MRM3-2 – Motor Protection Relay

The motor protection relay MRM3-2 offers reliable protection for LV and MV motors which are either operated via power contactors or power circuit breakers. The following functions are integrated into this relay: • Overload protection acc. to IEC 255-8 in consideration of the initial load factor (thermal image) • Definite undercurrent protection • Definite time over current protection (DMT) • Inverse time over current protection (IMT) with select-able trip characteristics • Short-circuit protection • Load unbalance supervision with definite or inverse trip characteristics • Earth-fault detection with suppression of harmonics The MRM3-2 recognizes the “Start-Up“ and “Motor Running“ phase. Motors with a limited number of starts can be controlled by the start limiting function of the relay. The earth-fault supervision is either realized in Holm-green connection or by means of a core-type current transformer. The motor can be stopped in delayed or undelayed mode via digital inputs. The MRM3-2 is available with rated currents of 1A or 5A. Important: For additional common data of all MR-relays please refer to manual "MR - Digital Multifunctional relays". On page 45 of this manual you can find the valid software versions.

FEATURES & FUNCTIONALITY

The motor protection relay MRM3-2 offers reliable protection for LV and MV motors which are either operated via power contactors or power circuit breakers. The following functions are integrated into this relay: • Overload protection acc. to IEC 255-8 in consideration of the initial load factor (thermal image) • Definite undercurrent protection • Definite time over current protection (DMT) • Inverse time over current protection (IMT) with select-able trip characteristics • Short-circuit protection • Load unbalance supervision with definite or inverse trip characteristics • Earth-fault detection with suppression of harmonics The MRM3-2 recognizes the “Start-Up“ and “Motor Running“ phase. Motors with a limited number of starts can be controlled by the start limiting function of the relay. The earth-fault supervision is either realized in Holm-green connection or by means of a core-type current transformer. The motor can be stopped in delayed or undelayed mode via digital inputs. The MRM3-2 is available with rated currents of 1A or 5A. Important: For additional common data of all MR-relays please refer to manual "MR - Digital Multifunctional relays". On page 45 of this manual you can find the valid software versions.