Just a quick note to follow-up with Richards comments. If the power supply
is recognized you will also want to make certain you get the conditions of
acceptability. It is not uncommon for power supply manufacturers to run the
tests with some CFM of air blowing across the supply, especially if they
aren't providing a fan as part of the supply. You'll want to note that and
to determine if you can prove that in your end use there will be that amount
of air flowing across the supply - not just into the cabinet but actually
across the supply.
Gary
-----Original Message-----
From: WOODS, RICHARD [mailto:[email protected]]
Sent: Tuesday, March 09, 1999 11:15 AM
To: [email protected]; [email protected]
Subject: RE: Rack System Safety (UL1950/EN 60950)
Questions
1. Peter, equipment with the standard NEMA plug is
considered to be Class A..
2. Equipment using the heavy duty Industrial plugs
complying with IEC are considered to be Class B. I have never seen those
used inside rack mounted equipment.
3. If the power supply is UL "Listed", then temperature measurements
are not required. However, most power supplies are categorized as
"Recognized" and are therefore incomplete in construction - that is, they
cannot pass the safety requirements for a stand alone power supply.
Temperature measurements will be required.
4. Stability is performed in a worst case situation, but reason is also
taken into account. Most likely, you will determine that it is possible and
reasonable to assume that more than one assembly can be extending at the
same time.
5. UL requires that all internal equipment be UL Listed
or Recognized.
---
From: [email protected] <mailto:[email protected]>
[SMTP:[email protected]] <mailto:[SMTP:[email protected]]>
Sent: Tuesday, March 09, 1999 11:26 AM
To: [email protected];
<mailto:[email protected];> [email protected]
<mailto:[email protected]>
Subject: Rack System Safety (UL1950/EN 60950)
Questions
Dear All,
I would like to know some of your professional advice on
some issues reagrding rack systems to be evaluated to UL1950/EN 60 950.
1. For the North America, does a NEMA 125 V, 20 A plug meet
the pluggable B definition?
2. What are some plug configurations which will meet the
pluggable B equipment requirements for North America and Europe?
3. Does anyone have experience with UL and/or CSA and/or
TUV when testing a unit employing a Recognized/Certified/Approved computer
type "totally enclosed" power supply? I am interested to know if
temperatures should be monitored within such a power supply. So far, I have
been asked to thermocouple various points within the power supply and as you
all know, it could get very crowded in there. I am interested to know if
someone out there knows if such a waiver exists for totally enclosed
Approved power supplies.
4. When conducting stability tests for rack systems, should
all the serviceable card cages be extended out or is it enough to do it one
at a time.
5. For a CSA NRTLC unit employed in the rack system, does
anyone know if the CSA NRTLC Mark is automatically accepted by UL or does UL
require that the unit must be re-investigated and placed under their
Follow-Up Program?
6. Has the US Robotics Listed "Sporster" card modem been
evaluated to UL1950 Third Edition?
7. Can I List/Certify a rack system to UL1950 Third Edition
if the units within it have been Listed/Certified to UL1950 First and/or
Second Editions? I do not think so, but am interested to hear your opinions.
8. How is a CB test report done for a rack system which
consists of previously Listed/Certified/Approved units? Does the CB scheme
Recognize the Approvals of the various test agencies (UL/CSA/TUV)?
Thanks in advance.
PETER S. MERGUERIAN
MANAGING DIRECTOR
PRODUCT TESTING DIVISION
I.T.L. (PRODUCT TESTING) LTD.
HACHAROSHET 26, P.O.B. 211
OR YEHUDA 60251, ISRAEL
TEL: 972-3-5339022
FAX: 972-3-5339019
E-MAIL: [email protected] <mailto:[email protected]>
Visit our Website: http://www.itl.co.il
<http://www.itl.co.il>
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