Previous in Forum: Power Grid Question   Next in Forum: Need 8 to 15 Volts from DC Motor
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
9 comments
Rate Comments: Nested
Anonymous Poster

DC Current & CT

05/17/2010 5:12 AM

I will be thankful if any one can help me out of this. How DC current is sensed by CT.
Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
JohnDG
Guru
United Kingdom - Member - Not a New Member Hobbies - Musician - New Member Hobbies - Fishing - New Member

Join Date: May 2006
Location: Reading, Berkshire, UK. Going under cover.
Posts: 9684
Good Answers: 468
#1

Re: DC current & CT

05/17/2010 7:01 AM

CD current can be sensed by a Current Transformer only when it's value changes. Other devices (such as a Hall Effect probe) may be used for "non-invasive" DC current measurement.

__________________
 "Love justice, you who rule the world" - Dante Alighieri
Reply
Anonymous Poster
#2

Re: DC current & CT

05/17/2010 7:04 AM

hi Guest,,,

as far as I know that the CTs are based on the phenomena of electric induction according to Faraday's law, this means that the CTs can't be applied to the DC current .

Thanks................
Reply
Ali18
Power-User

Join Date: May 2008
Posts: 136
Good Answers: 2
#3
In reply to #2

Re: DC current & CT

05/17/2010 7:07 AM

hi Guest,,,

as far as I know that the CTs are based on the phenomena of electric induction according to Faraday's law, this means that the CTs can't be applied to the DC current .

Thanks................

__________________
 Just live and .. Learn!!
Reply
kvsridhar
Guru
India - Member - New Member

Join Date: Sep 2009
Location: Temporarily at Ashburn, VA
Posts: 2744
Good Answers: 164
#4

Re: DC current & CT

05/17/2010 7:41 AM

i have come across DC current transformers in a large chemical plant. Not having any need for such things myself, i did not pursue the subject, just remember faintly that the DC saturated the core and a known AC signal was superimposed .. so on. Well, the DC CT is well documented in many websites, and it may be worth while for you to study this patent..

DC CT Patent

__________________
 Nothing worthwhile can ever be taught, it can only be learnt.
Reply
Anonymous Poster
#5

Re: DC Current & CT

05/17/2010 11:56 PM

Thanks all for the reply. My question is how DC current is measured by CT in DCDB.
Reply
kvsridhar
Guru
India - Member - New Member

Join Date: Sep 2009
Location: Temporarily at Ashburn, VA
Posts: 2744
Good Answers: 164
#6
In reply to #5

Re: DC Current & CT

05/18/2010 12:13 AM

There are many suppliers of DC CTs ... you can google for one in your region. Here is one...

amprobe

__________________
 Nothing worthwhile can ever be taught, it can only be learnt.
Reply
kvsridhar
Guru
India - Member - New Member

Join Date: Sep 2009
Location: Temporarily at Ashburn, VA
Posts: 2744
Good Answers: 164
#9
In reply to #5

Re: DC Current & CT

05/20/2010 4:04 AM

Dear guest, i am sure you are busy with many other things, and haven't had the time to check out replies on this thread. i guess if you are not registered, there is no way CR4 can send you a mail telling you that there is a response to your thread. Well, as and when you do see this thread again ... will you please check the patent i mention ? and having read it, if you still don't understand, maybe some more experts will get involved and explain ? Good for everyone who do not know this subject.

__________________
 Nothing worthwhile can ever be taught, it can only be learnt.
Reply
PWSlack
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
Good Answers: 839
#7

Re: DC Current & CT

05/18/2010 4:20 AM

Transformers work on changing currents, so it isn't immediately obvious how a current transformer could ever give anything sensible when connected to a DC supply.

__________________
 "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Reply
kvsridhar
Guru
India - Member - New Member

Join Date: Sep 2009
Location: Temporarily at Ashburn, VA
Posts: 2744
Good Answers: 164
#8
In reply to #7

Re: DC Current & CT

05/18/2010 5:17 AM

i wouldn't have believed it if i hadn't seen it in operation.

It works on the principle of asssessing the saturation level of the core, by superimposing a known AC wave and then measuring the output. Fully explained here: DC CT Patent 4626777.pdf

__________________
 Nothing worthwhile can ever be taught, it can only be learnt.
Reply
Reply to Forum Thread
Have a Different Question?
9 comments
Copy to Clipboard

Users who posted comments:

Ali18 (1); Anonymous Poster (2); JohnDG (1); kvsridhar (4); PWSlack (1)

Previous in Forum: Power Grid Question   Next in Forum: Need 8 to 15 Volts from DC Motor

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Electrical Engineering:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (153 right now)
Show Members
Advertisement