简单介绍
The motor protection relay MRM3-2 offers reliable protection for LV and MV motors which are ei-
ther 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.