As I recall, the NorPaks are an obsolete line of AC and DC motor drives that Square D produced in the mid to late '70's. The modules you have were used as sensor interface units to monitor motor current by way of current transformers or CT's. The NorPaks are so old that you probably would have to search long and far to even find a SqD employee who remembers them. They were kind of an orphan product even when new. I no longer have my copies of old SqD digests as a reference and there is nothing on the SqD site about them. SqD was bought in the early '90s by Group Schneider, a French company who proceded to dismantle all support for older products. Joe wrote: