Comments on: what is vacuum drying process/method of industrial drying oven of transformer https://nachengg.net/vacuum-drying-process-method-of-industrial-drying-oven-of-transformer/ Oil filtration machine, VPI plants, industrial ovens Wed, 04 Jan 2017 00:15:21 +0000 hourly 1 https://wordpress.org/?v=6.8.1 By: nach https://nachengg.net/vacuum-drying-process-method-of-industrial-drying-oven-of-transformer/#comment-52 Wed, 04 Jan 2017 00:15:21 +0000 http://nachengg.net/?p=982#comment-52 In reply to B. Rama chandra murthy.

Thank you Mr. Murthy, for your query.
In a destructive type of testing, you may need to
(a) take a section of the impregnated winding, and observe the penetration of the resin/varnish/epoxy.
(b) In case the penetration of the resin/varnish is not satisfactory, rework on the VPI cycle parameters like soaking time, pressure time and pressure level. Redefine the VPI cycle and then recheck as per (a) above.

In non-destructive testing, you may need to
(a) Take IR and Dielectric test to confirm the VPI cycle accuracy
(b) Assess the viscosity of the resin/varnish for better results

]]> By: dinesh https://nachengg.net/vacuum-drying-process-method-of-industrial-drying-oven-of-transformer/#comment-43 Sat, 09 Jan 2016 22:25:42 +0000 http://nachengg.net/?p=982#comment-43 this is really awesome blog thanks for that..

]]> By: B. Rama chandra murthy https://nachengg.net/vacuum-drying-process-method-of-industrial-drying-oven-of-transformer/#comment-41 Wed, 09 Sep 2015 17:21:30 +0000 http://nachengg.net/?p=982#comment-41 Dear Sir,
How to evaluate the VPI ( Vacuum pressure impregnation ) process. Is there any test methods, ( Meager and HV )
and distract and non dist-active test required or not, Please explain.

Best Regards,
B R C Murthy.
Sr.Engineer PE.
MEDHA Servo drives pvt.ltd.

]]> By: nach https://nachengg.net/vacuum-drying-process-method-of-industrial-drying-oven-of-transformer/#comment-39 Fri, 04 Sep 2015 04:25:03 +0000 http://nachengg.net/?p=982#comment-39 In reply to Ahmed Abourehab.

Hello Ahmed!
I am answering to your queries point wise.
– what is the recommended drying process for transformer 40 MVA
Drying process involves two techniques (a) Conventional Vacuum Drying (b) Vapour Phase Drying
I shall recommend conventional vacuum Drying for transformers upto 40MVA, from the view point of (i) investment cost on Vapour phase drying, (ii) Energy consumption (iii) Cycle time (iv) results obtained (Ex. Polarisation Index)

– what is the accepted amount of tan Delta or dielectric power factor for different power rates of transformers.
You may need to refer the appropriate standards in your country

– I need complete chart Temp- time and pressure -time diagram for drying process
This is very much application specific, and varying from transformer to transformer.
your prompt reply will be appreciated

You may revert back to me on nikhil@nachengg.net

]]> By: Ahmed Abourehab https://nachengg.net/vacuum-drying-process-method-of-industrial-drying-oven-of-transformer/#comment-38 Tue, 01 Sep 2015 23:54:46 +0000 http://nachengg.net/?p=982#comment-38 very good assay about drying of transformers, but I need to Know,
– what is the recommended drying process for transformer 40 MVA
– what is the accepted amount of tan Delta or dielectric power factor for different power rates of transformers.
– I need complete chart Temp- time and pressure -time diagram for drying process
your prompt reply will be appreciated
Ahmed

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