connecting DC voltage to a current circuit

[fgonz007]

I know this shouldn't be done by am trying to understand the "why" of it. Will the dc in the current affect the sine wave of the CT circuit?

Thanks!

 

[jghrist]

DC will saturate the core. I'm curious as to the "why" of doing it.

 

[fgonz007]

How will that affect relay operation? Will it cause inadvertent trips?

 

[marks1080]

You would likely short out your battery too. Either through the low burden CT itself or the low burden input it is connected to.

DC voltage will offset an AC voltage as well. This could look similar to a 2nd harmonic.

As long as you properly fuse your DC circuits you shouldn't cause any lasting damage. Maybe an inadvertant trip or two along the way.

 

[ScottyUK]

The secondary current will not be a scaled representation of the primary current. Depending on the CT function, and how it is interconnected connected to other CTs, and on how the relay behaves with DC at its input, it could conceivably cause inadvertent trips or prevent a trip when it should.

How did you plan on introducing DC into a CT circuit? And did you post this question elsewhere too? That tends to be frowned upon because it fragments discussion.

 

[fgonz007]

I don't intend on doing this. I found it as a wiring mistake and then realized I didn't know the "why". I did post in two places because I wasn't sure what subject it would fit under

 

[stevenal]

Might want to demagnetize the CT after the wiring is corrected.

 

[LiteYear]

To save others the time, this has been answered here as well:

http://www.eng-tips.com/viewthread.cfm?qid=357925

 

[waross]

You may gain a better overall understanding by studying magnetic amplifier theory.

Bill
--------------------
"Why not the best?"
Jimmy Carter