Abstract: A monitoring system for monitoring individual modules includes a central station and a plurality of remote modules connected to said central station by a data channel. Each remote module includes a switch responsive to a fault condition for connecting a passive circuit to said data channel. The central station supplies a monitor signal to which the passive circuit is responsive to supply a fault signal. The central station includes a monitor responsive to the fault signal for impressing an interrogation signal onto the data channel to which the passive circuit is responsive to supply a coded signal indicative of the particular module responding to the fault condition.

Abstract: Apparatus for computing an approximation of a running average of the peak voltage of an AC power wave. If this average drops below a predetermined level a brownout signal indicating potential failure of electronic units powered by the AC wave is generated.

Abstract: Apparatus for testing distortion of an AC power wave and providing an error signal if distortion of the type likely to cause DC output of a power supply receiving the AC power wave to fall below acceptable levels occurs.

Abstract: A circuit receiving a varying waveform and providing a plurality of signals, each signal changing when the waveform crosses a predetermined voltage level associated with that signal.