I got hold of a large Merlin Gerin Masterpact M16N1 circuit breaker, from 1997, from a low voltage distribution drawout system. In the video you get a inspection of the various parts of the breaker and I have some fun making it work and test it!
It was a deal to get it now or miss it, so I had to transport the damn thing of around 50kg home on my bicycle, good thing I only had to balance it for a 2 km walk. If you want to see a short circuit test at 50,000 Ampere, click here!
Product series data
The Masterpact M series circuit breaker is used to protect and control low voltage distribution systems. It can be installed in main LV switchboards (incoming units, main and secondary outgoers).
Nominal current: 800 to 6300A AC
Breaking capacity from 40 to 150 kA rms
Voltage rating: up to 690 V
Versions: 3 and 4-pole. Fixed or drawout.
The front of the unit had a crank for charging the internal spring, ON/OFF buttons, short-circuit curve settings, indicators and a hidden timer setting PCB. The undervoltage- and remote operation coils can be seen as the two cylindrical parts at the top. Underneath the large and dangerously powerful spring can be seen. This version also has a motor assisted charging mechanism, that can be used for remote closing of the breaker.
Inside the switching chamber where the arc suppressor mounts down into. The 10 copper arms that can be seen are not the main contact points. These are silvery and can be seen lower down and fits with the 10 dark square marks. Those can be seen in the wear-surface of the output terminal. One of the Arc suppressors/chimneys are also shown.
I could not find a manual for this rather old unit. I had to find some manuals from the more modern versions and it did share the same schematics. The hidden timer settings PCB is a configuration of the maximum permissible time between undervoltage coil activation (MN) and closing release (XF) activation. If this time is passed, the breaker will not close. I need some other conditions to keep it closed. But for the tests I want to do, a closing and opening with a 3 second time is perfect!