Thread Starter


Joined Sep 29, 2022
Hi, I work for company in the UK as an electrical engineer. I have just started at my new place and they have a 3-phase pump motor controller that needs replacing. It's a Coelbo Onematic controller, working off the pressure in the water line. I have a new controller unit but don't want to wire it in and damage the new one. From inspection of the old unit, the main PCB had 3 varistors blown. Their number is 14N431K, 14mm in diameter. I'm hoping to replace these varistors so we have a spare unit but I'm struggling to find the exact parts. Would also be helpful to know why this has happened and if it's likely to happen again, what I can do to prevent it. I'm away that they have likely blown due to a voltage surge but I can't see why this would have happened. Any advice or info would be greatly appreciated!