All, I have the following specification:
ANSI/NEMA WC27500 (shielded or unshielded, jacketed cable using AS22759/43 wires). AS22759/43 states the following requirement: 200 deg. C, 600 V (rms) @ sea level, dielectric test: 2,500 V (rms) at 60 Hz, Impulse dielectric test: 8.0 kV (negative polarity peak w/ 90% of peak at a rise time of 75 u sec., damped to 80% within 20 to 100 u sec., damped to less than 1% before the next pulse starts - repeats between 200 to 250 times/sec.) My questions are: a) Why is the impulse dielectric test at 8 kV specified to be a negative polarity? Is this entirely arbitrary? Can one assume that the negative polarity application covers the eventuality of a positive polarity transient? b) What if a transient were to occur at a much faster risetime? Does the wire insulation respond only to applied potential, or potential rate-of-change? c) What if the transient occurs at a much slower rate than 200 pps? Does the insulation breakdown depend on number of hits per unit time? Can it take a higher potential that occurs at a much lower rate of application? Thank you in advance, Ken Javor Phone: (256) 650-5261 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]>
