Hi Eric, Thanks for reminding us of checking Safety issues of Ethernet port.
I have a few questions about the Ethernet port: 1. A phone line port has to comply with related regulations in Telecom world. In my recollection, PC industry just added an Immunity requirement to the phone line port. (It is included in EN55024?) But Ethernet can be converted to phone line through an adapter. Is there a similar immunity requirement for the Ethernet port in test equipment? If not, should it be added to EN61326? 2. You are right when saying, shielded network cable will at least direct a significant portion the surge or transient energy to the ground system. But I dont think we are allowed to waive EN61000-4-6 for ports with shielded cable. (We can waive I/O ports with less than 3 meter cable.) The purpose of test method defined in EN61000-4-6 is to induce common-mode RF current flowing through the EUT. The EUT does not have direct grounding points in the test. As a matter of fact, EN61000-4-6 specifies how to test shielded cable. Please refer to Fig. 8b Definition of a common-mode point with screened cables. Regards, Barry Ma ---------------- On Thu, 13 July 2000, [email protected] wrote: Barry et al, Certainly, we're adding more Ethernet based data acquisition and control products all the time. The applicable EMC standard is still the relatively new product family standard EN 61326-1, with it's counterpart for safety EN 61010-1. The Ethernet port has overvoltage features that should be checked (creapage, clearance, dielectric strength) that I suspect many folks neglect to do. We call for the use of shielded CAT 5 cable for our latest products being tested to EN 61326-1. A desktop computer is not too painful to replace after a damaging surge event enters the enclosure on unshielded cable, an instrument like yours/ours at many times the cost (plus the loss of it's use) is another matter. The hope is that shielded network cable will at least direct a significant portion the surge or transient energy to the ground system; or maybe to a less costly device elsewhere (like the local network hub). And, a hard benefit to ignore is that in EN 61326-1 the 61000-4-6 RF test is waived for I/O ports if you specify to the customer the use of shielded cable. So shielded cable also saves us a lot of test time. (I wonder if this tidbit will provoke another thread denouncing EN 61326-1? Poor EN 55024 guys.) By the way, I think the brain chip has a standard now, they call it BlueSkull :) Best Regards, Eric Lifsey National Instruments Thanks. Best Regards, Barry Ma <[email protected]> ANRITSU www.anritsu.com Morgan Hill, CA 95037 Tel. 408-778-2000 x 4465 _______________________________________________________________________ $1 million in prizes! 20 daily instant winners. AltaVista Rewards: Click here to win! http://shopping.altavista.com/e.sdc?e=3 _______________________________________________________________________ ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
