blue voltage arrow from manual label wrong rotation

[judober]

I have two questions regartind the blue voltage from manual page 152:
first: I had to replace the node position to above when using this on a voltage source. Is there a general approach for a version that works with voltage sources as well as other bipoles?
second: The retation seems not to use the "smart" behavior of the element labels (see example). Can this behaviour be used?

\documentclass[class=report, ngerman,11pt,a4paper,tikz,]{standalone}
\usepackage[european, straightvoltages, americaninductors, betterproportions, nooldvoltagedirection]{circuitikz}
\begin{document}
\begin{tikzpicture}

\def\myvv#1#2{%
\draw [thin, blue, ->,]
(#1-Vfrom) .. controls (#1-Vcont1) and (#1-Vcont2).. (#1-Vto)
node [pos=0.5, above,	% Note compared to manual: below -> above
rotate=\ctikzgetdirection{#1}] at (#1-Vlab) {#2}; }

\draw (-30:3) [L, o-, l={\(L_{ab}\)}] to (-30:1.5) [V, -*, name=V1, l={\(\)}] to (-30:0);
\myvv{V1}{\(v_{12}\)}

\end{tikzpicture}%
\end{document}

Voltagesource2.pdf

[Rmano]

Inline image:

[Rmano]

This is quite complex, really. One of the problem is that the "smart" label positioning works only for labels, not for voltages --- I have prepared a simple example here (attached below). Notice that the "normal" voltages labels, called $v_n$, are always straight, even if I use the bipole/is voltage=false trick. Smart voltage label would be nice, but it's a lot of work.

To get the anchor used by the label, you can use \ctikzgetanchor{}{} as in the file below; but now, even in this case, the information reported by \ctikzgetdirection{} seems wrong (by 180 degrees) in this case. mmm... Will look at it.

\documentclass[class=report, 11pt,a4paper,tikz,border=5pt]{standalone}
\usepackage[european, straightvoltages, americaninductors, betterproportions, nooldvoltagedirection]{circuitikz}
\begin{document}
\begin{tikzpicture}

\def\myvv#1#2{%
\draw [thin, blue, ->,]
(#1-Vfrom) .. controls (#1-Vcont1) and (#1-Vcont2).. (#1-Vto)
node [pos=0.5, anchor=\ctikzgetanchor{#1}{Vlab},
rotate=\ctikzgetdirection{#1}] at (#1-Vlab) {#2}; }

% Normal voltages
\begin{scope}[yshift=2cm]
\draw (-30:3) to[L, o-, l={\(L_{ab}\)}] (-30:1.5) to [V, -*, name=V1, v=$v_n$,]  (-30:0);
\end{scope}

% extended voltage
\draw (-30:3) to[L, o-, l={\(L_{ab}\)}, v=$v_{ab}$] (-30:1.5) to[V, -*, name=V1, ] (-30:0);
\myvv{V1}{\(v_{12}\)}

% extended voltage, no special source treatment
\begin{scope}[yshift=-2cm]
\draw (-30:3) to[L, o-, l={\(L_{ab}\)}] (-30:1.5) to[V, -*, name=V1, v, bipole/is voltage=false]  (-30:0);
\myvv{V1}{\(v_{12}\)}
\end{scope}

% normal voltage, no special source treatment
\begin{scope}[yshift=-4cm]
\draw (-30:3) to[L, o-, l={\(L_{ab}\)}] (-30:1.5) to[V, -*, name=V1, v=$v_n$, bipole/is voltage=false]  (-30:0);
\end{scope}
\end{tikzpicture}%
\end{document}

[Rmano]

Anyway, in this case, you have an easy solution: you can use the label-positioning options of TikZ for placing your voltage label. Maybe you need to leave a manual knob for above / below, but what about this?

\documentclass[class=report, 11pt,a4paper,tikz, border=4pt]{standalone}
\usepackage[european, straightvoltages, americaninductors, betterproportions, nooldvoltagedirection]{circuitikz}
\newcommand{\myvv}[3][below]{%
    \draw [thin, blue, ->,] (#2-Vfrom) -- (#2-Vto) node [pos=0.5, #1, sloped] {#3}; 
}
\begin{document}
\begin{tikzpicture}

\draw (-30:3) to[L, o-, l=$L_{ab}$, v, name=L1] (-30:1.5) to[V, -*, name=V1,] (-30:0);
\myvv{V1}{$v_{12}$}
\myvv[above]{L1}{$v_{ab}$}

\end{tikzpicture}%
\end{document}

PS given that the voltages are straight, you can do them with a line, no need to use a Bezier curve. I also have removed ngerman from the option, it gave an "unused warning" (probably you use babel in your real document...).

