Abstract: A DC-to-DC converter includes one or more power switches, a pulse width modulation circuit for generating control pulses for the power switches, and an output inductor connected to the power switches. A thermally compensated current sensor is connected to an intrinsic current sensing element exhibiting a temperature-based parameter non-linearity. The thermally compensated current sensor has a temperature coefficient that substantially matches a temperature coefficient of an intrinsic power converter element used to measure current flow, thus linearizing the current measurement. Also, a current feedback loop circuit cooperates with the pulse width modulation circuit to control the power switches responsive to the thermally compensated current sensor.

Abstract: A method of calibrating the selectable trip points of an overload relay wherein a neural network is used in the calibration process. The calibration method involves precisely positioning an indicia comprised of a number of graduation marks or symbols each representing a particular trip point and having a range and spacing unique to the characteristics of an overload detection circuit of a particular overload relay. The indicia is calibrated with respect to predetermined positions of a trip point indicator and fixed with respect to the predetermined positions of the trip point indicator. The range and spacing of the indicia graduations is derived from the neural networks learned trip point values and from trip point values obtained from the particular overload relay being calibrated.

Abstract: Impedance of an energized electrical line which carries electrical current at a predetermined line frequency is nondistruptively measured at frequencies which are above and below the predetermined line frequency. A measurement current is generated at a measurement frequency between, for example, 10 Hz and 30 kHz for a 60 Hz line. The current generator is coupled to the energized electrical line by an isolating circuit which blocks only the predetermined line frequency and frequencies which differ from the predetermined line frequency by substantially less than the predetermined line frequency. For example, a notch filter may be used. A current sensor measures the line current in the energized line at the measurement frequency. A voltage sensor measures the line voltage in the energized electrical line at the measurement frequency. An analyzer determines impedance of the energized line at the measurement frequency. The measurement is repeated over a wide range of frequencies above and below the line frequency.