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Atanasio
Participant

Join Date: May 2010
Posts: 2

Capacitance measurement during vpi impregnation

05/21/2010 1:00 PM

I am developping a data capture system to measure capacitance during VPI cycle that graphs underpressure (vacuum), pressure, temperature and capacitance for HV stator (mica+poliester or mica+glass) along the impregnation.

With this system I see how capacitance increases untill it stabilizes, so i know that resin has fullfill all insulation tapes and i can get out the stator from vessel to curing oven.

Do you know how this graphs should be??

Its normal that when the resin flooding starts, capacitance decreases and then capacitance increases??

*Sorry if you dont understand my english
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Pathfinder Tags: HV Impregnation VPI
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RHABE
Guru

Join Date: Dec 2006
Location: Germany 49° 26' N, 7° 46' O
Posts: 1950
Good Answers: 109
#1

Re: Capacitance measurement during vpi impregnation

05/22/2010 5:18 PM

Hi,

do you want to measure penetration

or do you want to measure the curing of the resin?

How do you measure the capacitance?

We have done this to measure impregnation quality but did not try with copper wires and resin. Carbon-fibres are conductive too but much less conductivity.

RHABE
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Atanasio
Participant

Join Date: May 2010
Posts: 2
#2

Re: Capacitance measurement during vpi impregnation

05/23/2010 4:12 AM

I measure capacitance during impregnation, when resin penetrates the insulation tapes.

I measure with a LCR bridge (Hameg HM8118) that every minute takes the capacitance value and sends to one computer.
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RHABE
Guru

Join Date: Dec 2006
Location: Germany 49° 26' N, 7° 46' O
Posts: 1950
Good Answers: 109
#3
In reply to #2

Re: Capacitance measurement during vpi impregnation

05/25/2010 2:21 AM

Hi,

how do you take the measurement: coil to housing?

Bridge configuration or charging-decharging measurement or other?

how big is the typical capacitance and the resolution you need?

I had often only 10pF total C and needed 1fF resolution.

If you want to measure your resin then (I think) it will be good to take the stray capacitance of the coil and compare this to a similar wound coil that is not undergoing impregnation.

RHABE
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