The issue is getting the required field strength: 1A (roughly) through a 1m coil will produce about 1A/m field in the center of the coil. Anything bigger than .3m in any dimension, won't be stressed adequately.
For bigger stuff, you need a bigger coil, but the problem is you then need more current to get the same field strength: a 2m coil requires 2A, etc... Using multiple turns allows you to keep the current down. For a 1 meter coil, you can get 1A/m from a current of roughly 0.5A. The numbers don't exactly work because of losses in the coil: The coils we buy have a coil factor of about .85, which means they are 85% efficient and you need about 15% more current to get the correct fields. Other coils will have other factors, depending on their design. You can call Fischer Constant Communications -- I believe they've made some very big coils for some customers: FCC 2905 W. Lomita Blvd. Torrance, CA 90505 Tel: 310 891 0635 Fax: 310 891 0644 Hope this helps,,,,, Mike Hopkins KeyTek -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: Tuesday, January 16, 2001 11:42 AM To: [email protected] Subject: EN 61000-4-8 We will have to apply the magnetic field immunity test to some of our Generic and ITE products in order to comply with the new revisions of the standards. One of the tests is not clear to us. Consider a product whose width and depth are such that it fits correctly inside the standard 1 m loop, but also assume that the equipment height exceeds 0.5 m. On one hand, the standard tends to indicate that a two or more loops are required to ensure that the entire height of the equipment is immersed during a single test. But on the other hand, there is mention of moving a single loop over the height of the equipment. Do I understand correctly, that tall (> 0.5 m) equipment may be tested using a single 1 m loop that is moved along the height of the equipment? Richard Woods ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
