20080905Response to Outage Comments.pdf

RECE'fVEO ~n.¡¡~IS"~18
208SEP -5 AHH: aa iFU' _ j ...
IDAHO 'PU8LiC', ,
UTlLlTlESCOMMlSSION
September 4, 2008 Al!u-E: -òe-oV
Avu -o-cB-o(
Jea Jewell, Commssion Secreta
Idaho Public Utilities Commssion
W. 472 Washington Strt
Boise, ID 83720
Re: Response to Power Outage Comments for the Towns of Culdesa, Lapwai and Stite
Dear Ms. Jewell:
In response to Commssioner Smith's rent question concerning the electrc reliabilty for the
towns of Culdesac, Lapwai and Stites, Idao, the Company has prepar the following:
As backgrund, SWT3 is the man Avista feeer frm the Sweetwater 11512kv substation. It
runs to both Culdesac and Lapwai at the 24kv voltage level and is trsform at eah town to
13kv via step down trsformrs. Kooskia 13kV (1299) is the feeer that prvides distrbution
service to the towns of Kooskia and Stites.
The causes of outages that ocured frm Deember 200 to August 2008 ar as follows:
Four weather relate outages cause by lightnng (th outages) and snow/ice loadng
(one outage) afecte the customers locate in Culdesac;
Th public relate outages caused by car hittng poles afecte the customers locat
in Culdeac;
An outage on the 115 kV trsmission line afecte all of the customers in Culdeac and
Lapwai; and
Two tr relate outages cause by weather blowing trs into distrbution lines afecte
par of the customers in Culdesac.
The outage durtions that ocur on the Trasmission and Distrbution systems servng
customers on the Sweetwater feeer raged from 17 minutes to twelve hour and 41 minutes. Of
those durons, 12 were sustaned outages of gratr than 5 minutes and 7 reorded momenta
outages of less than 10 seonds had also occur.
Oter outages ocur when the Sweetwater sub was rebuilt in 207. A vista ha severa
planed outages to integrte the new feer and constrct the new 115kv line to the sub. The new
substation will increas th ar reliabilty.
~
Page 2
In addition, it appe that the number of outages due to mechanical failur of 24kv Pin insulator
is rising on the SWT3 feeer. The towns of Culdesac and Lapwai ar afecte eah time an
insulator fails. Recnt insulator failur cause pole fies and subsequent customer outages. The
natu of the failurs is such that when one piece is repaire, it appear to strss the next insulator
"down-the-line', thus we ar seeing a domino effect of insulator failurs withn a relatively short
time fr. A vista is awar of ths problem and has prepar a plan to addess it. We have taen
the 8 miles of 24kv insulators and broken it into 4 setions. Ou plan is to tae a series of 4 hour
outages, utilize 4 crews and replac eah insulator. In ths way the work can be done safer and
faster.
Culdesac is fed frm a mid-line recloser at the 24kV to 13.2kV step-down trsformr. The
reloser has ben rently replac and should also increa reliabilty to the town of Culdesac.
The outage durtion that ocurd on the Transmission and Distrbution systems serving
customers on the Kooskia feeer raged from 21 minutes to th hour and 28 minutes. Of those
outages 11 were grr than 5 minutes and 7 reorded momenta outages of less than 10
seconds also ocur.
With repet to the two customers who commnte on outages at the public heang on August
27, 2008 in Lewiston, our records show that the Mock residence locate in Culdesac, Idao
experienced four outages durng the last 12 months. The Berr residence locate in Stites, Idao
experience two outages in the last 12 months.
If you have any fuer questions regarng ths issue, please contact Lida Gervais at
[phone].
Sincerely,~dr.-
Vice President, State & Federa Regulation
A vista Utilities
509-495-4267
kelly. norwood (g avistacoip.com
cc: Commssioner Redford
Commssioner Smith
Commssioner Kempton
Marlyn Parker - Consumer Afai