ABB ACS380 Hardware Manual page 99

Technical data 99
4) 480Y/277V delta systems only: Short-circuit protective devices with slash voltage ratings (e.g.
480Y/277 V AC) can be applied only in solidly grounded networks where the voltage from line-to-ground does
not exceed the lower of the two ratings (e.g. 277 V AC), and the voltage from line-to-line does not exceed the
higher of the two ratings (e.g. 480 V AC). The lower rating represents the device's interrupting capability per
pole.
5) For all drives, the enclosure must be sized to accommodate the specific thermal considerations of the
application as well as provide free space for cooling. See section Free space requirements on page 101. For
UL only: The minimum enclosure volume is specified in the UL listing when applied with the ABB Type E MMP
shown in the table. ACS380 drives are intended to be mounted in an enclosure, unless a NEMA-1 kit is added.