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[ASK] why groundig can drop the voltage to earth?

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Aziz Efendi

Fri Dec 30 2011, 02:34AM

Registered Member #4022 Joined: Fri Jul 22 2011, 04:36AM
Location: Indonesia
Posts: 9

Why is grounding to the earth at a DC high voltage circuit that I made using a flyback transformer voltage to be down, I initially measured the voltage of the without grounding to the earth a measurable voltage results in approximately 62 KV gauge while when I measured using a grounding to the earth after its voltage drops to 47 KV, what influence it so that the voltage to drop when I use the grounding to the earth?

I beg enlightenment to all experts of high voltage in this forum
thank you

Antonio

Fri Dec 30 2011, 02:42AM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

How, exactly, is the circuit? How did you measure these voltages? They seem too high.

Alex M

Fri Dec 30 2011, 02:53AM

Registered Member #3943 Joined: Sun Jun 12 2011, 05:24PM
Location: The Shire, UK
Posts: 552

I am guessing you are using some sort of high voltage probe to measure this?

It might be that the earth pin on the flyback floats below earth but when you earth it the voltage between the HT lead and earth pin is much less.

Aziz Efendi

Fri Dec 30 2011, 03:02AM

Registered Member #4022 Joined: Fri Jul 22 2011, 04:36AM
Location: Indonesia
Posts: 9

Alex1M6 wrote ...

I am guessing you are using some sort of high voltage probe to measure this?

It might be that the earth pin on the flyback floats below earth but when you earth it the voltage between the HT lead and earth pin is much less.

Yes, that's right
I use the probe for measuring high voltage, if the resistor is used as the probe can affect the measurement of high voltage?, what do you mean, it's floating?, I do not understand ...

I measured using a probe from the flyback transformer which I combine, each have about 30 kV output voltage, and then I combine into 60 kV, the voltage should read approximately 60 KV, but when I was grounding to the earth the result to be changed about 47 KV
I get confused ...

Aziz Efendi

Fri Dec 30 2011, 03:05AM

Registered Member #4022 Joined: Fri Jul 22 2011, 04:36AM
Location: Indonesia
Posts: 9

Antonio wrote ...

How, exactly, is the circuit? How did you measure these voltages? They seem too high.

I measured using a probe from the flyback transformer which I combine, each have about 30 kV output voltage, and then I combine into 60 kV, the voltage should read approximately 60 KV, but when I was grounding to the earth the result to be changed about 47 KV
I get confused ...

Antonio

Fri Dec 30 2011, 01:15PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

Imagining how two flyback transformers could be connected for more voltage, in series, since you didn't describe the circuit, it's evident that it's difficult to keep enough insulation between the primary coils and cores, and the HV windings. Maybe impossible. It may be happening that when you make the measurement without ground the insulation is high enough, with one transformer producing positive voltage and the other producing negative voltage, with the point where they are joined at low voltage. Note that this measurement with a single HV probe can easily damage your instrument. When you ground one end the other end jumps to twice the voltage, and the union point to the full output voltage of the grounded transformer. Leakage at the union may be the cause of the observed drop.

Aziz Efendi

Sat Dec 31 2011, 09:11AM

Registered Member #4022 Joined: Fri Jul 22 2011, 04:36AM
Location: Indonesia
Posts: 9

Antonio wrote ...

Imagining how two flyback transformers could be connected for more voltage, in series, since you didn't describe the circuit, it's evident that it's difficult to keep enough insulation between the primary coils and cores, and the HV windings. Maybe impossible. It may be happening that when you make the measurement without ground the insulation is high enough, with one transformer producing positive voltage and the other producing negative voltage, with the point where they are joined at low voltage. Note that this measurement with a single HV probe can easily damage your instrument. When you ground one end the other end jumps to twice the voltage, and the union point to the full output voltage of the grounded transformer. Leakage at the union may be the cause of the observed drop.

Have not been there who have the series on the flyback transformer?, Whether by having my series on the flyback transformer is considered to violate the rules?, Then how do I have to build a high voltage generator that can exceed 30 KV?, Thank you for your advice , but I also need help from you ...

Patrick

Sat Dec 31 2011, 02:48PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

I am thinking that your dividing the E-field unevenly, perhaps through static coupling to the table surface your voltmeter is laying on. grounding would make a diference in that case.

radiotech

Sun Jan 01 2012, 05:19AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

Please make a diagram of what you are doing, and show the voltages and the probe.

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