The Littelfuse/SSAC SCR series are Tower and Obstruction Lighting Controls used in a variety of applications. The SCR430T and SCR630T are universal lamp alarm relays designed to sense the failure of flashing or steady incandescent beacon lamps or steady side lights. The SCR9L is a universal lamp alarm relay designed to sense the failure of flashing or steady LED beacon lamps or obstruction lamps. 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.