Hi Brian. << Just to add a little more fuel to the flames! We supplied an Instrument to a well known semiconductor Manufacturer in Oregon which was powered from two 220 volt phases. I marked the rating plate as 220 volt one phase as has been suggested. However the local inspector made us change it to 220 volt two phase. So what is the correct definition. >>
I was always encouraged to describe a supply by how many phases were not earthed, and a device by how many phases it used. In that context there is no such thing as a two phase device, at least not in the UK, as a two phase device would have three wires and the third phase is already there as the algebraic sum of the two phases. In the UK the distribution system is Earthed Neutral 3 phase equal star. In the USA and many other places there are all sorts of systems, e.g. open delta - earthed centre tap one phase, close delta earthed on phase, two phase earthed centre tap... the list is long.. In the UK, we use 1 phase and neutral, or three phases with or without neutral. Industrial systems use 2 phases, usually for control transformers which are single phase devices running at 415V, as there is no neutral. In the UK neutral and Earth are tied together at the distribution room, but NO current is permitted in the local Protective Earth conductor or the 30mA RCD's trip. I think your local inspector was probably OK in asking for the label to say Two Phase, as it was a Single phase device connected to Two phases. Sound reasonable? Chris Dupres Surrey, UK. ------------------------------------------- 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