[judober]

Yes, this is quite good. Still not perfect in some cases:

\documentclass[class=report, 11pt,a4paper,tikz, border=4pt]{standalone}
\usepackage[european, straightvoltages, americaninductors, betterproportions, nooldvoltagedirection]{circuitikz}
\newcommand{\myvv}[3][below]{%
	\draw [thin, blue, -latex,] (#2-Vfrom) -- (#2-Vto) node [pos=0.5, #1, sloped] {#3}; 
}
\begin{document}
	\begin{tikzpicture}
		
		\draw (90:3) to[L, o-, l=$L_{ab}$, v, name=L1] (90:1.5) to[V, -*, name=V1,] (-30:0);
		\myvv[above]{V1}{$v_{12}$}
		\myvv{L1}{$v_{ab}$}
		
	\end{tikzpicture}%
\end{document}

Voltagesource2.pdf

Additinally:
Is it possible to use the default circuitikz arrow tips?
And can I move the voltage arrow to the other side of the element? E.g. is there something like xx-Vfrom_back?

[Rmano]

Yes, this is quite good. Still not perfect in some cases:

Yes; technically it is doing what you ask (voltage label sloped) but in this case is not what you want. You need some manual adjustment here, probably with \rotatebox

Is it possible to use the default circuitikz arrow tips?

Unfortunately, they are not really arrowhead. But you can simulate them quite well with a -Triangle[], look here: https://tex.stackexchange.com/a/549354/38080

And can I move the voltage arrow to the other side of the element? E.g. is there something like xx-Vfrom_back?

That should work with adding v_ or v^ to the options.

\documentclass[class=report, 11pt,a4paper,tikz, border=4pt]{standalone}
\usepackage[european, straightvoltages, americaninductors, betterproportions, nooldvoltagedirection]{circuitikz}
\newcommand{\myvv}[3][below]{%
	\draw [thin, blue, -latex,] (#2-Vfrom) -- (#2-Vto) node [pos=0.5, #1, sloped] {#3};
}
\begin{document}
	\begin{tikzpicture}

		\draw (90:3) to[L, o-, l=$L_{ab}$, v, name=L1] (90:1.5) to[V, -*, v_, name=V1,] (-30:0);
                \myvv{V1}{\rotatebox{90}{$v_{12}$}}
                \myvv{L1}{\rotatebox{90}{$v_{ab}$}}

	\end{tikzpicture}%
\end{document}

(PS: you can do a screenshot and paste the image directly in the answer to have it inline...)

[judober]

Ok thanks a lot. This works for me.

[Rmano]

Thanks! I will try to tackle the main problem also --- there is something pesky in the code (this is why is marked experimental in the manual!). So I'll leave this open for now.

[Rmano]

So... I finally think this is not an error. Voltage labels are always drawn straight, and the correct way to mimic (but in blue) the normal positioning is not using rotate=\ctikzgetdirection{#1} at all.

\def\myvv#1#2{\draw [thin, blue, ->,]
     (#1-Vfrom) .. controls (#1-Vcont1) and (#1-Vcont2).. (#1-Vto)
     node [anchor=\ctikzgetanchor{#1}{Vlab}] at (#1-Vlab) {{#2}}; }

ctikzgetdirection is the direction of the bipole, which is correctly reported as 150 (degree); the probelm is that it is not using in the voltage text positioning but for determining the anchor.

So it is not really a bug, maybe a lack of feature ;-)

[judober]

Maybe someone can use this:
I advanced this a little to get something similar to the smart label behaviour. However, one still has to chose between two versions depending on if v oder v_ is chosen (the voltage source has confusingly the inverse behaviour).
I didn't know the limits for horizontal text in the original implementation so the text is only horizontal for vertical lines.

