RE: Are all these agencies really necessary?
Dan, You are absolutely correct in questioning the need to get certifications from all those agencies. All of the product safety reports that I have for our products are basically the same report. All are based on IEC950. And each one costs at least $2,000 US. Not only that, they keep changing, so we have to update the report on occasion - another expense. Big companies can afford this, but it is difficult for small ones with just a few employees. I too wish we could come up with a universal EMC/product safety certification. Darrell -- From: owner-emc-p...@majordomo.ieee.org To: 'emc-pstc' Cc: Dan Mitchell Subject: Are all these agencies really necessary? List-Post: emc-pstc@listserv.ieee.org Date: Wednesday, September 09, 1998 5:26PM The company I work for routinely requests that I get certifications through the following safety agencies: UL, VDE, SEMKO, DEMKO, NEMKO, FIMKO, EZU, QAS, GOST and ad nausium. My question is this; Are all these agencies necessary? If you get a base safety certification from say, UL, coupled with a CB Report/Cert and a third party EMC/EMI report to FCC ClassB, and EN50022, why is it necessary to get the safety agency for every country you want to sell in? Why can't this industry come up with an all encompassing mark, lets call it the OM (for Overall Mark) that is granted to your product after you get the following: 1. Base safety cert (from your agency of choice) 2. CB Report/Cert 3. FCC/Cispr22 cert THe mark would allow you to sell your product in any country in the world. It makes alot more sense than the way it is done now. I can spend up to 3 months waiting for a certification to come back from China. The cost is outragous also. If we spend $30,000 on the certification process, we count ourself lucky. I believe that alot of these new agencies that have been appearing on the scene over the last couple of years are in it strictly to make a buck. All they have to do is block your product from their market unless you pay their extortion money. I know that this is opening up a can of worms, but I would like to know if there are other disgruntled safety persons out there that feel the same way. This view is strictly my own. Daniel W. Mitchell Product Safety EOS Corp. - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.com with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, ri...@sdd.hp.com, or roger.volgst...@compaq.co (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.com with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, ri...@sdd.hp.com, or roger.volgst...@compaq.co (the list administrators).
RE: HELP
Brian, I've had good luck with Pacific Transformer Corp. in Anaheim, CA. Their phone number is 714-779-0450, fax 714-779-0718. Darrell -- From: owner-emc-p...@majordomo.ieee.org To: emc-p...@ieee.org Cc: Brian Harlowe Subject: HELP List-Post: emc-pstc@listserv.ieee.org Date: Wednesday, August 12, 1998 7:01AM I have an urgent problem. I need an open wound transformer with a primary tapped at 190-200-220-240 volts and a secondary at 240 volts. Rating is 3.5kVA and 50-60-Hz. Here comes the crunch it must be either UL or CSA listed to comply with current US regulations. Any Help will be gratefully accepted Brian Harlowe - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.com with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, ri...@sdd.hp.com, or roger.volgst...@compaq.co (the list administrators).
RE: Ce versus FCC
Your comment below is absolutely true. Manufacturers spend far too much time and money obtaining certifications for so many countries that have just minor differences in their standards. One standard for EMC/product safety is too simple I guess. Darrell -- From: owner-emc-p...@majordomo.ieee.org To: emc-p...@ieee.org Cc: rbus...@es.com Subject: Ce versus FCC List-Post: emc-pstc@listserv.ieee.org Date: Monday, July 06, 1998 1:10PM A test house explained to me that the FCC allows either CISPR or FCC limits/procedures providing that one can determine worst case. Consequently, you have to test both ways (120 V 60Hz or 230V 50Hz) to determine which way you should have tested. So, where are the time/money savings? As a personal note, it seems to me that there will always be slight differences whether it be, test sites, cables, input power, placement, whatever. The objective should be to reduce levels to reasonable, repeatable limits. Defining an acceptable standard or test procedure should be adequate. We should not have to incur unnecessary testing just to address a few dB one way or the other. Rick
RE: OATS gndplane surface
We have had great results using hardware cloth, overlapped about 5cm or more and spot soldered every 20cm or so with a heavy duty soldering iron. Our oats site has shown no deterioration in the last 5 years of existence. Very inexpensive. I don't know if the same material is available in Australia, but the material we use solders very easily. Regards, Darrell Upson -- From: owner-emc-p...@majordomo.ieee.org To: emc-p...@majordomo.ieee.org Cc: Martin Garwood Subject: OATS gndplane surface List-Post: emc-pstc@listserv.ieee.org Date: Tuesday, August 12, 1997 12:00AM Hi Gang, We are currently building another OATS and are looking into the most cost time effective way of achieving a uniform conductive groundplane without using mesh. Does anyone have experience with using galvanised metal sheet, and if so, the best method to join the sheets together (silver solder, braze etc), bearing in mind temperatures 45deg C in summer. Alternatively has anyone had success with conductive coating or paint over concrete ? Any thoughts would be appreciated. Best Regards. -- Martin Garwood, Manager, Austest Laboratories 4/87 Reserve Road Artarmon NSW 2064 AUSTRALIA ph: 61-2-94374500 fax: 61-2-94374600 http://www.austest.com.au
