The MRl3 digital multifunctional relay is a universal time overcurrent and earth fault protection device intended for use in medium-voltage systems, either with an isolated/compensated neutral point or for networks with a solidly earthed/resistance-earthed neutral point. The protective functions of MRI3 which are implemented in only one device are summarized as follows: Independent (Definite) time overcurrent relay, inverse time overcurrent relay with selectable characteristics, integrated determination of fault direction for application to doubly infeeded lines or meshed systems, two-element (low and high set) earth fault protection with definite or inverse time characteristics, integrated determination of earth fault direction for application to power system networks with isolated or arc suppressing coil (Peterson coil) neutral earthing. (ER/XR-relay type), integrated determination of earth short-circuit fault direction in systems with solidly-earthed neutral point or in resistance-earthed systems (SR-relay type). Furthermore, the relay MRI3 can be employed as a back-up protection for distance and differential protective relays. A similar, but simplified version of overcurrent relay IRI1 with reduced functions without display and serial interface is also available.
FEATURES & FUNCTIONALITY
The MRl3 digital multifunctional relay is a universal time overcurrent and earth fault protection device intended for use in medium-voltage systems, either with an isolated/compensated neutral point or for networks with a solidly earthed/resistance-earthed neutral point. The protective functions of MRI3 which are implemented in only one device are summarized as follows: Independent (Definite) time overcurrent relay, inverse time overcurrent relay with selectable characteristics, integrated determination of fault direction for application to doubly infeeded lines or meshed systems, two-element (low and high set) earth fault protection with definite or inverse time characteristics, integrated determination of earth fault direction for application to power system networks with isolated or arc suppressing coil (Peterson coil) neutral earthing. (ER/XR-relay type), integrated determination of earth short-circuit fault direction in systems with solidly-earthed neutral point or in resistance-earthed systems (SR-relay type). Furthermore, the relay MRI3 can be employed as a back-up protection for distance and differential protective relays. A similar, but simplified version of overcurrent relay IRI1 with reduced functions without display and serial interface is also available.