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What do the terms AC and DC mean?

stabilizator 46821 23
This content has been translated » The original version can be found here
• The terms AC and DC refer to electric current. Indirectly, also tensions.

DC - direct current - means direct current. In theory, it is a power supply whose parameters are constant over time. Most often we say that about all sources that give a constant voltage. However, no one can guarantee that the output voltage, e.g. from the power supply, will be e.g. 12.13454V all the time. It can fluctuate or slightly change under the influence of the current consumption and the ambient temperature. In addition, the voltage coming from the power supply may have some ripples resulting from imperfect filtration (e.g. unstabilized power supply and also impulse power supply). It may turn out that the supply voltage is variable (to an extent not important from the point of view of the receiver).

Therefore, the "utility" definition of direct current is a bit broader - it is required not to change its direction. That is why we can name the voltage at the terminals of e.g. a battery, which is first 14.4V, and then slowly decreases due to discharge. Direct current can also be called a power supply from a DC generator driven by a wind turbine, the output voltage of which varies, for example, from 4V to 11V, depending on the current strength of the wind. A photovoltaic panel can be a similar DC source.

AC - alternating current - means alternating current, and more often periodic alternating current, it is one whose value changes in an intended and deterministic manner, i.e. sinusoidal. However, two subgroups can be distinguished here:
- alternating current, i.e. one whose value changes but does not change its direction (does not cross zero)
- alternating current, i.e. a variable whose value changes the sign (passes through zero)

In the Anglo-Saxon literature, the term AC is used to denote the latter type of current, i.e. alternating current. Alternating current can be called all non-zero waveforms that contain ripple or other distortions - that is, what I classified above as DC, because we look at what these waveforms should be intended for. It is difficult to set an unambiguous border, therefore a certain, customary classification has been adopted here. Mains supply 230V 50Hz belongs to AC. The AC supply allows the operation of e.g. induction motors or transformers.

"Author: Michał Kurzela / Futrzaczek"
"Correction: stabilizer"

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stabilizator
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stabilizator wrote 87 posts with rating 198, helped 0 times. Been with us since 2020 year.
Level 38
Lots of inaccuracies.
In my opinion, the text should be redrafted after consultation.
• Freddy
Level 43
Lots of inaccuracies.
• 398216 Usunięty
Level 43
The text (in my opinion) translated with a translator with a slight Author's correction - instead of writing (or rather pasting the translation) it would be better to paste the link to the original.
Level 38
I think so too.
E.g.:
stabilizator wrote:
AC - alternating current - means alternating current.
It's the one that value changes intentionally and deterministically, that is, for example, sinusoidal.
• Freddy
Level 43
The second is:
- AC, i.e. alternating current means (ignoring that it was alternate current) alternating current.
the third is:
- alternating current is current periodically changing in which the instantaneous values have alternating positive and negative values.
• stabilizator
Editor
Delving into seemingly simple issues often leads to a surprising discussion.
The topics in the guide section are open and this gives the opportunity to jointly expand the content by people with practical experience and knowledge in a given topic.
Level 38
So, Dear Editor, we have permission for further comments.
stabilizator wrote:
That is why we can name the voltage at the terminals of e.g. a battery, which is first 14.4V, and then slowly decreases due to discharge.

14.4 V could be the voltage on the acid battery during charging.
The voltage of such a fully charged battery is approximately 12.7 volts.
• stabilizator
Editor
I think that there is no permission or prohibition here, this is an open topic and everyone can express their opinion on the forum, but from my point of view it is worth sticking to the original topic as much as possible.

OK, my opinion is that it is worth discussing AC / DC because, depending on the specifications of the circuit, these terms may have slightly different meanings. However, I would like to avoid overshooting the topic and losing the main plot.

So in turn:

I think so too.
E.g.:
stabilizator wrote:
AC - alternating current - means alternating current.
It's the one that value changes intentionally and deterministically, that is, for example, sinusoidal.

So we have some assumptions about the system, e.g. the inverter output where it will be at the AC output, and it is a deterministic change, e.g. a 50Hz sine with a specific RMS voltage.

Freddy wrote:
The second is:
- AC, i.e. alternating current means (ignoring that it was alternate current) alternating current.
the third is:
- alternating current is current periodically changing in which the instantaneous values have alternating positive and negative values.

Alternating current is alternating current, but not all alternating current has to be alternating, so alternating current is a more general term.

So, Dear Editor, we have permission for further comments.
stabilizator wrote:
That is why we can name the voltage at the terminals of e.g. a battery, which is first 14.4V, and then slowly decreases due to discharge.

14.4 V could be the voltage on the acid battery during charging.
The voltage of such a fully charged battery is approximately 12.7 volts.

