VLT 5352-5552, VLT 6042-6602, VLT 8452-8652 - Danfoss For use with frequency converters manufactured between calendar week 5/2010 and calendar week 16/2016. Frequency converters. A 176F2153 conversion kit is required on frequency converters manufactured prior to CW 5/2010, but it cannot be used on frequency converters manufactured after manufactured after calendar week 16/2016.