown detection
• Photocell sensor assembly available
(accessory)
DESIGN FEATURES
• Encapsulated for protection
• 100% solid state
• Input noise suppression
• Reverse polarity protection
• Lightning protection
SPECIFICATIONS
PARAMETERS UNITS VALUE
Nominal Voltage (Volts) 12 to 24
Load Current, Continuous, (1) (Amps) 8
Load Current, Max (60 seconds) (2) (Amps) 10.5
Array Voltage, Max Voc (Volts) 44
Operating Voltage @ Battery, Maximum (Volts) 31
Operating Voltage @ Battery, Minimum (Volts) 10.5
Array Voltage to Reset, Minimum (Volts) .5
Quiescent Current Consumption, Day, Typ. (Milliamps) 16
Quiescent Current Consumption, Night,
Load Disconnected (Milliamps) 7
Quiescent Current Consumption, Night,
Load Connected (Milliamps) 7
Voltage Drop, Battery to Load, @ 8 amps (Volts) .4
Adjustable Run Time, Loads, Range (Minutes/Hours) 10 min. to 15 Hrs.
Time Delay, Typ. (3) (Minutes) 15
Operating Temp. Range (°C) -20 to 50
Storage Temp. Range (°C) -55 to 85
Notes:
(1) Non-inductive.
(2) Carry only, Non-switching
(3) Prevents false triggering
PART NUMBERING KEY
SCT - 8
ACCESSORIES
PHOTOCELL SENSOR - Assembly
Model
Nominal Current
Specifications and product availability subject to change without notice.
RELATED SYSTEM EQUIPMENT
The SCT can be an integral part of a solar electric power system that usually includes a solar
panel (or other charging source), a charge controller, a battery and a light or other load. These
items should be installed according to the instructions provided by the equipment supplier, and
this manual assumes that the rest of the equipment installation has been properly completed.
PANELS / CHARGING SOURCES: The SCT is compatible with all makes and models of PV
panels, provided the open circuit voltage of the solar panel (or charging source) does not
exceed 44 volts.
BATTERIES: The standard SCT is designed to be used with lead-acid batteries. Other 12 or 24
volt nominal power sources would be suitable also.
LOADS: The load is considered the item or equipment that the PV system is powering. System
loads such as lights, radios, DC/AC inverters, etc. must be rated for the proper DC input
voltage. The SCT can be used with DC loads not exceeding 8 amps. Higher current, or
inductive loads such as pumps, motors or inverters cannot be switched by the SCT
directly, and should be connected directly to the battery, with a relay controlled by the
timer to provide switching. Properly rated over-current protection devices (fuses or circuit
breakers) should be used.
ACCESSORY - PHOTO CELL SENSOR: For systems that are not photovoltaic powered, or PV
systems that do not have a blocking diode, a photo cell sensor is available to detect night
and start a light or other load.
INSTALLATION
WARNINGS / CAUTIONS
WARNING: Electricity, even low voltage electricity, can be dangerous. Installation should be
performed by a licensed electrical contractor or other qualified personnel only. It is recommended
that the requirements of all applicable local electrical codes (or U.S. National Electrical Code in
the absence of local codes) be followed.
WARNING: Follow all safety precautions of the battery manufacturer and the National Electrical
Code. Proper ventilation must be provided for vented batteries. Most vented batteries produce
hydrogen gas when charging, which is extremely explosive. DO NOT expose the battery to open
flame, matches, cigarettes or sparks.
CAUTION: DO NOT subject the timer to voltages greater than 44 volts. This would be the open
circuit voltage (Voc) of the solar panel, or the sum of the open circuit voltages of all modules
connected in series.
CAUTION: DO NOT exceed the maximum current rating of the SCT, 8 amps, as stated in the
specifications.
TOOLS AND MATERIALS NEEDED:
1 SCT (and possibly the Photo Sensor accessory - see below)
2. Standard screwdriver
3. Wire and wire strippers
4. Drill and appropriate bit: if holes must be drilled in the mounting surface
5. Fasteners to mount unit: Several types are suitable and will depend upon the type of material
of which the wall is made. These are not included with the SCT.
6. Blocking Diode: This may be needed, see below.
7. Small slotted screwdriver: to set run time
8. Stop watch: for accurate run time settings
WHEN A BLOCKING DIODE IS REQUIRED:
A blocking diode is required when the SCT detects sundown by using the solar array (and
not by using the Photo Sensor accessory) Note that the blocking diode is often already
included within the charge controller (such as the ASC controller). In this case, no
additional blocking diode is required.
WHEN THE PHOTO SENSOR ACCESSORY IS REQUIRED:
For systems that are not photovoltaic powered, or PV systems that do not have a blocking
diode, a photo cell sensor is needed to detect night and start a light or other load. The
photo sensor can also be used on systems where the light sensitivity needs to be adjusted.
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