[kolias]

I was looking for a 36 VDC digital meter on ebay but noticed a lot offer a dual display volts / amp meters and some also include a shunt (don’t know what this is for)

Never connected an Amp meter and wonder how it is done

I would like to measure the volts / amps for my 4 axis drivers; the power supply is 36 VDC / 9.7A and the drivers are each 3A

[xjdubber]

The shunt is usually used with ac can be dc as well but the wire is wound around it, if its dual volt and amp display it will be wired in series.

[kolias]

So how do I wire the amp meter?

[Al_The_Man]

A Shunt is traditionally used with DC current, it is essentially a very low resistance <1ohm, inserted in the conductor to be measured at some point and the volt drop across it is relative to the current.
The efficient simple way with AC is a current transformer, this resembles a small toroid where the conductor to be measured is simply looped through the C.T. once or twice depending on what ratio is needed.
If it is DC you are measuring then the shunt method would work, inserted in series with the conductor.
Al.

[xjdubber]

Yes Al is right shunt is for measuring DC not AC, its a CT (current transformer) that can be used to measure dc. To wire it in connect one side to your Supply + and the other side to the load, this would be series.

[kolias]

Thank you both but I'm not really clear on how to connect the Ampmeter. Perhaps it's simple for someone knowledgeable but I'm not

Each driver has 2 connections for the POS / GND from the power supply unit plus 4 connections for the motor (A+, A-, B+, B-). It also has 6 connections for the controller. Which connection do I use for the shunt?

On ebey they say if for less than 10A, no shunt is required. In my case I have 4 stepper drivers each at 3A. So do I connect the shunt to all 4 drivers or just one?

Is there a typical wiring for such a connection?

[Al_The_Man]

Realistically trying to monitor the current on servo's or steppers is not really a satisfactory practice due to the constantly varying drive signal, if anything I would just put it in the power supply side from P.S. to drives.
Al.

[xjdubber]

You have to decide what you want to do, monitor the current on each stepper individually or all together, you cannot connect the amp meter directly between the motor and the drive, it will have to connected in series on the power supply for the drive. Why are you wanting to do this anyway?

[kolias]

Sound good Al but again how do I connect the Ampmeter?

On ebay there is a wiring schematic but in Chinese and although I can guess how to connect I would rather not guess. On the back there are 3 wires; the Black / Red I will assume is for the Voltmeter and the Yellow is for the Ampmeter. So if I want to measure the Amps drawn from the power supply unit do I connect the Yellow to the positive of the power supply unit along with the Red for the Voltmeter?

Since they say that for anything less than 10A the shunt is not required, do I need the shunt?

Why I need the Ampmeter? I thought it is a good idea to know the Amps drawn in case of troubleshooting. In addition, most of the meters sold on ebay they are volt / amp meters so might as well use both

[Art Mann]

I will be honest with you. The type of questions you are asking lead me to believe you don't need to be altering the wiring from your power supply. Someone already told you that the yellow wire needs to be "in series" with the power supply output. That is a true statement. If you don't know what that means, then you may not know enough to keep from burning up your equipment.

[ViperTX]

It might help to have a data sheet for this device.

However, it seems based on what you mentioned about < 10 amps that there is an inline shunt.

So, I believe you would wire it like this: Neg side of Ampmeter goes to Neg. Side of Supply.

You would remove the Pos. Connection of the power supply from the load and connect the positive side of the power supply to the Yellow Lead. Then you would wire the Red (Positive Lead of the Ampmeter) to the load (where the positive side of the power supply was previously connected).

I would try this out on a bench set up. Where the load is some "load resistor" I would pick a load resistor that draws less then 2 amps from the power supply. Use ohm law R = V/I and the resistor must be in watts P=IV. V is the voltage of your DC supply, I is 2 amps and the rest is based on solving the formulas above.

Paul

[kolias]

Thank you Paul for the answer, it was exactly what I'm looking for and I don’t know why it took 11 posts on this thread to get the answer to my question. I don’t have a data sheet yet because I have not purchase the meter. Looking to find one that is simple and does not require 2 power supplies

Hey Art Mann, I though forums exist to help people learn and this wonderful forum has helped me to learn a lot. If we don’t ask stupid questions we will never learn and I would rather ask then burn something. As I mentioned on my first post, I never connected an Amp meter and although it is not a rocket science when I work with electrical stuff which I don’t understand I ask LOTS of questions and so far I never burned anything. Regarding the yellow wire, I understood that part but there are more wires involved to connect the Ampmeter and Paul hit it right on.

[xjdubber]

Kolias,

It took 11 posts for you to figure this out because you do not understand what the word series means. You probably should maybe google "what is a series electrical circuit" and read up a little so you actually understand what you are doing.