17 years ago
I am looking at building a change over panel to change over between 4
different 240v 1 phase AC supplies on a barge - 3 supplies are max 20A
(shore, alternator and inverter) and the fourth is max 48 Amp
Had looked at using control relays with 2 NO and 2NC poles but have
been advised that they are not suitable for changing over between 2
different power supplies as the change over is very short and there is
no mechanical interlock.
Now looking at using power contactors and reckon way ahead is to use 3
pole NO contactors in pairs, using only 2 of the poles, and a
mechanical interlock in each pair to prevent connecting 2 power
sources at the same time. As I understand it with the mechanical
interlock, when contactor A is made, contactor B cannot close even
with its coil energised until contactor A is de energised and the
Some of the conatctors need 240v AC coils and some 24v DC coils, but
this does not seem to be a problem.
Have RCDs etc downstream in the fuse panel.
Grateful for any thoughts.