The SCR490D is used to provide remote monitoring of steady burning incandescent marker and obstruction lighting. Four onboard switches allow operator programming for lighting systems with two through nine lamps on a single AC circuit. The SCR490D uses a toroidal sensor and electronic circuitry to sense the failure of one or more lamps. Operation When a lamp fails, the SCR490D senses a decrease in current flow. Then, after a fixed time delay, it transfers to its alarm mode. In alarm mode, the LED indicator, the output relay (SPDT isolated contacts), and a non-isolated solid-state output are energized. Replacement of the failed lamps resets the alarm outputs and the LED indicator. To prevent false alarm signals, power must be applied to the SCR490D at the same time that lamps are energized. Specifications Operation Number of Lamps 2 - 9 (selectable) Lamp Wattage 116W, incandescent lamps Rated Lamp Voltage 120 or 130VAC (selectable) Monitored Voltage 120VAC ±3% Trip Delay ≅ 6s fixed Voltage 120VAC AC Line Frequency 50/60Hz Tolerance 120VAC - 20% - 10% Line Voltage Output (Solid State Rated) ≤ 125W to operate a spare lamp or alarm Isolated Alarm Output 10A @ 120VAC or 30VDC resistive;1/4 hp @ 125VAC; 1/2 hp @ 250VAC Mounting Surface mount with two #6 (M3.5 x 0.6) screws Dimensions H 88.9 mm (3.5”); W 63.5 mm (2.5”);D 44.5 mm (1.75”) Termination Screws with captive clamps for up to 14 AWG (2.45 mm2 ) wire Circuitry Encapsulated Operating/Storage Temperature -55° to 65°C / -55° to 85°C Humidity 95% relative, non-condensing Weight ≅ 6.8 oz (193 g)