The SCR490D Series 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.

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.

• Senses Failed Obstruction Lamps
• 2 - 9 Steadily Burning Lamps can be Monitored
• Toroidal Current Sensing
• 10 A Isolated SPDT Alarm Output Contacts
• 1 A Solid State Line Voltage Alarm Output
• Six Second Trip Delay Prevents Nuisance Alarms