Voltage conventions

Feb 03, 2010 4 Replies

Hello to everybody, I have a doubt about the convention I use to indicate a voltage in a circuit. I use to put an arrow between the nodes in which I want to measure the voltage. The arrow head indicates where I imagine to put the positive cable of my voltmeter. This is how I learned years ago, when I was a student in Italy and France and I have done this way for many years now. I have a colleague of mine who has pointed to me that the IEEE convention states the opposite and the arrow head indicates instead the negative cable of my imaginary voltmeter. I knew that the two conventions exist depending on the geographical area, but I was wandering which particular IEEE standard states this and if this is effectively used for example in north America.



Thanks a lot!


Real engineers ignore the IEEE.

John

I write a floating plus and minus around the voltage label. Voltage doesn't flow, therefore it should not be written with arrows.

Current arrows most often point down or to the right. I have seen a few professors who make up arrows for voltage across a component, directly across from current arrows pointing down. How horrible.

Tim

-- Deep Friar: a very philosophical monk. Website:

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My own practice is to write the voltage close to the point where the measurement is taken, with a + or - minus sign as appropriate, without an arrow. In cases where it's not convenient to place the voltage label close to the point, I point to it with an arrow, but in such a way that the arrow is perpendicular or diagonal to any nearby conductor and cannot be mistaken for an indication of current flow. Such voltage markings are intended to be understood as taken with respect to ground.

When I want to indicate the voltage drop across an ungrounded component, I point to each end of the component with an arrow and write the voltage in between the arrows.

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