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Participant

Join Date: Sep 2014
Posts: 3

Electrical Panel Wires Burnt Out

02/12/2021 1:16 AM

Hi

I Had a problem with my 11KV MV DG panel one of the feeders which are feeding on 11kV Dg. The Problem is current transformer secondary wires its 4sqmm which are connecting to relays & Meters is burning out. this is the 3rd time its happening what could be the reason for the cause.

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Power-User

Join Date: Jan 2010
Location: Hyderabad
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#1

Re: Electrical panel wires burnt out

02/12/2021 1:28 AM

It could be loose connection in the wiring that causes sparking initially and ending up as fire burning the wiring.

It could be the voltage across CT secondary terminals is exceeding the wiring specifications and the voltage is persisting for sometime to cause insulation failure / burning. Check the CT parameters and estimate the max voltage at the CT secondary terminals when there is fault in the feeder and high current flows through CT secondary. Verify the wiring specifications with the calculated voltage. Also, check the duration how long this voltage (fault in the feeder) is lasting.

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Raghunath
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#3
In reply to #1

Re: Electrical panel wires burnt out

02/12/2021 6:36 AM

GA.

If a current transformer secondary circuit is opened partly or completely while the primary circuit is carrying current, there exists the possibility of a super-high voltage being generated across the opening contacts or connections. It won't take long for a fair amount of heat to be dissipated and cause the melting or burning of conductors and their insulation.

BS7671 requires no fuses/breakers/whatever in the secondary circuit for this reason. After all, the only way an overcurrent could appear in the secondary is for an overcurrent in the primary to cause it, and the primary must be protected against that happening.

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#6
In reply to #3

Re: Electrical panel wires burnt out

02/12/2021 9:07 AM

I have used Oxguard for many years,even on battery terminals.Works great,even in very hostile environments.

Non-contact temperature measurement has evolved tremendously since the '70's when an IR camera required an Argon purge cylinder,weighed about 15 pounds,and cost around $30,000.

I remember taking pictures with a modified Instamatic camera to show problems to customers.

It was like X _ray vision,showing hot connections without opening the panels.

Modern tech has made it much cheaper and simpler and saved millions of $ in repairs.

Every company should have one now.

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#2

Re: Electrical panel wires burnt out

02/12/2021 1:29 AM

You've got a bad connection somewhere it seems....I use an infrared detector for locating hotspots in electrical systems...You need to clean and connect the wiring, maybe use some cu/al or conductive grease on the connections, then energize the circuit under load and check the amp draw of each line, then the temperature of each connection point...

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#4

Re: Electrical Panel Wires Burnt Out

02/12/2021 6:51 AM

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#5
In reply to #4

Re: Electrical Panel Wires Burnt Out

02/12/2021 8:46 AM

One video worth a Million words.GA!

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