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Suranta Ginting
Participant

Join Date: Apr 2008
Posts: 2

Tap changer burned by Electric spark

04/10/2008 10:31 PM

I have Distribution transformer 6.6KV/0.4 KV, 3 ph,50 Hz, Z=7%, 2000 KVA

With off load Tap changer

Firstly I checked at SWG the voltage unbalance between phase and then test turn ratio also not good then we open the Tank cover and check the Tap changer was burned by electric spark.

Anybody can advise me what is the root cause tap changer burn

Thanks and regards

S Ginting
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V.I.Abraham
Guru
Safety - ESD - New Member India - Member - New Member Engineering Fields - Energy Engineering - New Member

Join Date: May 2007
Location: Pune , India
Posts: 875
Good Answers: 42
#1

Re: Tap changer burned by Electric spark

04/11/2008 12:25 PM

Most probably it is because of loose contact in the tap changing switch which was not noticed timely. Finlay the spark resulted in the burning of the tap changer.
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Suranta Ginting
Participant

Join Date: Apr 2008
Posts: 2
#3
In reply to #1

Re: Tap changer burned by Electric spark

04/11/2008 9:20 PM

Mr.Abraham

Thank you for your response

We operate tap changer on SWG switch off position / no load condition also we grounded the system

Anyway we are now waiting Technical clarification from our Vendor what is the root cause

FYI , already two times tap changer burned with different transformer but same type/capacity 2000 KVA

Best regards

SG
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biswanath.das
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Join Date: Oct 2006
Location: Kolkata, India
Posts: 447
#6
In reply to #3

Re: Tap changer burned by Electric spark

04/23/2008 6:23 AM

Check if there is persisting resistance fault in the circuit.

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North of 60
Guru
Canada - Member - If there is a way to screw someting up, there is someone to do so! Safety - Hazmat - New Member

Join Date: Mar 2007
Location: Iqaluit, NU. Canada
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Good Answers: 140
#2

Re: Tap changer burned by Electric spark

04/11/2008 5:12 PM

Or... the "Off Load" tap changer was operated while energized and under load. A stupid thing to do, but a common one unfortunately.

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V.I.Abraham
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Safety - ESD - New Member India - Member - New Member Engineering Fields - Energy Engineering - New Member

Join Date: May 2007
Location: Pune , India
Posts: 875
Good Answers: 42
#5
In reply to #2

Re: Tap changer burned by Electric spark

04/14/2008 5:29 AM

Hi " North of 60 ",

You are correct that if by mistake some body operate tap changer on load it will result in burning and heavy spark and cause fatal burning and may cause fire . But normally experienced people who operate substations are very safety cautious and rarely do that mistake. Even without that also it is observed that tap change switches burn.I have investigated some such cases and it was noticed that the spring and ratchet assembly of the tap changing switch get misaligned and after repeated operations sparking starts due to loose contact and when left out un noticed result in burning.This is the reason I used to instruct my staff to check the tap changing switch periodically during preventive maintenance.
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nesubra
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Join Date: Nov 2006
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#4

Re: Tap changer burned by Electric spark

04/12/2008 4:28 AM

I agree with North of 60

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biswanath.das (1); nesubra (1); North of 60 (1); Suranta Ginting (1); V.I.Abraham (2)

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