\documentclass[class=report, 11pt,a4paper,tikz, border=4pt]{standalone}
\usepackage[european, straightvoltages, americaninductors, betterproportions, nooldvoltagedirection]{circuitikz}

\newcounter{ang}

\newcommand{\vcross}[3]{
	\draw [thin, blue, -Triangle,] (#2-Vfrom) .. controls (#2-Vcont1) and (#2-Vcont2).. (#2-Vto) node [pos=0.5, #1, sloped] {#3};
}

\newcommand{\vhorz}[2]{
	\draw [thin, blue, -Triangle,] (#1-Vfrom) .. controls (#1-Vcont1) and (#1-Vcont2).. (#1-Vto)
	node [anchor=\ctikzgetanchor{#1}{Vlab}] at (#1-Vlab) {{#2}};
}

\newcommand{\myvv}[2]{
	\setcounter{ang}{\ctikzgetdirection{#1}}
	\ifnum \value{ang} < 90 {
		\vcross{below}{#1}{#2}
	}
	\else {\ifnum \value{ang} = 90 {
		\vhorz{#1}{#2}
	}
	\else {\ifnum \value{ang} < 270 {
		\vcross{above}{#1}{#2}
	}
	\else {\ifnum \value{ang} = 270 {
		\vhorz{#1}{#2}
	}
	\else{
		\vcross{below}{#1}{#2}
	}\fi}\fi}\fi}\fi
}

\newcommand{\myvvf}[2]{	% fliped version
	\setcounter{ang}{\ctikzgetdirection{#1}}
	\ifnum \value{ang} < 90 {
		\vcross{above}{#1}{#2}
	}
	\else {\ifnum \value{ang} = 90 {
		\vhorz{#1}{#2}
	}
	\else {\ifnum \value{ang} < 270 {
		\vcross{below}{#1}{#2}
	}
	\else {\ifnum \value{ang} = 270 {
		\vhorz{#1}{#2}
	}
	\else{
		\vcross{above}{#1}{#2}
	}\fi}\fi}\fi}\fi
}

\begin{document}
	\begin{tikzpicture}
		
		\draw (30:4) to[L, o-, l=$L_{ab}$, v, name=L1] (30:2) to[V, -*, v, name=V1,] (0:0);
		\myvvf{V1}{$v_{12}$}
		\myvv{L1}{$v_{longName}$}
		
	\end{tikzpicture}%
\end{document}

[Rmano]

Hmmm... this can be transformed to an enhancement request to export also label direction (the label position is already there, giving that the label node is accessible).

[Rmano]

Added in PR #452 :

[judober]

So, one question: what is the difference between annotation and voltage label? does it make sense to use an annotation instead of the voltage?

[Rmano]

An annotation is just like a label, only it appears on the other side by default and it can be styled differently from the label.
Voltage labels, on the other side, are very different; they normally add an arrow or the "+" "-" sign, they are always horizontal, etc.
The usage depends on what you like, basically.

[judober]

I came around playing with this a bit. However, \ctikzgetrotation doesn't seem to work? The example below errors with Unknown function V1label and the same for L1label. I use circuitikz 1.2.5.

\documentclass[class=report, 11pt,a4paper,tikz, border=4pt]{standalone}
\usepackage[european, straightvoltages, americaninductors, betterproportions, nooldvoltagedirection]{circuitikz}

\newcommand{\vsmart}[3]{
	\draw [thin, blue, -Triangle,] (#2-Vfrom) .. controls (#2-Vcont1) and (#2-Vcont2).. (#2-Vto) node [pos=0.5, anchor=\ctikzgetanchor{#2}{Vlab}, rotate=\ctikzgetrotation{#2label}] {{#3}};
}

\begin{document}
	\begin{tikzpicture}
		
		\draw (30:4) to[L, o-, l=$L_{ab}$, v, name=L1] (30:2) to[V, -*, v={\(v_{12}\)}, name=V1,] (0:0);
		\vsmart{below}{V1}{$v_{12}$}
		\vsmart{below}{L1}{$v_{longName}$}

	\end{tikzpicture}%
\end{document}

[Rmano]

Will look into it

[Rmano]

Well, the easy thing is that it's called \ctikzgetdirection ;-). But still, the rotate key does not like it, I have to investigate.

[judober]

Well, I tried \ctikzgetdirection too but it didn't work. In the manual on page 153 however (in the screenshot obove too) the text says

since1.2.5 you can access the label rotation using with the command \ctikzgetrotation{nodename}

and so I thought this is supposed to work...

[Rmano]

Yes, that is a typo, look at the code. For the more fundamental problem (the erroring out) I have an idea of what's happening, but I have to check and I have no time right now... I hope to solve it asap. It seems an expansion problem in the TikZ parameter list.

