Brief history of the unit. Couple of months back at a local university an Ice machine was installed. Electrical storm popped up and fried the board on this unit. 0 ohms between L1 and L2. Tech support said change out the board under warranty. Head honco onsite told his maintenance guys to install some sort of surge protection to prevent this from happening again.
Two weeks later, another storm and another board fried. This time they ate the cost of the board and replacement and installed a supco scm150 surge arrester on the panel box. New board comes in and installed and everybody is happy.
Last Thursday another storm came by poof! Another board. I went out there today already having an idea what it was. Isolated the board, replaced the fuse, restored power and same thing, the board is gone. I spoke with Bert at mani tech support, great guy btw, and he said that only a high voltage spike can fry a board. If a component fails, dump valve, inlet valve, hgv solonoid valve shorts out that the fuse will blow and thats it, The board should not be damaged in anyway. He did warranty that board too.
I checked the wiring of the supco scm150 and it is wired in parallel on the outlet of the 20 amp breaker going to the unit. The ground it wired to the bus bar. Voltage at the outlet is 242 volts with each leg within a tenth of a volt to each other. From what I read on supco's pdf file is that this surge arrester works by shunting power to ground in the event of a power surge.
I spoke to the head maintenance guy to have his electrician look at the panel box again and to recheck the wiring of the surge arrester to verify that it is wired correctly and to verify that the ground was hooked up properly. I was offsite at the time and unable to check myself.
Has anyone come across this problem and how were you able to correctly address the situation so it would not happen again.
Thanks again for any input.