Hello Doug, The method as mentioned in CISPR 14 is not intended as an alternate method for an open area site measurement. The reason for this is that equipment, which is within the scope of the CISPR 14, is more likely to cause disturbances by means of radiated power from cabling than by means of radiated emission from the cabinet.
There once was a method defined in CISPR 22/EN 55022 which utilized a current clamp for measurements on cables. However, a note to this method also indicated that possible cabinet radiation should be taken into account when interpreting the results. From personal experience I can tell you that complying with the limits of the current clamp measurement doesn't imply compliance with a measurement on an open area site. Results regarding this type of measurement would only indicate whether your cables are properly connected and/or filtered. In my opinion you should only use a current clamp when your type of equipment is within the scope of a standard which describes this method as the proper method of measurement (CISPR 14 and CISPR 15). Measurements on cables of other equipment would only indicate if you are on the right track and would not give real confidence regarding compliance on an open area test site. Also bundling cables through a current clamp is not advisable. For instance, capacitive coupling between the cables in the bundle would affect the result of the measurement and may not give you correct results. The best way to do this measurement is testing one cable at a time. The current clamp which is mostly used is the one from Luthi or Rohde & Schwarz (which seems to be also Luthi). I believe the type is EM 101 for the Luthi brand. This will fit cables up to approx. 10 mm. Best regards, Pieter Robben Manager, location Niekerk of NMi Certin B.V. NB/CB for EMC, TTE, Radio and Low Voltage Dir. Tel: +31-594-505005 / 1-860-873-1454 (USA) Email: [email protected] / [email protected] (USA) At 99/02/11 12:28 PM, you wrote: >Hello Group, > >Some time ago (1996) in an email thread on absorbing clamps, Michael A. >Royer stated that CISPR 14 defines a method for using current clamps instead >of open area test sites. There was another thread for an on-site radiated >emissions test when in noisy environments that mentioned using clamp-on >probes. > >Additionally I recall and article in one of the trade magazines (Compliance >Engineering, ITEM, etc.) that described a method where a person could bundle >all of the service connections for a product into an RF current clamp-on >probe. The article also had information on converting the data on a >spectrum analyzer into equivalent open area test site numbers. > >I would like to perform a test like this but have been unable to find a >clamp-on probe that has at least a 100mm inner diameter and a frequency >range of 30 MHz to 1000 MHz, possibly this is limited by physics. > >Is there anyone out there who is able to point me to articles or websites >on: > >1) RF current probe manufacturers. >2) The article and/or mathematical algorithm on measuring radiated >emissions with current probe. >3) Application information. > >Thank you for any help you can provide. > >================================== >Doug Powell, Compliance Engineer >Advanced Energy Industries, Inc. >Fort Collins, Colorado USA > >[email protected] >www.advanced-energy.com >================================== >
