hello EMC group,
last week we performed EMI measurements on an industrial printer. The printer is a very large device, about the size of a volleyball field. It has two mains inputs (400V, 3 phases + neutral) rated at 125Amps and 200Amps, respectively. There are a large number of industrial cabinets with high-speed digital electronics, PLC circuits, inverters, fuzes, sensors, pneumatic circuits, ... and motors to (1) pickup paper, (2) transport/feed it into the imaging section, (3) deposit ink using a one-axis movement robot with over 50 printing heads, (4) partial curing using UV-light (5) pickup and move it to the final drier section using - once again, UV - and (6) move it to an output/stacking unit. If we consult CISPR11:2003 we have to classify this equipment into a class and group. The class is the easy part: class A. Wrt the group definition it seems that we are group 1, that is, we do not generate (intentionally) electromagnetic radiation for the treatment of materials. Actually, we use electromagnetic energy to generate heat, UV light and motion (and power digital circuits). In standby the printer is on or slightly above the class A, group 1 conductive limit(for both QP and average emissions). In printing mode the conducted emssions rise by about 20dB in the frequency range of 150kHz to 2MHz. We do not understand this behavior, but this is currently not the concern. One last piece of information: the conducted emissions were measured using a voltage probe as described in CISPR11. Here are my questions: -1- is there a voltage probe limit for class A group 1 devices? It is not in the standard, that is for sure! So can I add 30dB to both QP and average limits? (To derive a class A group 1a limit, as a manner of speaking?) -2- Why not classify the device as a group 2a device? It seems this is also a possibility as there are no other limits in CISPR11 for equipment rated over 100Amps. If you look at annex A of CISPR11:2003 then I have the impression that the scope of group 2 is wider and could include equipment that does not require intentional generated electromagnetic radiation for its operation (e.g. thyristor-controlled equipment --> transistor inverters which we use) It seems not unfair to use similar limits (that is, use group 2a) for equally current-rated (over 100 Amps) group 1 equipment measured with the CISPR11 voltage probe. Any suggestions, an opinion?? Thank you, Jan Vercammen - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
