Hello Don: A response to each question is below. ---------- From: donald.han...@bangate1.tek.com[SMTP:donald.han...@bangate1.tek.com] Sent: Friday, January 31, 1997 10:34 AM To: emc-p...@ieee.org Subject: Modem isolation
Question: Hello, I'm interested in the isolation requirement for telcom connections and in particular modem isolations. Several year ago in some EU countries to get a modem for your computer you went through the Telcom Authorities and they would make sure your computer had acceptable isolation built into it before installing the modem. If you computer didn't have the proper isolation you didn't get the modem. Question: With the implementation of the Telcom Directive what is the status in the EU? Response: You will still need to meet the requirements of the LVD (Low Voltage Directive). The applicable standards here are EN 41003: "Particular Safety Requirements for Equipment to be Connected to Telecommunication Networks", and EN60950: "Safety of Information Technology Equipment, Including Electrical Business Equipment". Question Do some countries still require isolation to be built into the computer? Response: Yes. All countries in the EU will require isolation that meets the requirements of the above standards. Question: Do most modem manufacturer' build the isolation into the card? Response: I do not believe a modem manufacturer could get by without at least a SUPPLEMENTARY INSULATION barrier between the card and the telephone network, as defined in the above standards. The purpose of this barrier is to protect the Telecommunications Network, more specifically the service personnel from the mains voltage. A REINFORCED or DOUBLE INSULATION barrier is required between the mains voltage and the network, and a SUPPLEMENTARY INSULATION barrier is required between earth and the network. The DOUBLE INSULATION barrier can be provided by a combination of BASIC and SUPPLEMENTARY INSULATION. To my knowledge, any computer approved for sale in the EU these days would need a REINFORCED INSULATION barrier to carry the CE mark between the mains and accessible parts (the innards of the computer where someone might plug in a modem card). So I do not think you would have a problem getting a stand alone modem card approved for sale as it is assumed that the user has a CE marked computer. However, you would still need the SUPPLEMENTARY INSULATION to protect the network from earth to get your approval. This, of course, means a transformer providing sufficient isolation. Thanks in advance, Donald A. Hanson Mgr. Product Safety MBD Tektronix, Inc. I hope that was helpful. I could go on, but that should give you a start. Let me know if you have any more questions! All known disclaimers apply. Mel Pedersen Midcom, Inc. Homologations Engineer Phone: (605) 882-8535 e-mail: mpeder...@midcom.anza.com Fax: (605) 886-6752
