B-H Curve Tracer - diyAudio
Go Back   Home > Forums > Design & Build > Equipment & Tools

Equipment & Tools From test equipment to hand 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 30th November 2008, 07:39 PM   #1
gpapag is offline gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Default B-H Curve Tracer

Hi all

I found a bit of free time to build a very simple circuit by which the B-H curve of a transformer can be traced on the screen of a dual channel oscilloscope.

The circuit is from an old book titled “Transformer and Inductor Design Handbook” by Colonel Wm.T.McLyman (JPL).

The B-H curve as traced on the scope is a mirror image (left to right) of the actual one, but this is not a big problem.

It can be used in observing the point (input voltage) of core saturation, also to compare different x-formers. (In all cases with secondary open-circuit).

The resistor values in the circuit are for primary voltage of 230V and for primary Idle current of around 50mA.
Oscilloscope should be set to 2v/div on both channels (probe X1).

Caution:

Lethal voltages present.

It is mandatory to have a safety isolation transformer to provide the voltage to the primary of the x-former under observation.


Regards
George
Attached Images
File Type: jpg dscn6128.jpg (79.5 KB, 564 views)
  Reply With Quote
Old 30th November 2008, 07:40 PM   #2
gpapag is offline gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Default Screenshot 1

B-H curve from a x-former fed with 207V (-10 % of nominal)
Attached Images
File Type: jpg dscn6122.jpg (28.3 KB, 462 views)
  Reply With Quote
Old 30th November 2008, 07:42 PM   #3
gpapag is offline gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Default Screenshot 2

B-H curve from a x-former fed with 230V (nominal)
Attached Images
File Type: jpg dscn6123.jpg (61.3 KB, 441 views)
  Reply With Quote
Old 30th November 2008, 07:43 PM   #4
gpapag is offline gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Default Screenshot 3

B-H curve from a x-former fed with 242V (+5 % of nominal)
Attached Images
File Type: jpg dscn6124.jpg (61.4 KB, 431 views)
  Reply With Quote
Old 30th November 2008, 07:44 PM   #5
gpapag is offline gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Default Screenshot 4

B-H curve from a x-former fed with 253V (+10 % of nominal)
Attached Images
File Type: jpg dscn6125.jpg (59.5 KB, 429 views)
  Reply With Quote
Old 1st December 2008, 05:25 PM   #6
diyAudio Member
 
Join Date: May 2005
Location: Avesnes/Helpe
Hi,

I'm a physics teacher and i use nearly the same topology in my lab:

amp clamp meter in primary of transformer: I1 that is a mirror of H

H=N1.I1/L (L average length of core,N1 primary turns)

RC integrator in secondary (R=1M , C=1uF time constant=1s)

B=(1/(N2.S)).V2 (V2=output of integrator, S Cross section Area)

Main frequency is 50Hz.

with this method, it's very easy to trace B=f(H) with actual values.
  Reply With Quote
Old 1st December 2008, 07:38 PM   #7
Ron E is offline Ron E  United States
diyAudio Member
 
Ron E's Avatar
 
Join Date: Jun 2002
Location: USA, MN
So does the load on the Xfrm affect the B-H curve in any way, other than a temperature dependence type effect?

I presume inductors could be hooked across the same output terminals?

V, H, G are vertical, horizontal and ground, right?

So the isolation xfrm would be on the input side?
__________________
Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan
Armaments, universal debt, and planned obsolescence--those are the three pillars of Western prosperity. —Aldous Huxley
  Reply With Quote
Old 2nd December 2008, 05:37 AM   #8
gpapag is offline gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Hi all

Alexclaire

Thank you for the valuable information.
I intend to build a more involving unit for to be able to view a “calibrated” curve.
The 50R has to be scaled in value and wattage for different primary currents (magnetization Current Im) and Vprim and the integrator components have to be scaled for different Vprim and different frequencies (so the unit can be used for audio x-formers as well).
When I will build it (or sketch it on paper) I will post here for comments.

Ron E

Rod Elliot here insists that “For any power transformer, the maximum flux density is obtained when the transformer is idle”
I think that he is correct.
When this circuit is built in a proper way, it will show it.

Yes. The H, G, V in the diagram correspond to the points where the Horizontal (H), Ground (G), Vertical (V) inputs of the Oscilloscope will be connected.

Yes. The secondary (output) of the isolation x-former will be connected to the primary (input) of the device under test (DUT)

Regards
George
  Reply With Quote
Old 16th January 2011, 07:59 PM   #9
gpapag is offline gpapag  Greece
diyAudio Member
 
gpapag's Avatar
 
Join Date: Nov 2002
Location: Athens-Greece
Hi all

Here is a link with a circuit for B-H curve plotting and very useful formulae

Plotting Magnetization Curves

Regards
George
__________________
["Second Law is a bitch." - SY] ["The Road To Heaven:Specify the performance & accept the design. The Road To Hell:Specify the design & accept the performance"-Bruno Putzeys]
  Reply With Quote
Old 16th January 2011, 08:22 PM   #10
Zoran is offline Zoran  Serbia
diyAudio Member
 
Join Date: Jan 2004
Location: Belgrade
+
__________________
###
  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
Using The Tektronix 575 Curve Tracer Mark A. Gulbrandsen Solid State 29 21st May 2012 07:01 PM
curve tracer? maxpou Solid State 4 24th October 2009 05:29 PM
Virtual Tek 576/577 curve tracer in EWB V10 jackinnj Equipment & Tools 0 1st March 2007 01:41 PM
Anyone got a tube curve tracer for sale? jazzyjoepass Swap Meet 0 26th August 2004 05:24 AM
FS: tektronix 575 curve tracer SQ Kid Swap Meet 3 11th July 2004 04:22 PM


New To Site? Need Help?

All times are GMT. The time now is 10:31 AM.


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