Some Questions about PC & PC ISA card safety standards in both the USA and Europe.
Background I am responsible for a PC ISA card that is used to interface a PC to a twisted pair industrial communications system. The card is powered from the PC 12 Volts - no fuse. The twisted pair signal is transformer isolated and the signal is 5 Vpp. At present the transformer can take a 1500 VRM/1 minute hipot, however it does not meet IEC 950 construction requirements. We are presently modifying several designs to meet CE mark LVD requirements while we believe we understand and have dealt with the EMC requirements. This has resulted in the following Questions: 1) Is it a given that all PCs meet UL1950 or IEC 950 directly or indirectly? I understand that family standard IEC1131 refers to IEC 950 for safety. 2) Would my card need to meet UL1950 for the USA market? If no - is there any perceived market value by meeting 1950 for this card? 3) Would my card need to meet EN60950 (IEC 950) to satisfy the CE mark LVD? I realize that the power and signal level are well below the required levels to be considered by the LVD however if considered as part of the PC then it is not so clear. 4) Is there a market expectation to see EN60950 on a PC card in Europe? By now I imagine you all get the intent of my questions. If there is anything else you feel is important to consider "safety wise" on the topic of PC cards, I would very much appreciate it Regards Chris Wells Sr Des. Eng. Cutler-Hammer [email protected]
