First of all study the nameplate. Is this a single phase unit or three phase?
If single phase the previous answer is likely correct. And there are ways to either extend the connecting paddles or add more.
If it is three phase look to see if there is a mid-winding tap for a third voltage...
The biggest issue may be if you are feeding the transformer with any length of Underground Cable. We had such a ferroresonance issue that we now spec all of our pad-mounted transformers with LBOR switches.
If that is not possible use a three phase device to protect the primary cable system...
As has been brought up previously by allowing the skirts to touch is not the recommended practice.
We avoid this by installing a piece of 4in copper bus drilled to NEMA hole pattern. In an overhead application we also include a bail off one side to hang an arrestor, thereby eliminating any...
In the design of the transformer and substation was there a fault current study done? Where do you want the zero sequence currents to go. Typically protection engineers like to see the zero sequence currents return to the source transformers of the system, not to through the load transformers...
For those concerned with Ice and Wind loading on conductors and structures as it relates to applying the National Electrical Safety Code (NESC) please refer to the 2005 edition of ASCE 7 that has just been published. The 2007 edition of the NESC will include this map.
When looking at the ability to calculate the fault currents and capacity of the bank you need to keep the following in mind:
1) You are typically dealing with transformers of vastly different sizes. Something like 50 kVA and 15 kVA or any other combination. As a result when doing per unit...
As you know in the underground utiltiy systems there are generally two classes of systems: URD - 200 Amps or less and the 600 Amp systems. These are classified by the ratings fo the accessories that are available such as terminations and splices. If there is a chance that moisture may get into...
If you can get access to Pacific Gas & Electric's design manual there is a great section on diversity of loads. Puget Sound Energy also has a good discusion on the subject.
I see that we have had a wonderful discussion on theory and transmission lines.
The simplist method of limiting the amplitude of reflected wave is the installation of arrestors on the end of terminal lines. This would apply to both transmission and distribution.
I might suggest that the...
The bank you describe is usually provided for small commercial facilities that typically have single phase load in addition to a limited amount of three phase load.
If you look at the bank I would guess that one transformer is quiet a bit larger than the other. Something like a 50 kVA (likely...
There is fishtape on the market that has a tracer wire included. The idea being you could put a tone on it and trace it with a reciever.
Try FiberTek Tracer tape: http://www.fibertekinc.com/pull_details.cfm?ID=5
Even though you did not state it specifically I must assume you are referring to Transmission Class switches (55kV and above).
We have what I might call 3-1/2 versions of transmission line switches on our system. Arcing horns (for droping line charging current), Vacuum bottle switches (for...
Your question is a good one. My response makes the assumption that your firm falls under the ANSI C2 - NESC instead of NFPA 70 - NEC. In distribution utility applications within a residential setting you can plan to overload transformers up to 200% or more of nameplate. This is depending of...
A couple of years ago I had to research and create a specification for bidding 230kV NCI's. A good reference is:
Outdoor Insulators
Authors: Ravi Gorur, Edward A. Cherney, & Jeffery T. Burnham
Copywrite 1999 by Ravi S. Gorur, Inc., Phoenix, Arizona 85044, USA
Specific to corona rings you...
When it comes to Personal Protective grounds you are treading on a sensitive area.
Refer to ANSI Standard F855 for sizing of conductor and clamps.
You will need to know what your available fault current is in order to size the components properly along with a good idea as to how quickly your...
Any of the possible sources you mention may be a problem. Any "shorts" that would cause a draw on voltage to a point of effecting other devices will likely be at a higher temperature than it should be at the point of the "short".
If you can not find a source inside your...
