Carrier 19XRV Phase Reversal

[cvogel]

I have 3 19XRVs in a plant that is 15 years old. 1 of the machines is showing a phase reversal error all of a sudden. I have checked phase sequence, compared CTs and Voltages at ISM. (PIC II machine). All parameters are normal. Machine started having Over Voltage issues; but, raised control level to 490 and that solved issue. Pulled ISM apart and checked all internals. Any advice greatly appreciated. This is the only machine doing it. Thanks in advance.

[maincustom43]

having the same exact issus on a 19xrv- first i got a line voltage inbalance and now am getting a phase reversal that wont clear. if you look at the status for the ism the line voltages are fluctuating and reading way off. eveyrone is telling me the ism board is bad. there is a service bulletin to change the current imbalances to greater than 40%, went o 55% but this hasn't helped - now gettting a high line voltage prestart alert. will keep researching, but probably will end up needing a new ism.