Abstract: A power circuit for N series connected loads according to the present invention includes N transformers having primary windings connected in series across a constant current AC source and secondary windings connected in series with the N loads. N-1 conductors are coupled from a junction between the loads to a corresponding junction between the secondary windings. Failure of one of the loads resulting in an open circuit will not interrupt power to the remaining loads.

Abstract: A runway approach lighting system with fault monitor includes an oscillator which develops clock pulses which are accumulated by a counter. The output of the counter is used to develop trigger signals which control the sequential energization of runway alignment indicator lights. The operation of each light is sensed and is compared with the oscillator pulses, and a fault signal is generated each time a light fails to operate in response to a trigger signal. The number of fault signals generated in an energization cycle is accumulated, and a fault indication is generated once a predetermined number of faults has occurred.