Reduced Voltage Soft Starter NEMA Size?

[FaradayFF]

Hello Folks,
Does a RVSS get a NEMA size, or is NEMA size only applicable to full voltage starters? I got an MCC submittal, and vendor is not specifying NEMA size rating for RVSS starter type. Figured that RVSS is based more on a particular vendor model & amperage.
Thanks,
EE

 

[jim dungar]

Solid state reduced voltage do not have NEMA ratings.
Wye-Delta and Auto Transformer styles do have NEMA ratings.


Does anyone generally purchase new units other than these styles?

 

[garbo]

Side note: After I told our drive salesperson that I needed a replacement drive for a 100 HP 480 volt three phase two or four pole plain Jane NEMA frame motor halve a dozen different times would tell me they are not rated for horse power but rather ampere. Finally it was easier to send him a picture of the 26 or 28 character serial # that I was replacing. Told him that these motors draw 124 amps. Replacement drive would be rated for 125 amps but on box label usually gave a HP rating. I know there are old odd ball motors out that do have higher FLA on motor nameplate that could require next higher HP drive. Appears the RVSS follows suit. We had a RVSS on a 250 HP fire pump In third level ( lowest ) basement that was never above 70 degrees . When I performed a monthly & yearly PM on it liked to run it for maybe two minutes then shut it down to check pump packing then restart it. Using a quality FLIR camera was surprised that at best temperature on RVSS only increased one degree F.

 

[kwired]

Side note: After I told our drive salesperson that I needed a replacement drive for a 100 HP 480 volt three phase two or four pole plain Jane NEMA frame motor halve a dozen different times would tell me they are not rated for horse power but rather ampere. Finally it was easier to send him a picture of the 26 or 28 character serial # that I was replacing. Told him that these motors draw 124 amps. Replacement drive would be rated for 125 amps but on box label usually gave a HP rating. I know there are old odd ball motors out that do have higher FLA on motor nameplate that could require next higher HP drive. Appears the RVSS follows suit. We had a RVSS on a 250 HP fire pump In third level ( lowest ) basement that was never above 70 degrees . When I performed a monthly & yearly PM on it liked to run it for maybe two minutes then shut it down to check pump packing then restart it. Using a quality FLIR camera was surprised that at best temperature on RVSS only increased one degree F.

That has been my observation with both VFD's and electronic soft starters - ampere rated. And depending on usage conditions you may need to derate the unit if there is frequent starting or reversing or even for starting a high inertia load. The drives will have a utilization voltage or somewhat narrow range of utilization voltage but soft starters are often 600 volt rated but anything below that is fine as well.