It is currently Sat Oct 31, 2020 5:30 am

Author Message

 Post subject: Fuses in parallelPosted: Sun Jan 22, 2012 5:21 pm

Joined: Sun Jul 22, 2007 5:00 pm
Posts: 33
Location: Stratham, SW Australia
When an arcing fault occurs downstream from two 100A fuses in parallel, can the fuses modelled by a single 100A fuse by shifting the current axis to the right by a factor of two to represent the time-current curve for the two parallel 100A fuses ?
The above assumes that the current divides equally between the two 100A parallel fuses.

Top

 Post subject: Posted: Tue Jan 24, 2012 5:12 am
 Plasma Level

Joined: Mon Sep 17, 2007 5:00 pm
Posts: 1519
Location: Scottsdale, Arizona
mnewman wrote:
When an arcing fault occurs downstream from two 100A fuses in parallel, can the fuses modelled by a single 100A fuse by shifting the current axis to the right by a factor of two to represent the time-current curve for the two parallel 100A fuses ?
The above assumes that the current divides equally between the two 100A parallel fuses.

What voltage? Medium Voltage fuses have a parallel mounting for larger ratings. i.e. 540E which is made up of 2 - 300E fuses in parallel. 540E = (2 x 300E) x 90% The curve is specific for a 540. I did not overlay a shifted 300E TCC with a 540E but it looks like the shapes are similar.

In the U.S. we don't parallel LV fuses (except perhaps cable limiters on networks)

_________________
Jim Phillips, P.E.
Brainfiller.com

Top

 Post subject: Posted: Sat Jan 28, 2012 5:51 am
 Plasma Level

Joined: Tue Oct 26, 2010 9:08 am
Posts: 2174
Location: North Carolina
There is a small problem with this. The average fuse rating doubles but the fuse accuracy goes down. Fuse curves show a range of values to accomodate a +/-% factor. If you parallel them, you might get a batch which are both on the extreme to either the positive (bad from an arc flash point of view) or negative side.

Top

 Display posts from previous: All posts1 day7 days2 weeks1 month3 months6 months1 year Sort by AuthorPost timeSubject AscendingDescending
 Page 1 of 1 [ 3 posts ]

 All times are UTC - 7 hours

 You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum

 Jump to:  Select a forum ------------------ Forum Library / Articles The Lounge    Question of the Week - What Do You Think?    Arcflashforum.com Feedback and Announcements    Off Topic Discussions    News in Electrical Safety Arc Flash and Electrical Safety    General Discussion    Electrical Safety Practices    Equipment to Reduce Arc Flash Dangers    Personal Protective Equipment (PPE) Arc Flash Studies    General Discussion    Arc Flash Labels    Software for Arc Flash Studies    System Modeling and Calculations    NEW! Electrode Configuration Library – 2018 IEEE 1584 Codes and Standards    CSA Z462 Workplace Electrical Safety    EAWR Electricity at Work Regulations, HSE - Europe    OSHA CFR Title 29    IEEE 1584 - Arc-Flash Hazard Calculations    NFPA 70 - National Electrical Code - NEC (R)    NESC - ANSI C2 - National Electrical Safety Code    NFPA 70E - Electrical Safety in the Workplace    2015 NFPA 70E Share It Here    Arc Flash Photos    Your Stories    What's Wrong Here? by Joe Tedesco
© 2019 Arcflash Forum / Brainfiller, Inc. | P.O. Box 12024 | Scottsdale, AZ 85267 USA | 800-874-8883