LOW-COST, FULL-RANGE ELECTRONC OVERLOAD RELAY DEVICE

An electronic overload relay leverages a ratio metric current design to permit size and cost optimized circuit components that can be used to sense current for purposes of protecting motors by detecting overcurrent conditions in branch motor applications in lieu of thermal overload devices. A current divider is used to significantly reduce the current that must be sensed by a magnetically coupled toroid to permit its components to be size and cost optimized and to be implemented easily on a printed circuit board. The DC resistance can be used to provide a coarse design that can be calibrated pre-manufacture to establish the accuracy required in sensing motor load current by adjusting the value of the burden resistor. Precision printed circuit board traces can be used to ensure repeatability during manufacturing. A sweepable trigger value generator can permit operation over the entire range of FLC and the threshold can be calibrated into the device.