Method for detecting a series resistance fault in a digital-electricity transmission system

A method for detecting a series resistance fault, comprising:

• a) in a digital-electricity power system, comprising (i) at least one transmitter including transmitter terminals and (ii) transmission lines in electrical contact with the transmitter terminals, using at least one controller to monitor and control voltage on at least one of the transmission lines and to interact with at least one receiver including receiver terminals in electrical contact with the transmission lines;
• b) acquiring at least two sample values indicative of line-to-line voltage at the receiver terminals, wherein at least one of the voltage sample values are acquired while electrical current is flowing in at least one of the transmission lines, wherein the acquisitions of the voltage sample values are separated by a time period, and non-transitorily storing the voltage sample values in computer-readable memory accessible by a controller of the at least one controller;
• c) acquiring sample values indicative of electrical current in at least one of the transmission lines, wherein each electrical-current sample value is taken along with at least one of the voltage measurements within a time window over which the current and voltage at sites on the transmission lines where the sample values are acquired are substantially unchanged for each set of electrical-current sample values and line-to-line voltage sample values, and non-transitorily storing the electrical-current sample value in computer-readable memory accessible by the controller of step (b);
• d) analyzing the stored electrical-current sample values to identify a change in the electrical-current sample values over at least one of the time periods that exceeds a predetermined minimum and storing the change in the electrical-current sample values and the corresponding change in the voltage sample values over the same time period;
• e) dividing the change in the voltage sample values by the change in the electrical-current sample values to calculate a value indicative of transmission-line series resistance, wherein the calculation is valid provided that line-to-line voltage at the transmitter terminals remained substantially constant during the time of measurements of the voltage sample values and the electrical-current sample values;
• and
• f) comparing the series resistance value to a predetermined maximum, wherein exceeding the predetermined maximum is indicative of a series resistance fault, and acting to provide a voltage and/or current of approximately zero or at a value safe for human contact and fire prevention when the series resistance exceeds the predetermined maximum.