Hi Peter: > For back-up power supply connections to a device which has means for > connection to a floating dc input of 44-57 Vdc / 15 A max (to serve as > back-up source for the internal power over LAN source), what is the proper > way of marking with symbols to IEC60417 Does the power-consuming device REQUIRE the source to be floating? If yes, then I don't believe there is any suitable symbol in IEC 60417. I believe you will have to design a suitable marking indicating that the source must have NO connection to earth. Furthermore, I would guess that you would need to specify a minimum source-to-earth impedance. I believe this source requirement to be highly unusual. I suspect what you mean is that the supply circuit in the device is floating (which is the typical case). If this is the situation, then there is no need to so identify it as this is a design that will tolerate any source configuration (i.e., negative pole is grounded, or postive pole is grounded, or neither pole is grounded). > 2) To specify that it is a back-up source of supply (vs. primary source of > supply). Again, I don't believe there is any IEC symbol that represents the terminals as being for connection to a back-up source of supply. Your situation is opposite that of the conventional situation. The conventional situation is where the external source of supply is the normal supply, and the internally-derived source of supply is the back- up. In your case, the internally-derived (LAN) is the normal source of supply, and the external source of supply is the back-up. For your product, the back-up terminals should be suitably marked with rating markings. However, connection of the terminals to a source of supply is optional as the connection is for a back-up source of supply. Identification of the terminals and their connection for back-up purposes can be by text on the product itself, or in the installation instructions. Best regards, Rich ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