[Rmano]

Ok, found the problem. There is no label defined for V1, so no direction macro.

documentclass[class=report, 11pt,a4paper,tikz, border=4pt]{standalone}
\usepackage[european, straightvoltages, americaninductors, betterproportions, nooldvoltagedirection]{circuitikz}

\newcommand{\vsmart}[3]{
	\draw [thin, blue, -Triangle,] (#2-Vfrom) .. controls (#2-Vcont1) and (#2-Vcont2).. (#2-Vto) node [pos=0.5, anchor=\ctikzgetanchor{#2}{Vlab}, rotate=\ctikzgetdirection{#2label}] {{#3}};
}

\begin{document}
	\begin{tikzpicture}
		
		\draw (30:4) to[L, o-, l=$L_{ab}$, v, name=L1] (30:2) to[V, -*, v={\(v_{12}\)}, name=V1, l=~] (0:0);
		\vsmart{below}{V1}{$v_{12}$}
		\vsmart{below}{L1}{$v_{longName}$}

	\end{tikzpicture}%
\end{document}

I think it's commented in the manual somewhere... yes:

[judober]

Ok, this is as far as I have come with this:

\documentclass[class=report, 11pt,a4paper,tikz, border=4pt]{standalone}
\usepackage[european, straightvoltages, americaninductors, betterproportions, nooldvoltagedirection]{circuitikz}[
bipoles/label=~,
]

\usepackage{xifthen}
\usetikzlibrary{math}
	
\newcommand{\vhorz}[2]{
	\draw [thin, blue, -Triangle,] (#1-Vfrom) .. controls (#1-Vcont1) and (#1-Vcont2).. (#1-Vto)	node [anchor=\ctikzgetanchor{#1}{Vlab}] at (#1-Vlab) {{#2}};
}

\newcommand{\dpCcoord}{}	% Center-Coord
\newcommand{\dpVcoord}{}	% Label-Coord

\newcommand{\vcrossauto}[2]{
	\renewcommand{\dpCcoord}{(#1.center)}
	\renewcommand{\dpVcoord}{(#1voltage.center)}
	\tikzmath{
		coordinate \dpC, \dpV;
		\dpC = \dpCcoord;
		\dpV = \dpVcoord;
		if \dpCy < \dpVy then{
			{\draw [thin, blue, -Triangle,] (#1-Vfrom) .. controls (#1-Vcont1) and (#1-Vcont2).. (#1-Vto) node [pos=0.5, above, sloped] {#2};};
		} else {
			{\draw [thin, blue, -Triangle,] (#1-Vfrom) .. controls (#1-Vcont1) and (#1-Vcont2).. (#1-Vto) node [pos=0.5, below, sloped] {#2};};
		};
	}
}

\newcommand{\dprot}{}	% Label-Rotation

\newcommand{\varr}[2]{
	\renewcommand{\dprot}{\ctikzgetdirection{#1label}}
	\ifthenelse{\dprot = 0}{
		\vhorz{#1}{#2}
	}{
		\vcrossauto{#1}{#2}
	}
}

\newcommand{\ihorz}[2]{
	\draw [red, thin, -{Triangle[]}]
	([shift={(\ctikzgetdirection{#1}:-0.06)}] #1-Ipos) --
	([shift={(\ctikzgetdirection{#1}:0.06)}] #1-Ipos)
	node [anchor=\ctikzgetanchor{#1}{Ilab}] at (#1-Ipos) {{#2}};
}

\newcommand{\icross}[3]{
	\draw [red, thin, -{Triangle[]}]
	([shift={(\ctikzgetdirection{#2}:-0.06)}] #2-Ipos) --
	([shift={(\ctikzgetdirection{#2}:0.06)}] #2-Ipos)
	node [pos=0.5, #1, sloped] {#3};
}

\newcommand{\icrossauto}[2]{
	\renewcommand{\dpCcoord}{(#1-Ipos)}
	\renewcommand{\dpVcoord}{(#1current.center)}
	\tikzmath{
		coordinate \dpC, \dpI;
		\dpC = \dpCcoord;
		\dpI = \dpVcoord;
		if \dpCy < \dpIy then{
			{\icross{above}{#1}{#2};};
		} else {
			{\icross{below}{#1}{#2};};
		};
	}
}

