Technical FAQs

# How is the ATS48 softstart sized for higher elevation use?

Issue:
How is the ATS48 softstart sized for higher elevation use?

Product Line:
Altistart ATS48

Environment:
All

Cause:
Derating for high altitude

Resolution:
Maximum operating altitude is 3300 feet without derating. Above this, the softstart will need to be derated by by 2.2% for each additional 330 feet to the maximum of 6600 feet based upon softstart current rating.

Example:
40HP 460VAC Soft Starter is normally an ATS48D62Y however if you are going to use this unit at 6000 ft you will need to up size by 1 or more. So you will need to use a
ATS48D75Y for a 40HP 480VAC.
3300 feet is basic rating without derating.
6000 feet - 3300 feet = 2700 feet.
Derate by 2.2% each 330 additional feet.
2700 ft / 330 ft = 8.1818 X 2.2%= 18% current derate of the product.
Soft Starter is rated for 75 amps X 18%= derate of 13.5 amps
or 75amps minus 13.5 amps = 61.5 amps
ATS48D75Y now only rated for 61.5 amps not 75 amps.

Derating Drives operating at 6000 ft will be as follows.
62 amp ATS48D62Y is rated for only 51 amps.