Ok thank you. Sounds good
Lastly, is an MCP (Motor ckt protector) only sufficient for protection of the VFD or do I need to install a thermal-mag ckt. bkr in there?
Replace it. There is NO legal use for an MCP outside of a factory assembled combination motor starter. They cannot be used as a feeder in any way, shape or form.
It used to be, a few years ago, that a manufacturer could use an MCP on a factory built VFD or Soft Starter, that is no longer the case, UL started disallowing that in about 2005.
Very lastly, regarding enclosure for the vfd drives... (these are in mech. room, uncovered to elements). Nema 4x cabinet with enough space for the VFD's and controls, unistrut anchored to cmu wall?
Thanks
The VFD rejects about 3% of the power going through it as heat, so if you seal it up in a NEMA 4 box, it can cook itself pretty fast. If it's small, I have been able to get away without venting by taking the volume of a manufacturer's NEMA 1 enclosed drive and quadrupling it. So for example if a NEMA 1 drive is 10 x 8 x 14, that's 1120 cu. inches, so I use a sealed enclosure that is at least 4480 cu. inches. But this is dependent on the environment being relatively cool, as in at least 25deg.F less than the max rating of the VFD. So if the VFD is rated for 40C, that's 104F so your environment needs to be no more than 79-80F consistently, in other words an air conditioned space. If the area where you want to put the drive gets to 100F, the drive will cook itself no matter what and you will need an A/C or a lot of ventilation. Some drives however come with an option to shove the heat sinks out of the back of the box, that takes 90% of the heat out of it. If your drives have that option, do that.