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Ground clip

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Ground clip

Postby R_v_x » Wed Feb 07, 2018 9:46 pm

Have another question regarding my circuit I work with.
So I´m suppose to measure the drop voltage by connecting 3 electronic items to a main output.
Each item will be connected at the same time as a transformer in order to reduce the voltage from 230 to 12 Vs.

After that I will connect a probe to the transformer, and the other end of the probe (A BNC-koax) goes into channel A at the Picoscope.
And finally Picoscope ----> PC.
But I can´t figure out where to connect the ground clip attached to the probe?
My teacher described it as something very important to remember (which it is obv), so I figure it´s better to be safe than sorry, and therefore I´m asking you.
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Joined: Tue Feb 06, 2018 9:09 pm

Re: Ground clip

Postby Gerry » Wed Feb 14, 2018 10:33 am

Hi R_v_x,

OK, just in the interest of preventing you from getting any unsafe advice, first of all, I would hope that your school/college has you working with suitably safe apparatus, in terms of potential hazards (i.e. that the transformer connections, the ones you will make, and the circuitry around it follow the recommendation of whatever Standards have been specified for Electrical safety in School/College classrooms/labs in your region). Essentially, there should be safe handling of a transformer failure (e.g. quick acting current interuption for insulation breakdown, overloading, etc) and there should also be a low resistance path from the probes ground clip back to the buildings electrical earth. It shouldn't be necessary, but you should check anyway that this is the case, because you need to be 100% confident that the apparatus is safe, before following any comments on this forum.

I'm assuming that the transformer primary is connected to the mains (hopefully through a fused live connection), that the electronic components (items) will be connected to the secondary, and that the probe will be measuring the voltage across the connected electronic component. So, the answer to your question really depends upon what type of transformer you have, and what else you have connected in the secondary circuit. But in order to be able to answer your question correctly and completely, we need confirmation of exactly how everything will be connected up.

So, could you give us a diagram of the connections from the mains power supply (including ground/earth) to the transformer (including any centre tap, and/or core connection), then to any components on the secondary winding side of the transformer (including any bridges etc,) and including where you intend to connect your electronic 'items'. Could you also tell us if you will be using a computer that has a connection to mains ground/earth.


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