ABSTRACT
To expand the range of operational voltage, logic inputs of digital protective relays (DPRs) are often designed to be able to engage at very low (in relation to nominal rating) voltage rates (e.g., 60-80 V at nominal rating of 230 V). In the newest installations, a wide range of acceptable operational voltage rates is divided into several subranges, which can be selected by a consumer depending on specific conditions of use.
