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waterlucky
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Join Date: Nov 2007
Posts: 26

Purpose of magnetic coil?

11/27/2007 11:13 PM

I often see a magnetic coil with wires running thru it in a elect. panel; i dun really know what they do.

1) is that for minimising of induced eddy current or magnetic flux?

2) which type of wires should go thru these coil? neutral also?

3) do i need these coil for single phase or 3 phase only? how many should i need?

4) where should i install this coil? after the breakers? or upstream to my equipment?

5) should i use this coil on HT panel? 6.6kv?

thanks to all..
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PWSlack
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
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#1

Re: Purpose of magnetic coil?

11/28/2007 4:43 AM

<1) is that for minimising of induced eddy current or magnetic flux?>

Without a picture, the most likely possibility is that it is a http://en.wikipedia.org/wiki/Current_transformer

<2) which type of wires should go thru these coil? neutral also?>

Just one of the phase conductors. Certainly no more than one per coil, and certainly not the neutral.

<3) do i need these coil for single phase or 3 phase only? how many should i need?>

One for each of the phases for which a current measurement or indication is required. They are fitted to single phase panels as well as three-phase ones.

<4) where should i install this coil? after the breakers? or upstream to my equipment?>

The style of questioning in this post suggests that consulting with an appropriately-experienced panel designer is the first priority. In principle, they are installed upstream of the loads that require current measurement.

<5) should i use this coil on HT panel? 6.6kv? >

The style of questioning in this post suggests that consulting with an appropriately-experienced panel designer is the first priority. HT panel design is not an activity for the inexperienced, on safety grounds.

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Youngin
Active Contributor

Join Date: Nov 2007
Posts: 19
#5
In reply to #1

Re: Purpose of magnetic coil?

11/29/2007 6:24 PM

<2) which type of wires should go thru these coil? neutral also?>

Just one of the phase conductors. Certainly no more than one per coil, and certainly not the neutral.

Just an aside, if there were parallel runs of conductors involved in the selected circuit, wouldn't you route all those of the same phase through the C.T.?
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Epsilon
Active Contributor

Join Date: Oct 2007
Posts: 11
#2

Re: Purpose of magnetic coil?

11/28/2007 7:01 AM

PWSlack has said it all.
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p.k.datta
Active Contributor

Join Date: Oct 2007
Location: Calcutta
Posts: 22
#3

Re: Purpose of magnetic coil?

11/29/2007 11:53 AM

Plesae dont take it as affront, if it was low voltage electronics one can experiment /monkey with ; but to probe in a panel what coils do is to risk life or limb!

invariably voltages involved here would be 440/220 or 120V AC.

please ask a person who is a trained electrician if not an engineer .and of course on site.
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GW
Guru

Join Date: Oct 2006
Location: Surrey BC Canada
Posts: 1571
Good Answers: 42
#4
In reply to #3

Re: Purpose of magnetic coil?

11/29/2007 4:17 PM

Or 600vac in Canada, 690V in some european areas.
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Haajee
Guru

Join Date: Feb 2006
Posts: 1758
Good Answers: 6
#6

Re: Purpose of magnetic coil?

12/03/2007 2:10 PM

"1) is that for minimising of induced eddy current or magnetic flux?"

If all the Phase Cables are passing through one coil & there are 3 such coils then these are CTs [Current Transformers]. You should not be confused with iot as the Conductor passing through it is a SINGLE-Turn [primary] & the coil is the secondary of TRANSFORMER.
The Secondary [2 wires or Lugs on CT]is connected to Panel-Current meter.

Some-times 2 or more turns may be found where the user cannot find a suitable CT matches the technical requirements by adding some turns in the primary.

By 2 turns the FSD voltage is doubled & Meter reading scale is considered to be half of the Graduated Scale of meter.
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Epsilon (1); GW (1); Haajee (1); p.k.datta (1); PWSlack (1); Youngin (1)

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