Description
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.