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Re: Switchgear problems [Re: Tesla] #212788 02/13/14 02:16 PM
Joined: Jul 2001
Posts: 599
J
JBD Offline
Member
Originally Posted by Tesla
I've never seen any cut sheet that explained the physics of E & B fields.
I was not asking for this nor would I expect it.

Quote
“Failure to install CT's in the correct orientation and on the correct phase will lead to inaccurate meter readings...”


A warning about incorrect readings would not normally mean be construed to be a warning about equipment failure due to overheating.

I asked for installation instructions from any CT manufacturer that provided a warning that CTs should not be mounted 'near' a 90² turn in the conductor.

Your reply was that this is a topic that is evidently only presented in the deepest E & B field theory discussions.

Quote
The CT's that lack shielding are plainly dimensioned for plain vanilla bus bars – rising vertically – in CT sections.


Your lack of field experience (outside the world of utilities or academia) is very evident. The CTs I used as an example are intended to be mounted around the cables in the wiring gutter of panelboards.

Last edited by JBD; 02/13/14 02:16 PM.
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Re: Switchgear problems [Re: JBD] #212789 02/13/14 06:33 PM
Joined: Jun 2004
Posts: 1,273
T
Tesla Offline
Member
The unshielded CTs in the pdf you cited are as I described.

The CTs suitable for use around cables are as I described.

Again, from the pdf you cited.

B fields induce E fields when they are changing.

The photo shows a badly behaving CT attempt that goes largely against the assurances you're providing.

Telling us it can't be happening is not helpful.

Lacking any further postings from the OP, I can't be sure of much... other than this is a fouled up install.

The goo on the floor certainly looks like it was melted down from the rigged up CT.

Please opine as to what you think is the cause.


Tesla
Re: Switchgear problems [Re: Wmackay] #212790 02/13/14 07:39 PM
Joined: Apr 2002
Posts: 7,150
HotLine1 Offline
Member
I still think the mess is from a sloppy install. I doubt enough heat could build from the neutral buss or what appears to be a fabricated CT.

There appears to be some scorching on the phase buss alhgso.

Looks like the OP is a 'hit n' run' guy.



John
Re: Switchgear problems [Re: Tesla] #212791 02/13/14 09:17 PM
Joined: Jul 2001
Posts: 599
J
JBD Offline
Member
Originally Posted by Tesla
Telling us it can't be happening is not helpful....

Please opine as to what you think is the cause.


I have not said something is not happening.

I said it is common industry practice to have CTs near 90² bends in conductors. I also said that many if not most CTs are not shielded. The predominant number of CTs are not installed in 'vertically oriented CT cabinets'.

I have simply asked you to provide any published instructions that would have warned an installer not to put this CT where it is due to possible overheating.

In my first post, I said this CT should immediately be removed from service.



I did find one set of warnings for mounting of zero sequence rectangular CT, but it relates to nusiance tripping of GF relays.

Page 13
http://www.electricalmanuals.net/files/RELAYS/I-GARD/MGFR/C-700.pdf

Re: Switchgear problems [Re: Wmackay] #212980 03/04/14 08:52 PM
Joined: Apr 2002
Posts: 7,150
HotLine1 Offline
Member
Bump
What happened to the OP??



John
Re: Switchgear problems [Re: Wmackay] #212982 03/04/14 09:46 PM
Joined: Dec 2000
Posts: 4,282
electure Offline
Member

His last visit here was the day he made the post.

Re: Switchgear problems [Re: Wmackay] #212984 03/04/14 10:29 PM
Joined: Apr 2002
Posts: 7,150
HotLine1 Offline
Member
Sure would be nice to have some additional info!


John
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