Detecting and monitoring voltage for power quality or safety applications requires isolation between the primary voltage and the voltage detection circuitry. This isolation is required for two purposes: a) To protect the detection circuitry (powered by a source independent of the primary line voltage at less than 50V, and considered non-hazardous), and b) To prevent any possibility of the primary line voltage (typically greater than 50V) from reaching personnel. There are a variety of isolation methods that one can employ for this that include optical, thermal, magnetic field and electric field techniques. This record sketch describes these various techniques and also describes methods to validate the subsequent result generated from each isolation technique to ensure that the result and any subsequent indication is accurate.
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