TCL/DOT LED Blank-out Sign in IP55/NEMA 3X Cabinet
Construction and Operation
- Frame Housing
- Slim line, single piece of extruded aluminum (6063-T5), that houses the polycarbonate, circuit board as well as the sign back.
- The extruded aluminum consists of a 2.5" depth.
- The length of the extrusion varies for each sign size customization.
- The corrosion resistant aluminum bends to the sign size and each end is secured together by an extrusion and screws.
- All components shall be placed to avoid drip points.
- All wiring shall incorporate drip loops and strain relief
- The cabinet shall have an electrostatically applied Duracon 5600RTS Heritage Bronze coating.
- The finish shall meet the following criteria:
- 16-22% Gloss @ 60°
- H-2H Pencil Hardness
- Dry film thickness 1 - 1.2 mils
- The back of the sign is .125 aluminum
- At the top of the back, there is a lip that is inserted into the extrusion.
- At the bottom of the back, there are two screw holes which secure the back to the extrusion.
- Standard wall mount included.
- Front frame shall consist of a 0.125" tinted polycarbonate protective face.
- The polycarbonate shall contain UV inhibitors to protect the circuit board from the effects of ultraviolet light and prevent the premature aging of the polycarbonate face.
- The polycarbonate face shall have the following characteristics:
0.5 lb No Break
100x material thickness
Thermal Expansion Rate
3.75 x 105 in/in ºF
0.25" clear sheet
LED Circuit Boards
- LED circuit boards shall be manufactured using an FR-4 laminated fiberglass/epoxy printed circuit board with the front face printed with black UV cure ink or black paint.
- The failure of an LED string shall not cause the failure of any other LED string.
- The circular base of the discrete LEDs shall be soldered such that they are flush.
- Exposed traces, vias, and solder joints on the LED circuit board, with the exception of connector contacts and terminals, shall be protected from water and humidity by application of conformal coating.
- The conformal coating shall contain a UV brightener to aid in visual inspection.
- The presence of ambient radio signals, magnetic interference, and electromagnetic interference shall not impair the performance of the sign system. Interference includes power lines, transformers, and motors. The sign will not radiate electromagnetic signals that adversely affect any other electronic devices, including those located in vehicles passing underneath or near the sign and its’ controller.
- The Cabinet and sign components shall operate in the following temperature and humidity conditions:
Operational temperature range: -30°F to +165°F
- Humidity range: 0% to 99% (non-condensing)
- Storage temperature range: -40°F to +165°F
- Components will not be damaged by a temporary exposure while operating to a temperature range of -40°F to +185°F
- Discrete LEDs
- The discrete LEDs shall be driven at a current level that is in accordance with their operating environment. Signs will use voltage pulse width modulation (PWM) to achieve the proper LED intensity level for ambient light conditions. The drive pulse shall be modulated at a frequency high enough to provide flicker-free operation.
- The LED drive circuit board shall contain a microcontroller regulation circuit that controls the PWM duty cycle.
- LED Specifications
Min Brightness (mcd)
x= 0.31 y= 0.32
- Regulated DC Power Supplies
- The LED Circuit board shall be powered with auto-ranging regulated switching power supply that converts the incoming AC electricity to DC, at a nominal voltage of 12VDC.
- Power supplied shall be UL recognized.
- Power supplies shall be arranged in a redundant parallel configuration, and rated such that if one supply fails the remaining supply shall be able to operate 100% of the LEDs in the sign message.
- The pair of power supplies shall contain two physically and electrically independent supplies. The pair of power supplies shall be placed in parallel according to the manufacturer’s recommendations.
- Power supplies used to power the LED sign message and its controller board shall be identical and interchangeable.
- Power Supply Specifications:
- Nominal output voltage: 12 VDC ±10%
- Operating temperature range for 100% output power: -30°F to +140°F
- Operating input voltage range: 85 VAC to 264 VAC
- Typical power supply efficiency: 81%
- Minimum power factor rating: 0.93
- The power supply shall not be taxed beyond 65% of its rated maximum rated output.
- Power supply input circuit shall be fused.
- Automatic output shutdown and restart if the power supply experiences any of the following output faults: over-voltage, short circuit, or over-current.
Wiring and Power Distribution
- Internal Wiring
- Wiring for the sign components shall be installed in a neat and professional manner. Wiring shall not impede the removal of power supplies or other sign components.
- Wires shall not make contact with, nor bend around sharp metal edges. All wiring shall conform to the National Electric Code
- All internal wiring shall use drip loops.
- Earth Grounding
- Cabinet shall have one earth ground lug that is electrically bonded to the sign cabinet. All earth grounding shall conform to the National Electrical Code.
Environmental Monitoring System
- Ambient Light Measurement
- Sensors that measure the outdoor ambient light level at the site shall be mounted directly to the LED circuit board.
- Three photocell sensors shall be placed such that they measure the ambient light striking the front face. The sign controller shall continuously monitor the light sensors and adjust the LED light intensity to a level that creates a legible message on the face.
- Photocell sensors shall operate in a redundant manner such that if one sensor fails, the remaining light sensors shall continue to adjust the LED light intensity to create a legible message on the face.
- The LED automatic dimming functionality shall continue normally with only a single functioning sensor remaining.