\newcommand{\iarr}[2]{
	\renewcommand{\dprot}{\ctikzgetdirection{#1label}}
	\ifthenelse{\dprot = 0}{
		\ihorz{#1}{#2}
	}{
		\icrossauto{#1}{#2}
	}
}


\begin{document}
	\begin{tikzpicture}
		
		\draw (150:4) to[L, o-, l=$L_{ab}$, v=v, name=L1, i=~] (150:2) to[V, -*, v_={\(v_{12}\), l=~, i=~}, name=V1] (0:0);
		\varr{V1}{$v_{12}$}
		\varr{L1}{$v_{longName}$}
		\iarr{V1}{$i$}
		\iarr{L1}{$i$}
		
	\end{tikzpicture}%
\end{document}

This already works quite well, I added a red current too.
Two question: can i globally define default values for l,v,i so that I do not have to define them for every bipole (tried with bipoles/label=~ which had no effect). And: the current direction comes from the dipoles direction which can be wrong. Can I get the direction of the current arrow somehow? (Ifrom and Ito seem to be less useful here as I only want the arrow tip)

[Rmano]

About your second question, there is no a "default label" for components --- and the anchors can be generated only if we have to typeset a label (this is different for i, v, f where you can just define them and have the anchors for the symbol; but notice that to have the anchors for the voltage labels, for example, you need to have the label with a least v=~ or v=\null (\null is \hbox{}, a void box).

You can always define a style for the components you use:

\tikzset{
    L+/.style={L, v=\null, i=~, f, l=~, a=~}, % use \null or ~ whatever you prefer
    V+/.style={V, v=~, i=~, f, l=~, a=~},
}

and then use them like (in your example):

\draw (150:4) to[L+, o-, l=$L_{ab}$, name=L1,] (150:2) to[V+, -*, v_={\(v_{12}\)}, name=V1] (0:0);

so that you can always override the direction or the label if you want (like to[L+, v<, ...] ...).

For the current direction, no, there is not a pre-defined function, but you can easily (well, after a bit of TikZ manual digging):

\newcommand{\darr}[1]{
        \pgfmathanglebetweenpoints{\pgfpointanchor{#1-Ifrom}{center}}{\pgfpointanchor{#1-Ito}{center}}
        \edef\myangletmp{\pgfmathresult}
        %\typeout{\myangletmp}
        \node [flowarrow, rotate=\myangletmp, color=green] at (#1-Ipos){};
}

and you can use them like

	\draw (150:4) to[L+, o-, l=$L_{ab}$, name=L1,i>_] (150:2) to[V+, -*, v_={\(v_{12}\)}, name=V1] (0:0);
	\varr{V1}{$v_{12}$}
	\varr{L1}{$v_{longName}$}
	\iarr{V1}{$i$}\darr{V1}
        \iarr{L1}{$i$}\darr{L1}

[Rmano]

BTW, adding something as every bipole add= style could be interesting... will think about it.

Doing that now will be quite a lot of work, because the bipoles are defined one by one and that will mean a lot of work. But if I (or some brave soul) come out to try to streamline it with a set of meta-macros, it could be done (and probably that will help also to solve #346). Lot of \expandafter I fear, so it will need to wait for a period when I have way less work in RL ;-)

[Rmano]

@judober if you want to match the arrow size (Not necessary I think, but...) you can find info here: https://tex.stackexchange.com/questions/549347/circuitikz-arrowhead

[judober]

I updated my code in case some one can use it. Thanks for your input.

\documentclass[class=report, 11pt,a4paper,tikz, border=4pt]{standalone}
\usepackage[european, straightvoltages, americaninductors, betterproportions, nooldvoltagedirection]{circuitikz}[
]

\usepackage{xifthen}
\usetikzlibrary{math}


\tikzset{
    L+/.style={L, v=~, i=~, f, l=~, a=~},
    V+/.style={V, v=~, i=~, f, l=~, a=~},
}


\newcommand{\vhorz}[3][blue]{
	\draw [thin, #1, -Triangle,] (#2-Vfrom) .. controls (#2-Vcont1) and (#2-Vcont2).. (#2-Vto)	node [anchor=\ctikzgetanchor{#2}{Vlab}] at (#2-Vlab) {{#3}};
}