Re: Surge Suppressors
All of the power supplies that we use have surge suppressors built in. I'm sure that many manufacturers are shipping their products to the Nordic countries with similar power supplies. Darrell -- From: owner-emc-p...@majordomo.ieee.org To: ray_russ...@leco.com Cc: Rich Nute; emc-p...@ieee.org Subject: Re: Surge Suppressors List-Post: emc-pstc@listserv.ieee.org Date: Tuesday, May 13, 1997 12:58PM Hi Ray: In Norway, there is no guarantee that any particular outlet will include a ground. At NEMKO's main meeting room, the outlets do not have a ground! Consequently, in Norway, the condition of no ground is a NORMAL condition, not a fault condition. (Likewise, one-third of USA homes have no ground, and all Japanese homes have no ground!) So, Norway prohibits surge suppressors from being connected to 'earthed' parts of equipment. Now that we've put that issue to bed, let's look at another issue: Does a shock hazard exist because a surge suppressor is connected to grounded parts of equipment when the equipment is not connected to ground? Let's first define the surge. Can we assume the standard 1.5 x 50 impulse? If so, we are looking at a surge that decays to 63% of its peak value in 50 microseconds. It decays to nearly zero in 250 microseconds. We can further define the surge amplitude as not exceeding 1.5 kV. This is the dielectric withstand value of the primary-to- ground insulation. Let's assume the surge is less than 1.5 kV peak for less than 250 microseconds. Is this hazardous? Can the human body feel this pulse? Probably. Can the human body be frozen to the product by this pulse? No. Freezing requires continuous current through the body. Can the heart be caused to fibrillate by this pulse? No. Fibrillation requires the current to extend for the full duration of the T wave, i.e., more than 200 milliseconds. Can the human body be burned by this pulse. Yes. A current of 70 mA peak or more can cause a burn at 1 cm square contacts with the skin. It is likely that the body impedance will be less than 1500/0.070 = 21,428 ohms during this pulse. Note that protection against electric shock by the GFCI (aka ELCB, RCCB, RCD) provides protection by limiting the duration of the current through the body, not by limiting either the voltage or the current. When a GFCI operates, the subject gets the full voltage and whatever current, but only for a short period of time. In this way, it prevents fibrillation and freezing to the circuit. So, I submit that the impulse, while it can be felt and may create a burn, is not a shock hazard. Now that we've looked at electric shock, let's look at whether the impulse can appear on the grounded parts of the equipment when the equipment is not grounded. Ignoring the surge suppressors, and considering for a moment the EMC filter capacitors, we have the following circuit: L1 ...-+-+ | | | | ---+--- | CY1| ---+---- | | | Rload +---+ | | | | | | ---+---| - CY2 | | ---+---| | | | | | | | | | | L2 or N ...-+---)-+ | PE (non-existent) ...+ | | chassis - --- - If a surge appears between L1 and N, it will be divided in half by the action of CY1 and CY2. So, only one-half of the surge voltage will appear on the chassis. If a surge appears common-mode between L1/N and PE, then the full voltage will appear on the chassis because there is no current path (because the ground is open). We can replace CY1 and CY2 with surge suppressors. If a surge appears between L1 and N, the surge suppressors will not be turned on unless the suppressor voltage ratings are less than one-half the applied voltage. In this case, the circuit response to the surge remains the same as with the capacitors. If the suppressors are not turned on, then the circuit still behaves the same as with capacitors because of the capacitance of the suppressors. If a surge appears common mode, the surge suppressors will not be turned on because there
Re: Koreans EMC Approvals
Ed, Had to send this again as it didn't go through the first time. -- From: Upson,Darrell To: 'emc-pstc' Subject: Re: Koreans EMC Approvals List-Post: emc-pstc@listserv.ieee.org Date: Wednesday, April 09, 1997 5:52AM Ed, Thanks Ed for saying what was so obvious but you were the only one to speak up. What we all need is a world-wide standard. Everyone would benefit, instead we have to provide certification for Europe, North America, Australia, etc. There are over 300 countries that could be doing this. It must be the test labs that rejoice, while manufacturers waste time and money. Darrell -- -- Thank you, Ryan, for a very clear explanation of one of the most blatant trade barrier schemes I have ever seen. I suppose your ministry of trade wouldn't mind if every one of Korea's trading partners established similar reciprocal policies. -- Name: Ed Price E-mail: ed.pr...@cubic.com List-Post: emc-pstc@listserv.ieee.org Date: 4/8/97 Time: 12:52:50 PM --
Spread spectrum clock oscillator
Does anyone know of a source for a spread spectrum clock oscillator. We have a sample of a 20MHz spread spectrum oscillator that we find reduces radiated emissions readings from our products by several dB. The company name was IMI in Milpitas, California, but no longer exists. Any leads to a similar product would be greatly appreciated. Thanks, Darrell Upson Xerox ColorgrafX Systems, Inc.
