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Anonymous Poster #1

Voltage Transformer Dummy Load

01/10/2012 6:02 AM

Sir,

In lv switchgear we are using 3phase 440/110v 200va vt, since it is using only metering, customer need to provide 40watt dummy load. so we used 40watt resistor in the circuit. but when 3nos. resistor is using heat is generating inside the vt compartment, let me know is there any other load to connect instead of resistor which not producing heat, or is there any special type of resistor which doesnt emit heat, we need 40watt. thank you,
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SolarEagle
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Join Date: Mar 2007
Location: by the beach in Florida
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Good Answers: 1817
#1

Re: voltage transformer dummy load

01/10/2012 6:37 AM

Light up the panel with LED's...

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pravinba@yahoo.com
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Join Date: Dec 2010
Location: visakhapatnam, India
Posts: 11
Good Answers: 2
#2

Re: voltage transformer dummy load

01/10/2012 6:46 AM

Can you please tell us " what is the requirement of 3 nos 40 W resistors in the VT compartment" ? what it does?
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pravinba@yahoo.com
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Location: visakhapatnam, India
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#3

Re: voltage transformer dummy load

01/10/2012 6:49 AM

can you please tell us "what is the requirement of 3 nos 40 W resistors in the VT compartment "? what does the customer requires?
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Anonymous Poster #1
#4
In reply to #3

Re: voltage transformer dummy load

01/10/2012 7:15 AM

there is one specification for the job that vt should be with minimum va of 200va, next one, if the connected burden is less than 25% of the rated va rating loading resistors to be provided to maintain the specified accuracy.
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electricalexpert65
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Join Date: Oct 2009
Posts: 2061
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#5
In reply to #4

Re: voltage transformer dummy load

01/10/2012 7:49 AM

You could have bought a chappal to suit your legs rather than cutting or packing your legs to suit the chappal you have bought wrongly. The CT or VT rated burden should be as close to but not less than the total burden connected to the CT or VT, including the CT or VT's secondary winding impedance, the lead burden & the load burden. If the loads connected to your VT are only metering, then why did you choose a 200VA VT in the first place? You are uneconomical as well as the size of the VT would be large, occupying a larger panel space. Add to this the accuracy problem, when you connect an actual burden of less than 25% of the rated burden. And also you are wasting precious energy.

I would strongly advise you to replace your VTs with properly rated VTs.
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Anonymous Poster #1
#6
In reply to #5

Re: voltage transformer dummy load

01/10/2012 8:12 AM

sir,

I know this, but consultant and customer is our boss, we cant argue with them they r not thinking practically, follows only wht is written in specification. they need wt is in spec. boss is always boss. the selection of vt is correct. we cant deviate the spec. even though actual consumption is 5va, they need 200va. this is to be followed in new panels also. that is oil company spec for gulf. now i need the solution for heat prblm. can u pls. recommend any soln. for my prblm.
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electricalexpert65
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#9
In reply to #6

Re: voltage transformer dummy load

01/11/2012 7:14 AM

If "boss is always boss" and if such a boss asks you test the availability of electric power in a distribution panel bus with your bare fingers, will you still oblige and follow your dictum of "boss is a boss" & choose not to argue with your boss?. We cannot advocate incorrect selection even if it is by your "so-called' bosses. If your consultant is adamant on specifying a 200VA VT for a load of just 5VA, he is no more a consultant; I would call him an "INSULTANT", for he is an insult to the profession. Now, you need to change both the VT and your consultant as well!
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Yahlasit
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Join Date: Dec 2008
Location: Cd. Juarez, Chihuahua, Mexico.
Posts: 1023
Good Answers: 69
#7

Re: Voltage Transformer Dummy Load

01/10/2012 8:43 AM

You can use this Ohmite's series of power resistors, or WFH or series 89 wich used to be military standard.

If there is no restriction as per the location, mount it in the ouside of the cabinet (back and/or top), providing proper safety guards with enough air flow or spacing for convection.

Regards

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zaheer khan
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Join Date: Jan 2012
Posts: 6
#8

Re: Voltage Transformer Dummy Load

01/10/2012 2:11 PM

I agree with the answer given by electricalexpert66.
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Anonymous Poster (2); electricalexpert65 (2); pravinba@yahoo.com (2); SolarEagle (1); Yahlasit (1); zaheer khan (1)

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