\newcommand{\vcrossauto}[3][blue]{
	\tikzmath{
		coordinate \dpC, \dpV;
		\dpC = (#2.center);
		\dpV = (#2voltage.center);
		if \dpCy < \dpVy then{
			{\draw [thin, #1, -Triangle,] (#2-Vfrom) .. controls (#2-Vcont1) and (#2-Vcont2).. (#2-Vto) node [pos=0.5, above, sloped] {#3};};
		} else {
			{\draw [thin, #1, -Triangle,] (#2-Vfrom) .. controls (#2-Vcont1) and (#2-Vcont2).. (#2-Vto) node [pos=0.5, below, sloped] {#3};};
		};
	}
}


\newcommand{\varr}[3][blue]{
	\tikzmath{
		\dprot = \ctikzgetdirection{#2label};
		if \dprot == 0 then{
			{\vhorz[#1]{#2}{#3}};
		}else{
			{\vcrossauto[#1]{#2}{#3}};
		};
	}
}

\newcommand{\iarr}[3][red]{	%1. optional color, 2. Referenz to element, 3. label
        \pgfmathanglebetweenpoints{\pgfpointanchor{#2-Ifrom}{center}}{\pgfpointanchor{#2-Ito}{center}}
        \edef\myangletmp{\pgfmathresult}
        % \typeout{\myangletmp}
        \node [currarrow, rotate=\myangletmp, color=#1] at (#2-Ipos){};

        % Name not rotated -> label not rotated
        \pgfmathparse{notequal(\ctikzgetdirection{#2label},0)}
        \edef\namerottmp{\pgfmathresult}
        
        % rotate 180 if angle is between 90 and 270
        \pgfmathparse{\myangletmp + ifthenelse(and(\myangletmp>90,\myangletmp<270),180,0)}
        \edef\mylabangletmp{\pgfmathresult}
        % \typeout{\mylabangletmp}
        
        % placement above or below
        \tikzmath{
	        coordinate \dpC, \dpI;
	        \dpC = (#2-Ipos);
	        \dpI = (#2current.center);
	        if {\namerottmp} then {	
		        if \dpCy < \dpIy then{ %above
			        {\node [above, rotate=\mylabangletmp, #1] at (#2-Ipos) {#3};};
		        } else { %below
			        {\node [below, rotate=\mylabangletmp, #1] at (#2-Ipos) {#3};};
		        };
	        } else {	%not rotated -> use default position
		        {\node [anchor=\ctikzgetanchor{#2}{Ilab}, #1] at (#2-Ipos) {#3};};
	        };
        }
}


\begin{document}
	\begin{tikzpicture}
		
		\draw (130:4) to[L+, o-, l=$L_{ab}$, v=v, name=L1, i=i] (130:2) to[V+, -*, v_={\(v_{12}\)}, name=V1, i>_=~] (0:0);
		\varr[purple]{V1}{$v_{12}$}
		\varr{L1}{$v_{longName}$}
		\iarr{V1}{$i$}
		\iarr[green]{L1}{$i_{longName}$}
		
	\end{tikzpicture}%
\end{document}

[judober]

Actually, I just noticed that this does not work as I intended:
Using the definition L+ (or similar) always generates (normal) voltage and current arrows. I can change the defintion to

\tikzset{
    L+/.style={L, v, i, f, l, a},
    V+/.style={V, v, i, f, l, a},
}

that fixes this. But I depend on #2current.center and thus I need the invisible label.
For the voltage it might be possible to circumvent this by using the bipole-position and compare it with the arrow-position. But for the current I need #2current.center as the arrow does not change when using i_.
Is it possible to define an (invisible) currentlabel withouth drawing the current arrow (and the same for the voltage)?

[Rmano]

Not sure if I understand (could you make a small example?) Can't you use \ctikzgetanchor{#2}{Ilab} ?

[Rmano]

Anyway, for now no, there is no way to have the void label for v and i and f without the corresponding arrow. I can look into it, if I find an easy way to do it...

[judober]

Let's say I want only a current label for the first source and a voltage for the second. Using the definitions I get

\begin{document}
	\begin{tikzpicture}
		
		\draw (40:4) to[L+, o-, l=$L_{ab}$, name=L1] (40:2) to[V+, -*, name=V1] (0:0);
		\draw (130:4) to[L+, o-, l=$L_{ab}$, name=L2] (130:2) to[V+, -*, name=V2] (0:0);
		\draw (220:4) to[L+, o-, l=$L_{ab}$, name=L3] (220:2) to[V+, -*, name=V3] (0:0);

		\iarr{V1}{$i$}	% current for 1. voltage source
		\varr{V2}{$v$}	% voltage vor 2. voltage source

	\end{tikzpicture}%
\end{document}

So every voltage and current arrow (black) is present due to using L+, V+.

