EN60079-15 is based on limiting temperatures and limiting arcs to avoid ignition of an explosive atmosphere. The concern with cells in parallel is that an unequal division of current will cause heating beyond that anticipated and that heating could cause autoignition of a flammable atmosphere. The General Requirements for explosive atmospheres, EN 60079-0, permits only cells in series. But, as EN 60079-15 addresses only Category 3 equipment (per 94/9/EC) a slightly higher risk of ignition can be tolerated, and thus the two cells in parallel are permitted. Bill Lawrence FM Approvals
_____ From: [email protected] [mailto:[email protected]] On Behalf Of MacArthur, Don Sent: Monday, August 13, 2007 3:02 PM To: [email protected] Subject: ATEX Requirement for Cell Connection EN 60079-15: 2005 which is titled Electrical apparatus for explosive gas atmospheres – Part 15: Construction, test and marking of type of protection “n” electrical apparatus, and other hazardous locations standards have cell connection requirements which are as follows: “Cells shall be connected in series except for the specific case where two cells are connected in parallel with no further cells connected in series.” My questions to the group are: 1. Why is the above statement a requirement? Worded another way… 2. What is the safety issue when cells are connected in series with some in parallel when the cells are used in an explosive gas atmosphere? I’ve asked around various safety agencies and have not received a response let alone any response that makes sense. Kind Regards, Don Don MacArthur Compliance Engineer General Dynamics - Itronix Corporation 12825 E. Mirabeau Parkway Spokane Valley, WA 99216 ph: 509-742-1342 fax: 509-742-1672 email address: <mailto:[email protected]> [email protected] “This email message is for the sole use of the intended recipients and may contain GDC4S confidential or privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not an intended recipient, please contact the sender by reply email and destroy all copies of the original message.” - ---------------------------------------------------------------- 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 ______________________________________________________________________ - ---------------------------------------------------------------- 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
