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Feeder riser clamp

Feeder riser clamp

Feeder riser clamp

(OP)
Is anyone aware of any non magnetice or non metallic feeder rised clamp to avoid any magnetic coupling and circulating current in the clamp itself?

If you do I will appreciate a quick response.

Thanks a lot in advance.

 

RE: Feeder riser clamp

I am not sure what this "feeder riser clamp" might be.  Are you talking about cable supports in a long vertical riser?  Or something else?  If it's the first, than I would suggest Kellums cord grips-there are many varieties.  If you mean something else, more info is needed.

RE: Feeder riser clamp

(OP)
To be more specific I need to clamp aluminum pipe about 3-4" containing two 15kV 2000kcmil shielded cables to the the riser pole. The concern is the circulating current in the clamp due to magnetic coupling.
 

RE: Feeder riser clamp

(OP)
I appreciate all your comments, but I need a clamp which can support a vertical run attaching conduit to the pole.

Bill,

It appears that the one you sent is for horizontal run and attaches to the unistrut

 

RE: Feeder riser clamp

Mount the unistrut horizontally with the opening facing forward. Run the conduit vertically. Install the clamp. These clamps are used in any position.
Also check out the P2054.
http://www.unistrut.com/Browse/cat_detail.php?S=S06&P=P2024
I understand that these are available in stainless.  

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Feeder riser clamp

(OP)
I am not sure how this would get rid of the circulating current?

RE: Feeder riser clamp

yes they are abailable, I was in a substation which used some type of composite material not sure what it was tho.
kinda like a plastic/fiberglass mix.  I do not know where they got them from.  I know that did not help.
however you can just continue to use the metal ones by removing the standard metal bolt and useing a fiber/plastic bolt (path broken) should be able to get these at a bolt supplyer.
 

RE: Feeder riser clamp

Use the stainless steel option. With no induced magnetism, the heating of the clamp is negligible. A few years ago we installed a substation with 750 mcm single conductor cables.
The PVC conduits were strapped with stainless type "P" straps. This was the utility standard.
Yes, one cable per conduit.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Feeder riser clamp

 
I was certain www.alumaform.com had a riser product in common use by electric utilities that would fit your application but I can't seem to find it online.
  
 

RE: Feeder riser clamp

Go to
http://www.alumaform.com/equipment_mount.pdf
and scroll down to "conduit Standoff Brackets"
We used the unistrut at one end of the 5" PVC conduits and the Aluma-Form brackets at the pole end.
Thanks for the lead, busbar.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Feeder riser clamp


Thanks for the pointer, waross.  With aluminum channel to break the "magnetic loop/circuit", ordinary plated-steel conduit clamps could be used in place of non-ferrous material.
    

RE: Feeder riser clamp

I agree, busbar.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Feeder riser clamp

I'll second Marmite's suggestion. We have used the Emperor range on a few jobs; they are well made and easy to install according to feedback from the cable crew, and worth the slight cost premium over some other suppliers. Installation was to ladder rack in horizontal and vertical orientation.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Feeder riser clamp

I am just an electrician and this really beyond my scope of knowledge, but it is my understanding that is only an issue when you do not have all three phases within the same magnetic clamp.  Is my understanding incorrect?   

RE: Feeder riser clamp

resqcapt19;
It's sometimes called magnetic encirclement. Below about 200 amps it is not much of an issue. Above 200 amps things start to get hot. All three phases (plus neutral if used) should go through the same opening in a magnetic material. This may be a clamp, a conduit or a hole into a panel. The magnetic encirclement may be broken by using a nonmagnetic bolt on a two piece strut clamp if the two magnetic sides of the clamp do not touch.
If single conductor cables enter a panel through separate holes, the holes may be joined by a hacksaw cut. Now you have one oddly shaped hole, but it will avoid the heating.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Feeder riser clamp

Bill,
  Thanks.  I understand the issue with single conductors and ferrous materials that encircle the conductor.  I assumed that in this case we do have all of the circuit conductors within a single cable, and if that is the case, I still don't understand.  That would be a very common field installation.
Don

RE: Feeder riser clamp

(OP)
resq, regarding your initial post,that is correct, all phases are mounted separately. This is because of the size of the cable and conduit per phase. i.e two 15kV 2000kcmil cables in 4" conduit per phase.
  

RE: Feeder riser clamp

zazmat,
Thanks...that makes sense to me and I have seen the results when this is not done correctly.  When I see the word cable, I just normally think of multiple conductors, not single conductors.  
Can I ask another question?  Why such a big cable?  Wouldn't parallel smaller cables be more cost effective?   

RE: Feeder riser clamp

Quote:

To be more specific I need to clamp aluminum pipe about 3-4" containing two 15kV 2000kcmil shielded cables to the the riser pole. The concern is the circulating current in the clamp due to magnetic coupling.
This sounds like two single conductors per phase. I don't think that two 3c 2000kcmil cables will fit in a 3" coduit.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Feeder riser clamp

(OP)
waross you are correct. These are two single conductors per phase. 2-2000kcmil paralleled together. I apologize if my use of term cable threw everyone off.

resq,
I hope it answered your question as well.
Also, how many parallel conductors would you recommend?

This is not my project so I don't have much of the details as to what's the loading is etc.

I raised this question for my information and learning purpose.

The goal was to findout some clamps which can break magnetic coupling when there's only one phase going through them, and not act as CTs with circulating current running in them. I am not much concerned with the size of the cables or paralleling techniques.
  

RE: Feeder riser clamp

Parallel conductors are common on low voltage, but not at 15kV. Much more insulation is needed, semi-conductor, etc.
And nothing gained since a single faulted cable will still take out the circuit.

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