Re: Help w/ Chokes

At 10:25 PM 6/3/96 -0600, you wrote:
>From rwstephens-at-ptbo.igs-dot-netMon Jun  3 22:22:57 1996
>Date: Mon, 3 Jun 1996 18:11:57 -0500
>From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
>To: tesla-at-pupman-dot-com
>Subject: Re: Help w/ Chokes
>>Date:          Sun, 2 Jun 1996 22:25:20 -0600
>>From:          Tesla List <tesla-at-poodle.pupman-dot-com>
>>To:            Tesla-list-subscribers-at-poodle.pupman-dot-com
>>Subject:       Re: Help w/ Chokes
>>Reply-to:      tesla-at-pupman-dot-com
>>>From jim.fosse-at-bdt-dot-comSun Jun  2 21:51:14 1996
>>Date: Sun, 02 Jun 1996 18:03:39 GMT
>>From: Jim Fosse <jim.fosse-at-bdt-dot-com>
>>To: tesla-at-pupman-dot-com
>>Subject: Re: Help w/ Chokes
>>On Sun, 2 Jun 1996 00:25:25 -0600, Tesla List
>><tesla-at-poodle.pupman-dot-com>, you wrote:
>>>From: Wallace Edward Brand <webrand-at-dgs.dgsys-dot-com>
>>>Standards for Distribution Transformers, Overhead Type-- Sixth Report EEI
>>>Pub. No. 55-14, NEMA Pub. No. TR2-1956, May 11, 1956.  The exact title of
>>>the book is "Electric Utility Engineering Reference Book, Volume 3,
>>>distribution systems.  Effective February 1, 1989, Westinghouse transferred
>>>its intellectual property rights in the book to Asea Brown Boveri.
>>>They operate as ABB Power Systems Inc., Advanced Systems Technology, 777
>>>Penn Center Boulevard, Pittsburgh. Pennsylvania 15235-5927  I hope this is
>>>helpful.   The quoted statement appears at page 206.  Wallace Edward Brand
>>	Thank you, I was looking for the transient over voltage limit.
>>I'll check with the library about getting a copy of the book.
>>	jim
>Hi Jim and others,
>My 16 kV, 10 kVA pole pig has a test specification called B.I.L. 
>which I believe stands for Basic Impulse Level.  The nameplate says
>BIL 120,000 volts.  This I believe is the rating to look for in a 
>good Tesla-able power transformer, the higher the BIL the better.  It 
>must be linked to lightning induced transient survival.  Hope this is 
>of some use.
>Happy Coiling! rwstephens
Dear Jim:  If you are looking for the BIL (basic impulse insulation levels)
for distribution transformers, they appear in Tables 3 and 4 for
Oil-Immersed and dry distribution transformers respectively.  They are given
in "full-wave" and "chopped wave" values.  It is my understandingIt from an
expert I once worked with who teaches at Texas A & M, that the full wave is
one which rises to its maximum in 1.2 microseconds and then decreases to
half the maximum in 50 microseconds. I understand from the IEEE Standard
Dictionary of Electrical and Electronics Terms, that the chopped wave is one
that is discharged before or shortly after cresting, discharged to a zero or
practically zero level as a result of a flashover at an external lightning
arrester or some other protective device.  Table 3 gives the full wave crest
BIL level for a 15KV oil-immersed distribution transformer at 95KV (full
wave) and 110KV (chopped wave crest).  For a Dry-type transformer shown in
Table 4, an impulse test value is shown at 50KV for a nominal 15KV class
transformer.  A footnote states that "These are present-day values for both
full-wave and shopped-wave tests.  No standard impulse tests have been
established."  I hope this is more useful than my earlier post.  Wallace
Edward Brand