# "Continuous" current

#### suzuki

Joined Aug 10, 2011
119
I am just wondering what is the precise definition of continuous current? I did a quick google, and some sources imply that this is a dc current but I'm not confident that this is correct.

Does it actually mean we have current flow all the time? i.e. The current is discontinuous when its equal to zero? Thanks.

#### Ron H

Joined Apr 14, 2005
7,014
I am just wondering what is the precise definition of continuous current? I did a quick google, and some sources imply that this is a dc current but I'm not confident that this is correct.

Does it actually mean we have current flow all the time? i.e. The current is discontinuous when its equal to zero? Thanks.
What is the context? Give us an example.

#### strantor

Joined Oct 3, 2010
5,291
continuous would be steady. I.e. 5A flowing for 10 minutes, never going above 5.001A or below 4.999A. "discontinuous" I suppose would be "about" 5A flowing for 10 minutes, sometimes going up to 8A and sometimes down to 2A. All these numbers are made up, just for example.

#### wmodavis

Joined Oct 23, 2010
739
Mirriam-Webster dictionary
Definition of CONTINUOUS

: marked by uninterrupted extension in space, time, or sequence : continuing without intermission or recurring regularly after minute interruptions

#### suzuki

Joined Aug 10, 2011
119
What is the context? Give us an example.
Well for example, I can see that an ac current through a single diode rectifier could be called discontinuous since the negative cycles are zero for some time. However, if there was a full bridge rectifier, is that considered to be a continuous waveform?

As a counterexample to the above two posters, what about a sinusoidal signal? This is continuous yet the value varies. You could argue there it has an RMS value, but then I thought of the example of a square wave, where in my mind, is discontinuous.

#### ErnieM

Joined Apr 24, 2011
8,046
Well for example, I can see that an ac current through a single diode rectifier could be called discontinuous since the negative cycles are zero for some time. However, if there was a full bridge rectifier, is that considered to be a continuous waveform?

As a counterexample to the above two posters, what about a sinusoidal signal? This is continuous yet the value varies. You could argue there it has an RMS value, but then I thought of the example of a square wave, where in my mind, is discontinuous.
I would call the current through a single diode rectifier continuous. It doesn't have to be a simple DC signal.

However without a context we're just playing word games.

#### tpny

Joined May 6, 2012
216
Maybe it's referring to the power source being continuous as opposed to chopped (on/off/on/off...)

#### Ron H

Joined Apr 14, 2005
7,014
Well for example, I can see that an ac current through a single diode rectifier could be called discontinuous since the negative cycles are zero for some time. However, if there was a full bridge rectifier, is that considered to be a continuous waveform?

As a counterexample to the above two posters, what about a sinusoidal signal? This is continuous yet the value varies. You could argue there it has an RMS value, but then I thought of the example of a square wave, where in my mind, is discontinuous.
I think current through a bridge would be considered discontinuous, although that is arguable. Certainly it is discontinuous if the bridge has a smoothing cap on the output.
A sinusoidal signal would be considered to be continuous, even though it goes through zero. A square wave which is at zero for a finite portion of the period would be discontinuous.

#### THE_RB

Joined Feb 11, 2008
5,438
Definition of continuous itself means it does not stop, however something continuous could vary. I think an AC sinewave in current terms is not "continuous" as at two points int he cycle the current must stop and reverse. A DC sinewave on the other hand can be "continuous current" as it just varies, but never stops.

#### GetDeviceInfo

Joined Jun 7, 2009
1,729
I've used the word 'continous' to describe things over the years, but never with current (that I remember). Even if the playing field was well established and the term defined, it would change in the next scenario. I wouldn't worry about it unless it's an exam question, then go with the instructors version.