Magnetic field near a condcutor 300 A DC - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 31st October 2007, 11:47 AM   #1
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
Default Magnetic field near a condcutor 300 A DC

How many Tesla is healthy for my Traco TME DC-DC converters? My concern is if the DC-DC converter may get saturated transformer cores.

My application is two 300 A, DC 10 x 20 mm copper bars 60 mm apart (50 mm space). Between the copper bars I’m going to place a H-bridge driver including three 12 V DC-Dc converters.

A forumla says 0.3 Tesla 1 cm from the conductor. This seems much. Anybody who have a theorectical insight in this?

The current flows is different directions.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Super Regulator SSR03 Group buy
  Reply With Quote
Old 31st October 2007, 12:00 PM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
if the current flows in opposite directions then the far field effect is near zero.
Close up or between the conductors will have a much bigger effect.

Keep the TV and compass at bay.
__________________
regards Andrew T.
  Reply With Quote
Old 31st October 2007, 12:06 PM   #3
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
Andrew, my question is what happens bewteen the copper bars.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Super Regulator SSR03 Group buy
  Reply With Quote
Old 31st October 2007, 02:29 PM   #4
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Default Re: Magnetic field near a condcutor 300 A DC

Quote:
Originally posted by peranders
How many Tesla is healthy for my Traco TME DC-DC converters? My concern is if the DC-DC converter may get saturated transformer cores.
Hopefully, traco will specify the sensitivity of their supply design to external DC magnetic fields. There will be minimum as well as maximum orientation sensitivity, depending on the design of their ferrites.

There will also be a temperature component to that sensitivity as well, higher temps of course being worse for magnetic sensitivity.

As posed, that specific question is not answerable by anybody other than the manufacturer.




Quote:
Originally posted by peranders

My application is two 300 A, DC 10 x 20 mm copper bars 60 mm apart (50 mm space). Between the copper bars I’m going to place a H-bridge driver including three 12 V DC-Dc converters.

A forumla says 0.3 Tesla 1 cm from the conductor. This seems much. Anybody who have a theorectical insight in this?

The current flows is different directions.

Go here:

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

Under Biot-Savart, there is a calculator for a single loop magnetic field.

Just looked at what the link gives..

Click on ele and magnetism...then biot-savart, scroll down to the pic of the single loop, click on it.


Cheers, John
  Reply With Quote
Old 31st October 2007, 03:15 PM   #5
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
I have just tested with 2000 A and the inpact was minor, I'd say. Less than 100 mV on a 5V to 5V converter. It may be nothing to worry about.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Super Regulator SSR03 Group buy
  Reply With Quote
Old 31st October 2007, 03:28 PM   #6
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
Anyway, at a distance of 1cm you only get 0.006T (for one conductor, in the air).
There will also be a contribution of the other conductor, but it will be lower: 1/5th.
LV
  Reply With Quote
Old 31st October 2007, 04:48 PM   #7
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
Can you tell me the formula? I've got 0.3 T which seemed way out wrong.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Super Regulator SSR03 Group buy
  Reply With Quote
Old 31st October 2007, 05:14 PM   #8
diyAudio Member
 
PigletsDad's Avatar
 
Join Date: Jul 2007
Location: South Worcestershire
Default Magnetic field near straight filamnetary conductor

For a long straight, filamentary conductor

B = mu0 2i / 4 pi R

where mu0 = 4 pi x 10^-7, i is the current in amps and R is the radius in meters.

cancelling the 4pi gives

B = 2 x 10^-7 i /R

For R = 1cm and i = 300A, this is 6x10^-3 T

For an extended conductor, you should really integrate over the cross section, but usually just measuring the radius from the centre is close enough, which reduces B a bit more.

I would be amazed if 6mT had much effect on the ferrites.
  Reply With Quote
Old 31st October 2007, 05:27 PM   #9
diyAudio Member
 
jneutron's Avatar
 
Join Date: Jan 2004
Location: away
Default Re: Magnetic field near straight filamnetary conductor

Quote:
Originally posted by PigletsDad
For a long straight, filamentary conductor

B = mu0 2i / 4 pi R

where mu0 = 4 pi x 10^-7, i is the current in amps and R is the radius in meters.

cancelling the 4pi gives

B = 2 x 10^-7 i /R

For R = 1cm and i = 300A, this is 6x10^-3 T

For an extended conductor, you should really integrate over the cross section, but usually just measuring the radius from the centre is close enough, which reduces B a bit more.

I would be amazed if 6mT had much effect on the ferrites.
As you stated correctly, the formula is for a long straight conductor.

Outside of the actual conductor, assuming circular cross section, the field will be independent of the size of the conductor. If the conductor is not cylindrical, that will not be correct.

For the problem at hand, if the supply is between the two conductors, field will enhance, it will be necessary to double the strength calculation...a whopping 12 mT..

If the 300 amps forms a loop, it can be as much as pi times 6 mT. It was the loop case I linked to.

Sheesh, at those field strengths, shouldn't there be some kind of safety barrier???

Cheers, John

ps...it's great to see others using Max's stuff..
  Reply With Quote
Old 1st November 2007, 02:21 AM   #10
jcx is online now jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
I wouldn't dismiss a free air 12 mT - it represents enoungh H to saturate some ferrite materials, μ_r of 500 gives B of 0.6T

a Iron (low carbon steel) box would divert the flux, shielding the smps magnetics
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Carver Magnetic Field Power Amp -whazzit???? rcavictim Everything Else 159 30th July 2014 03:59 PM
tracking and magnetic field power supplies RogerG Power Supplies 2 26th May 2005 07:47 PM
Magnetic field insulator GiveMeBoost Everything Else 22 21st April 2005 06:12 AM
Can a magnetic field rotate axially? Circlotron Everything Else 10 14th November 2002 03:38 AM


New To Site? Need Help?

All times are GMT. The time now is 01:09 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2