The RCS-II (RCS-2) is an electronic 79 relay which was used in new manufacture and as a replacement for the original RCS relay. It has an unusual physical form factor. As such, no direct replacement was ever built by Basler or even ABB. To replace with an aftermarket relay requires an outage and extensive panel cutting. A rebuild is a much more cost effective route for a breaker which may be nearing it’s rebuild/replace cycle, but hasn’t quite yet reached that point in the budget cycle. Since most utilities have few, if any spares on hand for these, we treat these to “front of the line” service priority.