Paul,
UL 478 had a Starting Current Test in it, which was used to verify
that start-up currents would not cause nuisance tripping of the
overcurrent protective device. The main offenders tended to be
devices with large motors. I believe you can still get UL to evaluate
a product to 478 if you want to until 4/1/2000.
The March 1988 IAC meeting report indicated that the intent of UL 478
clause 28.1 and 28.3 is implied in clause 1.7.2 of IEC 950, therefore
the test method was not added to UL 1950.
Kendall Wilcox
[email protected]
______________________________ Reply Separator _________________________________
Subject: Surge currents when powering up equipment..
Author: Paul Herrick <[email protected]> at SMTP-MAIL
List-Post: [email protected]
Date: 4/22/97 9:09 PM
-- [ From: Paul Herrick * EMC.Ver #2.3 ] --
Does anyone know of any regulatory reason to control the startup surge current
to ITE units? We have measured this startup current to be up to 90A for the
first half cycle of applied voltage. The unit is cord set connected and uses
four switching power supplies and has a rating of 100-120/220-240V 7/3.5A.
Do safety agencies (UL/CSA/TUV) ever measure this start up current as part of a
certification investigation?
++
Thanks,
Paul Herrick
[email protected]
