Peter, Responses are below each question. (NOTE: The answers to these questions are easily found in the UL 1950 3rd ed. standard).
>-----Original Message----- >From: pe...@itl.co.il [mailto:pe...@itl.co.il] >Sent: Tuesday, March 09, 1999 11:26 AM >To: emc-p...@majordomo.ieee.org; t...@world.std.com >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? Answer: As per UL1950 3rd Ed/CAN CSA C22.2 No.950 the answer is maybe. If you are just talking a NEMA 5-20P then it is pluggable equipment A. That is - non-industrial. If you use a NEMA L5-20P ('L' for locking or more commonly refered to as 'Twist-Lock') then the answer is Yes. Pluggable equipment Type B requires an 'industrial type plug or appliance coupler. >2. What are some plug configurations which will meet the >pluggable B equipment requirements for North America and >Europe? Answer: Quote from UL1950 "Equipment iwhich is intended for connection to the building power supply wiring via an industrial plug and socket-outlet or an appliance coupler, or both, complying with IEC 309 or with national standards for similar applications. >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. Answer: If said unit is located WITHIN YOUR enclosed product, you still need to take temperature measurements. This is because since it is enclosed in your product, you could increase the ambient temperature of the power supply. Your product will be tested with all openings closed to determine if the internal temperatures of the pwoer supply exceed that allowed temperature rises. You are affecting the power supply's environment. The power supply was originally tested in free air, now you are enclosing it in your unit. >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. Answer: All the drawers could be extended out. They check the unit in its "most unfavorable condition". >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? Answer: The unit will not typically have to be re-investigated. If there is cause for concern, they may require a temperature evaluation. >6. Has the US Robotics Listed "Sporster" card modem been >evaluated to UL1950 Third Edition? Answer: Call US Robotics. >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. Answer: I believe you can do this. "After April 1, 2000 products that were previously evaluated by UL to the requirements in other existing standards (like 1st/second ed.) may continue to be approved until April 1, 2005 without further investigation, provided no significant changes or revisions are made to such products". >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)? Answer: I can't answer this one. Anyone else?? John A. Juhasz Product Qualification & Compliance Engr. Fiber Options, Inc. 80 Orville Dr. Suite 102 Bohemia, NY 11716 USA Tel: 516-567-8320 ext. 24 Fax: 516-567-8322 --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