Using L and V instead errors:

\begin{document}
	\begin{tikzpicture}
		
		\draw (40:4) to[L, o-, l=$L_{ab}$, name=L1] (40:2) to[V, -*, name=V1] (0:0);
		\draw (130:4) to[L, o-, l=$L_{ab}$, name=L2] (130:2) to[V, -*, name=V2] (0:0);
		\draw (220:4) to[L, o-, l=$L_{ab}$, name=L3] (220:2) to[V, -*, name=V3] (0:0);

		\iarr{V1}{$i$}	% current for 1. voltage source
		\varr{V2}{$v$}	% voltage vor 2. voltage source

	\end{tikzpicture}%
\end{document}

I have to define v=~ etc for the dipoles I want currents and voltages for.

\begin{document}
	\begin{tikzpicture}
		
		\draw (40:4) to[L, o-, l=$L_{ab}$, name=L1] (40:2) to[V, -*, name=V1, i=~, l=~] (0:0);
		\draw (130:4) to[L, o-, l=$L_{ab}$, name=L2] (130:2) to[V, -*, name=V2, v=~, l=~] (0:0);
		\draw (220:4) to[L, o-, l=$L_{ab}$, name=L3] (220:2) to[V, -*, name=V3] (0:0);

		\iarr{V1}{$i$}	% current for 1. voltage source
		\varr{V2}{$v$}	% voltage vor 2. voltage source

	\end{tikzpicture}%
\end{document}

I still have the problem that the blue voltage arrow does not fully cancel out the black one. It would be nice if just defining v (and v_ ) would not only define the voltage arrow anchors (described in 5.8.1) but also an anchor for the voltage label position.

[Rmano]

Ok, I think I understand the problem. I will see if I can add the "label references" even when there is no label to print; it was not there because the idea is that when using a simple v then the user would take responsibility for everything (even the placement of the voltage label) and when using v=~ the user wanted the arrows/sign automatically set and just take responsibility for the voltage label.

I still thing you are trying to over-automatize it; for example, for the current I would do the following --- using the NewDocumentCommand to have two different optional argument --- and probably something similar for the voltages. Then I'll add the v wtc only when I need it, not to all components...

\documentclass[tikz]{standalone}
\usepackage{circuitikz}

\NewDocumentCommand{\iarr}{O{red} D(){below} m m}{% color, where, name, label
    \pgfmathanglebetweenpoints{\pgfpointanchor{#3-Ifrom}{center}}{\pgfpointanchor{#3-Ito}{center}}
        \edef\myangletmp{\pgfmathresult}
        %\typeout{\myangletmp}
        \node [currarrow, rotate=\myangletmp, color=#1 ] at (#3-Ipos){};
        \node [color=#1, rotate=\myangletmp, #2] at (#3-Ipos) {#4};
    }

\NewDocumentCommand{\varr}{O{blue} D(){below} m m}{% color, where, name, label
    \draw [thin, #1, -Triangle,] (#3-Vfrom) .. controls (#3-Vcont1) and (#3-Vcont2).. (#3-Vto)	node [midway, sloped,  #2] {#4};
    }

\begin{document}
	\begin{tikzpicture}
		\draw (40:4) to[L, o-, l=$L_{ab}$, name=L1] (40:2) to[V, -*, name=V1, i] (0:0);
		\draw (130:4) to[L, o-, l=$L_{ab}$, name=L2] (130:2) to[V, -*, name=V2, v] (0:0);
		\draw (220:4) to[L, o-, l=$L_{ab}$, name=L3] (220:2) to[V, -*, name=V3] (0:0);

                \iarr[blue]{V1}{$i$}	% current for 1. voltage source
                \iarr(above){V1}{$i$}	% current for 1. voltage source
                \varr(above){V2}{$v$}	% voltage vor 2. voltage source

	\end{tikzpicture}%
\end{document}

Anyway, I will open a enhancement ticket to track this.

