Is it possible to fit new design MCH to old NW Breaker.
The MCH are fully compatible.
In new MCH , the MCH coupling profile on the axis of the CB changed to facilitate its adjustment from "triangular" to "circular".
To proceed with the adaptation of a spare MCH in a Masterpact it´s necesary to follow the directions of the MCH instruction Sheet.
In the attached document (Spanish language) the most important points are given for correct adjustment:
1st CB in Open position (OFF) and with discharged springs
2nd MCH Profile faced with the notch (see doc)
3rd To facilitate engagement we can slightly rotate the MCH.