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Power-User

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Tap Changer Location

01/27/2017 11:52 AM

"They" use to say in text books that tap changers are placed on high voltage side of transformer because current is low and easy to break. I think this explanation is wrong. Tap opening creates arc and it is voltage creating the arc and not current flow. i think tap changers are placed on H.V side just because HV side is the outermost winding and it is mechanically accessible for tap changing. What do you guys think?

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#1

Re: Tap Changer Location

01/27/2017 12:51 PM

Haris, why don't you get the text books re-written to align with your opinion.

I'm sure the scholars who wrote them would gladly change them for you, given the outstanding displays of knowledge you demonstrate here every day!

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#2

Re: Tap Changer Location

01/27/2017 1:10 PM

Maybe for both reasons:

"Why tap changer is placed on high voltage side?

The tap changer is placed on high voltage side because:

1) The HV winding generally wound over LV winding hence it is easier to access the HV winding turns instead of LV winding.

2) Because of high voltage the current through the HV winding is less compared to LV windings, hence there is less “wear” on the tap changer contacts. Due this low current, in on load tap changer the change over spark will be less."

https://en.wikipedia.org/wiki/Tap_changer#cite_note-3

http://ecetutorials.com/transformer/transformer-tap-changer/

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#3

Re: Tap Changer Location

01/27/2017 2:16 PM

“What do you guys think?”

If I said what I thought I would be banned by the moderators.

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#5
In reply to #3

Re: Tap Changer Location

01/27/2017 3:57 PM

Haris is a total loss.

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#4

Re: Tap Changer Location

01/27/2017 2:35 PM

One aspect is that the HV side has more turns, making it easier to provide incremental steps.

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#6

Re: Tap Changer Location

01/27/2017 7:57 PM

Actually there is no arc on the tap changer contacts.

The tap changer preselects the required tap while the original tap is still carrying the load, so those contacts close under "no load" conditions.

The diverter switch then makes the break, and it's those contacts which experience the arc, and that arc is limited by the diverter transition resistors.

The tap changer then opens the original tap contacts under "no load" conditions, so no arcing will occur at those opening contacts.

All of the load making and breaking is done by the diverter switch.

As has been noted by others, the HV side is carrying less current, and that prolongs the life of the diverter contacts, the fact that the HV coil is on the outside has little influence on the decision as once the leads have been brought out from either the inner or outer windings, there is no need to access them again under normal operating conditions.

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Guru

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#7

Re: Tap Changer Location

01/28/2017 6:07 AM

Some tap changers are called plumbers. Some are called handyman. Have you thought to ask the local plumber/handyman. Tap openings create flow and some flow may create an arc. This is attributed to fracked water supplied in flow line from the generating station, (pump yard or water storage capacitor).

But knowing transformer manufacturers they placed these taps on the side just to p**ss people off when they need to work on them. Transformer manufactures and designers just love to have a good laugh. See the plumber, he will know better.

N.B. my friend had a tap on the shoulder last week. He had it changed to a tap on the head by a tap changer in a car. He had given him a tap on the side.

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#8

Re: Tap Changer Location

01/28/2017 7:44 AM

I disagree with your ideas.

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#9

Re: Tap Changer Location

01/30/2017 4:56 AM

OK: "There doesn't seep to be any overlap between best practice and the stated opinion."

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#10
In reply to #9

Re: Tap Changer Location

01/30/2017 5:42 AM

<...seep...> seem

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#11

Re: Tap Changer Location

01/30/2017 3:26 PM

There are a number of reasons but in the end the big one is it is cheaper for transformer manufacturers to use tap changes on the lower current side.

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