Transformer with capacitive load.

Thread Starter

Gibson486

Joined Jul 20, 2012
327
I have an AC transformer. The load is purely capacitive....Do I want to ground the secondary side if I want consistent voltage across the capacitive load?
 

Thread Starter

Gibson486

Joined Jul 20, 2012
327
Well, maybe I think I understand this right....

When I measure the output (positive side of cap), it shows some voltage. However, when I ground the probe to the negative side, the voltage goes up. At first, I thought it was because there was a path to ground.

I am guessing what is happening is that since the probe is high impedance, I am, in essence, creating a large valued resistor in parallel with the cap. This, as a result, increases current at the load, which also increases current at the primary side. Because more current flows, the voltage goes up on the secondary. Is that feasible?
 

kubeek

Joined Sep 20, 2005
5,733
No, not really.
Where do you have the ground lead when you are measuring the presumably ungrounded secondary? Also how can you have a positive and negative side of cap if the only thing connected to the secondary is the cap? Better post a schematic of what you are actually doing.
 

bertus

Joined Apr 5, 2008
20,870
Hello,

As the transformer will isolate from the input, the ground on the output will not matter.
Only the phase will change dependend on where the groud is.



(I reposted your picture in a format that can be read in any browser).

Bertus
 

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kubeek

Joined Sep 20, 2005
5,733
Still no idea what instrument you are using, and what changes in the schematic and gives you higher voltage. Could you be a little bit more detailed about what you are doing and how?
 

JayArr

Joined Mar 11, 2013
14
When I measure the output (positive side of cap), it shows some voltage. However, when I ground the probe to the negative side, the voltage goes up.
When you measure the output the first time, with "some voltage" where is the ground lead of the scope attached?

You know you can't read a voltage with only the positive probe and the ground not connected right?

Voltage is measures "across" something so you need two reference points.
 
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