text: <s>[INST] VFD Clearance issues Summary: Powerflex 520 - Clearance IssuesAll, We are having a little debate at work on VFD clearances. and adhering to the specifications. The question is simple, I just cant find the answer. In the specifications for the Powerflex 520 Series AC Drive, you will find a section on Clearance. It shows different mounting options for Vertical and Horizontal. There are 4 scenarios for mounting vertical when you have more than one VFD, but I am only concerned with two of them 1) Vertical Mount - Keep 1 inch in between. 2) Vertical, Zero Stacking - No clearance in between. My question is, what is Zero Stacking? Is that meaning having two rows of VFD's? That's what I get out of it. Others at work disagree and think the Stacking implies the VFD mounted next to it. I think stacking means having two or more ROWS of VFD's. Co-workers think stacking as a side-by-side VFD mounting. Thoughts anyone? [/INST] It looks like zero stacking simply means when you mount the VFD next to each other with no (zero) space between them. I didn't find anything mentioning having multiple rows of VFDs. In some VFDs this can de-rate the max ambient operating temp. In others, it doesn't affect the max operating temp. Frames 0-6 do not need to be de-rated (see below language from spec sheet). • Zero Stacking™ – Frame 0…6 drives can be mounted next to each other with no reduction of surrounding air temperature rating (50 °C). This unique bookshelf design also allows access to one drive without disturbing another. In general, it looks like zero stacking derates the operating temp by 5 deg C. \\n </s>