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] [SMTP:[email protected]]
Sent: Tuesday, March 09, 1999 11:26 AM
To: [email protected]; [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]
Visit our Website: http://www.itl.co.il
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