Abstract: A system for determining whether or not an amount of energy in excess of a pecified minimum amount of energy is stored in a capacitor of unknown capacitance includes a capacitive reference device for storing an amount of energy which is known to be no less than the specified minimum. The system further includes a capacitive calibration device selectively coupled to the capacitive reference device and to the unknown capacitor for providing a first voltage when coupled to the capacitive reference device, and for providing a second voltage when coupled to the unknown capacitor. A comparator device which is calibrated by the first voltage receives the second voltage and provides an indication signal when the unknown capacitor has stored an amount of energy which exceeds the reference amount of energy.

Abstract: Apparatus for selectively measuring voltage, resistance, and time duration f an event, each of which is associated with an electrical network, includes a device for providing a first train of digital pulses, the frequency of the pulse train being related to an analog voltage coupled thereto. The measuring apparatus also includes a clock for generating a second train of digital pulses of fixed frequency, and a constant current source to be coupled to a resistive element being measured by the apparatus. The apparatus further includes counters selectively receiving one of the digital pulse trains for counting the number of pulses received during a selected time period, and for providing a digital output in which the value of a quantity measured by the apparatus is encoded.