[judober]

First of all thanks for showing me \NewDocumentCommand.
Regarding automatisation you are probably right. However, a problem I have with your proposal: When inverting the current direction, the current letter is turned upside down:

\begin{document}
	\begin{tikzpicture}
		
		\draw (40:4) to[L, o-, l=$L_{ab}$, name=L1] (40:2) to[V, -*, name=V1, i>] (0:0);
		\draw (130:4) to[L, o-, l=$L_{ab}$, name=L2] (130:2) to[V, -*, name=V2, v_] (0:0);
		\draw (220:4) to[L, o-, l=$L_{ab}$, name=L3] (220:2) to[V, -*, name=V3] (0:0);

		\iarr(above){V1}{$i$}	% current for 1. voltage source
		\varr(below){V2}{$v$}	% voltage vor 2. voltage source

	\end{tikzpicture}%
\end{document}

which can be fixed defining

\NewDocumentCommand{\iarr}{O{red} D(){below} m m}{% color, where, name, label
    \pgfmathanglebetweenpoints{\pgfpointanchor{#3-Ifrom}{center}}{\pgfpointanchor{#3-Ito}{center}}
        \edef\myangletmp{\pgfmathresult}
        %\typeout{\myangletmp}
        \node [currarrow, rotate=\myangletmp, color=#1 ] at (#3-Ipos){};

        % rotate 180 if angle is between 90 and 270
	\pgfmathparse{\myangletmp + ifthenelse(and(\myangletmp>90,\myangletmp<270),180,0)}
	\edef\mylabangletmp{\pgfmathresult}

        \node [color=#1, rotate=\mylabangletmp, #2] at (#3-Ipos) {#4};
    }

What I wanted to achieve originally was to have the same rotation for the voltage/current label as for the bipole-label. See e.g. this:

\begin{document}
	\begin{tikzpicture}
		
		\draw (40:4) to[L+, o-, l=$L_{ab}$, v=v, name=L1, i=i] (40:2) to[V+, -*, v_={\(v_{12}\)}, name=V1, i=\(i\)] (0:0);
		\varr[purple]{V1}{$v_{12}$}
		\varr{L1}{$v_{longName}$}
		\iarr{V1}{$i$}
		\iarr[green]{L1}{$i_{longName}$}
		
	\end{tikzpicture}%
\end{document}

Thus, I need the to decect the label rotation. I tried

\NewDocumentCommand{\iarr}{O{red} D(){below} m m}{% color, where, name, label
    \pgfmathanglebetweenpoints{\pgfpointanchor{#3-Ifrom}{center}}{\pgfpointanchor{#3-Ito}{center}}
        \edef\myangletmp{\pgfmathresult}
        %\typeout{\myangletmp}
        \node [currarrow, rotate=\myangletmp, color=#1 ] at (#3-Ipos){};

        % Name not rotated -> current label not rotated
        \pgfmathparse{notequal(\ctikzgetdirection{#3label},0)}
        \edef\namerottmp{\pgfmathresult}

        % rotate 180 if angle is between 90 and 270
	\pgfmathparse{\namerottmp*(\myangletmp + ifthenelse(and(\myangletmp>90,\myangletmp<270),180,0))}

        \edef\mylabangletmp{\pgfmathresult}

        \node [color=#1, rotate=\mylabangletmp, #2] at (#3-Ipos) {#4};
    }
    \NewDocumentCommand{\varr}{O{blue} D(){below} m m}{% color, where, name, label
        \draw [thin, #1, -Triangle,] (#3-Vfrom) .. controls (#3-Vcont1) and (#3-Vcont2).. (#3-Vto) node [midway, sloped, #2] {#4};
        }
    
    \begin{document}
	    \begin{tikzpicture}
		    
		    \draw (90:4) to[L, o-, l=$L_{ab}$, name=L1] (90:2) to[V, -*, name=V1, i>, l=~] (0:0);
		    \draw (180:4) to[L, o-, l=$L_{ab}$, name=L2] (180:2) to[V, -*, name=V2, v_] (0:0);
    
		    \iarr(above){V1}{$i$}	% current for 1. voltage source
		    \varr(below){V2}{$v$}	% voltage vor 2. voltage source
    
	    \end{tikzpicture}%
    \end{document}

But this places the current label in the curcuit and thats why I used the position of the original label.

[Rmano]

I am quite convinced that I'll try to generate the label info always (even if there is just an i). And the direction info for current arrows too. Do you think that this could fix it?
Finding a syntax to put the labels but not the symbols seems quite awkward now that I think about it...

[judober]

Yes I think having the label info would fix this problem.

[Rmano]

Ok, let's move to #567