The difference between the under-voltage coils MN , MNx and MNs of NG125 MCB is given below

MN
- undervoltage release
- tripping and opening of the associated circuit-breaker: if the supply voltage drops between 70 and 35 %
- reclosing: forbidden if the supply voltage is not restored (e.g.: emergency breaking by pushbutton)

MNs
- delayed undervoltage release
- allows a 0,25-second time delay on brownout or voltage drop

MNx
- undervoltage release unaffected by power cuts.