ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 2 [3]   Go Down

Author Topic: Popping a 5000 amp fuse  (Read 1452 times)

Russell Ault

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1393
  • Edmonton, AB
Re: Popping a 5000 amp fuse
« Reply #20 on: June 13, 2021, 12:20:15 AM »

The original ubiquitous "non-battery" EV, (commonly known as a diesel-electric locomotive), average around 3.2MW from their onboard power plant -I bet there's some large current fuses in those. 
Not to mention some interesting computer controlled traction control via very large solid-state motor drives.

-I'm always been fascinated by anything that starts with logic-level voltages in microscopic silicon ending up in control of stunning amounts of raw current! 

Do they have multi-megawatt breakers that wouldn't need contacts rebuilt after opening (especially with DC)?  Possibly would be too large and heavy for anything other than stationary power-plant or substation usage?

Judging from the manual for the GE Dash 8 Series, it appears that "motor cut-out switches" act as over-current (as well as flash-over) protection devices, and there's no indication that there are any precautions for their use (beyond, potentially, a horsepower de-rating when operating the locomotvie with only the remaining motors). For what it's worth, a lot of DC diesel-electric locomotives have a nominal maximum operating current of ~1000 A or less, and that's across all traction motors, so any individual over-current device should "only" need to be able to handle no more than about 250 A DC (which is still no mean feat, but a far cry from 5 kVa).

And it looks like these will easily do a MW, and they aren't even that big. (Strictly speaking this isn't a "breaker", but it could easily be used as part of an over-current protection system.)

-Russ
Logged

Steve-White

  • Hero Member
  • *****
  • Online Online
  • Posts: 698
  • Fort Worth
Re: Popping a 5000 amp fuse
« Reply #21 on: June 13, 2021, 12:52:50 AM »

I built a few Tesla coils back in the high school days.  Two of them worked out well, one would push 12" sparks into the air.

One of the guys in my Electronics class built a huge Tesla coil with a secondary about 8' tall.  Never got much more than 12-18" arcs from it - something was off on the tuning or coupling - probably had too much air space between the primary and secondary coils.  It either was losing it in the coupling or the capacitance was off on the primary and it didn't hit resonance.

https://soulspiritguidance.com/wp-content/uploads/2017/12/CPxgoNnXAAEmvRf.jpg

What he was up to at Wardenclyffe has always fascinated me.

 
« Last Edit: June 13, 2021, 12:55:56 AM by Steve-White »
Logged

Stephen Swaffer

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2478
Re: Popping a 5000 amp fuse
« Reply #22 on: June 14, 2021, 01:13:06 PM »

My facility had a fused main disconnect-with 3000 amp fuses.  We replaced it with a breaker a couple of years ago.

Often, fuses are a better choice to reduce arc flash, because they can interrupt current faster than breakers.  Unfortunately, when you get into fuses that large, the available fault current may not be high enough the quickly blow the fuse.  IIRC the fault current I calculated was somewhere around 12,000-15,000 amps-which put the clearing time for the fuses in questions around 2-3 seconds.  I'm thinking it would seem like a lot longer than 2-3 seconds in the event of a fault like that!
Logged
Steve Swaffer

Daniel Levi

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 530
Re: Popping a 5000 amp fuse
« Reply #23 on: June 14, 2021, 03:38:03 PM »

We now need a Photon and Bigclive collaboration, that would be fun.
Logged

Russell Ault

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1393
  • Edmonton, AB
Re: Popping a 5000 amp fuse
« Reply #24 on: June 14, 2021, 03:48:55 PM »

{...} Often, fuses are a better choice to reduce arc flash, because they can interrupt current faster than breakers. {...}

This is fascinating to me; does this just apply to thermally-triggered breakers, or is this true for any reset-able over-current devices?

-Russ
Logged

Brian Jojade

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2098
    • HappyMac Digital Electronics
Re: Popping a 5000 amp fuse
« Reply #25 on: June 15, 2021, 01:09:22 AM »

My facility had a fused main disconnect-with 3000 amp fuses.  We replaced it with a breaker a couple of years ago.

Often, fuses are a better choice to reduce arc flash, because they can interrupt current faster than breakers.  Unfortunately, when you get into fuses that large, the available fault current may not be high enough the quickly blow the fuse.  IIRC the fault current I calculated was somewhere around 12,000-15,000 amps-which put the clearing time for the fuses in questions around 2-3 seconds.  I'm thinking it would seem like a lot longer than 2-3 seconds in the event of a fault like that!

The job of a fuse is to protect things.  In the case of a massive fault, 2-3 seconds would probably be fast enough that it would fail before any connecting lines heated enough to be damaged.  Just like the fuse, a piece of wire can handle a LOT more current than it's rated for for short durations.  It's a factor of time vs heat generated and dissipated.
Logged
Brian Jojade

Stephen Swaffer

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2478
Re: Popping a 5000 amp fuse
« Reply #26 on: June 15, 2021, 12:24:21 PM »

This is fascinating to me; does this just apply to thermally-triggered breakers, or is this true for any reset-able over-current devices?

-Russ

I am sure it would apply for any resettable device-there is a finite inertia of the mechanisms that must be overcome and the larger the current the heavier those mechanisms are.  The disconnect in the fused switchgear was a massive switch.  I suppose I should dig back into my physics books and look at the formulas for momentum and acceleration-but you are looking at very small fractions of a second clearing time.

Brian-you are correct.  I was picturing in my minds eye an arc flash event lasting 2 or 3 seconds.
Logged
Steve Swaffer

Jared Bartimus

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 64
  • Normal, IL
Re: Popping a 5000 amp fuse
« Reply #27 on: July 02, 2021, 06:52:15 PM »

No Health and Safety issues with this :o ;D

He actually has some pretty decent Health and Safety practices.  Including using a pneumatic switch to activate his high voltage supplies.  He has a video where he went through his other "policies" when playing with electricity.
Logged

ProSoundWeb Community

Re: Popping a 5000 amp fuse
« Reply #27 on: July 02, 2021, 06:52:15 PM »


Pages: 1 2 [3]   Go Up
 



Site Hosted By Ashdown Technologies, Inc.

Page created in 0.07 seconds with 25 queries.