This voltage of 14.4V and the battery is just an example, there is no indication whether it is a lead-acid battery, it could be e.g. a battery consisting of 4 Li-ion cells with a current voltage of 3.6V. However, what you mention, i.e. the voltage in the system with a battery charged to 14.4V, and then the voltage drop to 12.7V, is also an example of an alternating waveform, but in most cases we will define the power supply of such a system as DC - direct voltage, not variable voltage (although in reality changes over time).
• Freddy
Level 43
stabilizator wrote:
Alternating current is alternating current, but not all alternating current has to be alternating, so alternating current is a more general term.
You are wrong - alternating current is current periodically changeable.
Definition from a high school textbook
Quote:
Alternating Current (AC) is a special type of periodically alternating current in which the instantaneous values have alternating positive and negative values.
They change with a certain frequency and periodically. A desired parameter is also a constant component with a value of zero. Most often it occurs in the form of a sinusoidal current.
Level 38
stabilizator wrote:
This voltage of 14.4V and the battery is just an example, there is no indication whether it is a lead-acid battery, it could be e.g. a battery consisting of 4 Li-ion cells with a current voltage of 3.6V.

Of course, you are right.
stabilizator wrote:
AC - alternating current - means alternating current. It's one whose value changes intentionally and deterministically

According to definition:
Alternating current - electric current for which the value of the intensity changes over time by any means .

So not deterministically - quite the opposite.
Where did you get this term to describe the current?
• atom1477
Level 43
English AC is alternating current only and exclusively.
Not generally "fickle".
Only commutative, that is, + and - alternating.
Level 38
atom1477 wrote:

English AC is alternating current only and exclusively.

Wechselspannung in German - also.
• stabilizator
Editor
stabilizator wrote:
This voltage of 14.4V and the battery is just an example, there is no indication whether it is a lead-acid battery, it could be e.g. a battery consisting of 4 Li-ion cells with a current voltage of 3.6V.

Of course, you are right.
stabilizator wrote:
AC - alternating current - means alternating current. It's one whose value changes intentionally and deterministically

According to definition:
Alternating current - electric current for which the value of the intensity changes over time by any means .

So not deterministically - quite the opposite.
Where did you get this term to describe the current?

In fact, an alternate will fit better here, I change, thanks.
• CYRUS2
Level 42
AC is an idiomatic phrase meaning both alternating voltage and current.
It is an accepted international term.
Voltage 230V AC.
Current 10A AC

Some used it thoughtlessly and it came out of stupidity.
/ voltage of 50V alternating current /
Standard 60364-4-41 2000:
As if someone wrote, I ate a "hot dog".
They improved in the new standard.

DC - Direct current is also an idiomatic phrase.
• Freddy
Level 43
Quote:
Alternating current, abbreviation AC, flow of electric charge that periodically reverses. It starts, say, from zero, grows to a maximum, decreases to zero, reverses, reaches a maximum in the opposite direction, returns again to the original value, and repeats this cycle indefinitely. The interval of time between the attainment of a definite value on two successive cycles is called the period, the number of cycles or periods per second is the frequency, and the maximum value in either direction is the amplitude of the alternating current.

Direct current, abbreviation DC, flow of electric charge that does not change direction. Direct current is produced by batteries, fuel cells, rectifiers, and generators with commutators.

¬ródło Encyclopedia Britanica
• CYRUS2
Level 42
Freddy wrote:
Quote:
Alternating current, abbreviation AC, flow of electric charge that periodically reverses ......

Source Encyclopedia Britanica

Texts in another language are not translated.
Translations are done.
Lest it turn out that I ate a "hot dog".
• Rafikusa
Level 17
atom1477 wrote:

English AC is alternating current only and exclusively.

Wechselspannung in German - also.

But that is already a term for tension.

The term Wechselstrom is used on a daily basis.
• atom1477
Level 43
But the most important thing is that it is commutative, not variable.
• User removed account
Level 1
• atom1477
Level 43
Awyrdonyt wrote:
So what does AC / DC mean?
AC / DC can mean a device that converts alternating current to direct current. It can be a power supply, it can be a converter, although in this case the processes of changing the current and voltage are multiple.

You forgot the most important thing. Possibility of power supply in both AC and DC.

Awyrdonyt wrote:
AC / DC - is also an Australian rock band (they play electric guitars) founded in 1973. You can read about the band on Wikipedia or on thematic forums devoted to music.

It doesn't matter because it's just the name of the band.
There are much more used names, and it does not prove anything.
• User removed account
Level 1
• atom1477
Level 43
They appear, but not on AC adapters, Only on receivers. There used to be more of it, when transformer plug-in power supplies were still used. Devices powered from them often had AC / DC recording, because they had rectifier bridges in them.
These were some shavers, modems, etc.
I even have a charger for an old phone on the transformer itself.
So the phone was accepting AC. And surely it could also be DC, so it could have the word AC / DC in the manual.
• ken-wawa
Level 12
How do you say alternating current in English? Variable current? What is the term used?