EPROM-based overcurrent relays

A very simple and inexpensive time-overcurrent relay is reported. The relay is implemented using EPROM, a binary counter, a digital to analog converter, an analog comparator, and logic gates. As an extension of the work, the implementation of a multicurve time-overcurrent relay is reported. The switching of only four relays has been considered in this implementation. If required, the implementation can be expanded to accommodate more curves by increasing the EPROM memory area and the associated hardware. The system can be converted to handle multiple independent overcurrent relays by providing more comparators and associated control logic.<>