HomeMy WebLinkAboutElectric Board - Minutes - 02/21/2007Fort Collins Utilities Electric Board Minutes
Wednesday, February 21, 2007
Electric Board Chair City Council Liaison
John Morris 377-8221 Kurt Kastein
Electric Board Vice Chair Staff Liaison
Dan Bihn 218-1962 DeEtta Carr 221-6702
Roll Call:
Board Present
Chairperson John Morris, Vice -Chair Dan Bihn, Tom Barnish, John Graham, John Harris, Jeff
Lebesch and Alison Mason
Board Absent:
Steve Wolley
Staff Present:
Kraig Bader, Patty Bigner, Bill Bray, Brad Burke, DeEtta Carr, Eric Dahlgren, Joyce Grenz, Bob
Hoover, Tom Rock, Mike Smith and Dennis Sumner
Meetin¢ Convened
Chairperson John Morris called the meeting to order at 5:38 p.m.
Citizen Participation
There was no public comment.
Approve Minutes of November 15, 2006, Meetin¢
Board member Dan Bihn made a motion, seconded by Board Member John Harris to approve the
minutes of the November 15, 2006, meeting. The motion passed unanimously.
Welcome New Board Member
The Electric Board welcomes John Graham as its newest member.
Electric Reliability
Fort Collins Utilities Standards Engineer Manager, Kraig Bader, presented a quick overview on
the basic electric system. Starting with generation from Platte River Power Authority, electrical
current goes along the high -voltage transmission lines to the substation, then to feeder circuits
and then typically to a switch.
Electric Board Meeting Minutes
Wednesday, February 21, 2007
Page 2
There are two basic types of switches in the distribution system; one is a submersible and the
other is a pad mounted switch, which you've likely seen around town. From there, switches split
into smaller circuits and smaller cables that go into residential and commercial areas. Then the
electrical current travels to a 200-class amp circuit to transformers that bring it down from
medium voltage to whatever the secondary voltage is.
Mr. Bader passed around various underground electrical distribution equipment, including
examples of cable, elbows, and pictures of transformers and switches. Next, he shared a chart of
the top equipment failures by customer hours for the years 01/01/2001 — 12/31/2006. This was a
chart just for equipment failures. There are other causes, such as animal- related failures for the
remaining overhead lines (squirrels can cause problems). Equipment also can be hit by motor
vehicles. The next slide showed the typical submersible switch installation. A question was
asked to see if the vaults could be opened with the switches energized. Mr. Bader answered yes,
the switches are designed for live switching and loadbreak switching can be done.
Medium voltage underground cable (a sample was passed around) designs incorporate two semi -
conductive shield layers as well as an overall concentric neutral. Semi -conductive layers are
designed to control voltage stress in the bulk of the insulation.
A slide on cable failures showed:
Most end -of -life cable failures occur as a result of dielectric (insulation) failure;
Insulation failure mechanisms called "water treeing" are the usual failure
morphology; and
Cables are often hit by excavators and directional drilling operations, as well.
Cable dielectric failure mechanisms: Water trees in the cable insulation system are the primary
mechanism by which most end -of -life cable failures occur. Conditions for possible development
of water trees are electrical field, water electrical disturbances (voltage transients from switching
or lightning) and time in service. Mr. Bader reviewed several other charts on cable failures and
the different ways to chart them, such as by cable size, with normalized yearly failure date, FCU
total cable failures/year, cable failure rate comparison, seasonal failure patterns from another
underground utility, FCU cable failures as of 2003, FCU cable failures as of 2006,
and Weibull analysis and lognormal analysis of cable failures.
Loadbreak elbow failures are the most common failures. End -of -life medium voltage loadbreak
elbow failures, usually the result of dielectric failure. Dielectric failures occur when the
insulation can no longer hold up against the electric field stress that the elbow is under.
Loadbreak elbow failures also occur as a result of loose or cross -threaded electrical connections,
and as a result of damage during installation. Bushings are the "other side of the connection"
that elbows connect to. Bushings are used on junction, transformers, switches and insulating
standoff modules. Fort Collins Utilities do not see many junction failures relative to elbow
failures. Fort Collins Utilities purchases high -quality elbows to prevent failures, and elevate
condition of existing elbows through maintenance programs.
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Electric Board Meeting Minutes
Wednesday, February 21, 2007
Page 3
A question was asked as to how the City compares with other utilities. Mr. Bader stated that the
only thing they are seeing different from other utilities is that the overall quantity of failures is
quite a bit less for the City of Fort Collins. This may be due to the fact that we don't have a lot
of lightning in Fort Collins and very few overhead lines.
There is a difference between a transformer failure and a transformer overload. Generally you
can tell the difference by the transformer. If the transformer has been overloaded, a breaker will
cut out before it allows damage to the transformer. In transformer failures, arcing or burning is
visible. Failure modes for subsurface transformers are often more eventful than they are for
padmounted transformers because of the probability of combustible gas generation in the
insulating fluid. In some cases, these failure modes occur in transformer installations where you
can get water in the tank that can result in arcing or if there is a manufacturing defect. Fort
Collins Utilities keep an eye on this and have made a couple of design changes in the last few
years to address this issue.
A question was asked as to what drives Fort Collins Utilities' decision to put in a submersible or
pad mounted transformer. Mr. Bader answered that it is mostly aesthetics, but there is a down
side to submersible installations, so they have had to increase and improve the transformers for
submersible. For the same size load, the submersible is twice as expensive. The vault also is
more expensive to install than a pad mount, but sometimes the community wants a submersible
transformer because they don't want to see anything. There are three issues with transformers;
cost, performance and safety. The factor that has been adjusted here is the cost. Reliability
shouldn't be sacrificed.
Fort Collins Utilities has a well -designed outage statistics database that was created in-house.
The goal for average system availability is that it be available to the customer at 99.9886% or
higher. This is based on all of Fort Collins Utilities outages. It takes more than a minute of
electricity being off to count as an outage. On average, the goal is for each customer to
experience no more than one outage per year.
Election of Officers
Vice -Chair Dan Bihn made a motion to nominate John Morris as Chairperspm for the next year.
Tom Barnish seconded the motion. The motion passed unanimously.
Chairperson John Morris made a motion to nominate Dan Bihn as Vice -Chair. Tom Barnish
seconded the motion. The motion passed unanimously.
Other Business
Mike Smith, Utilities General Manager, gave a brief review of the reorganization that is going on
in the City of Fort Collins.
Bill Bray, Electric Planning and Engineering Service Manager, presented a short discussion on
Smart Meters and suggested that we do a more extensive review in April.
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Electric Board Meeting Minutes
Wednesday, February 21, 2007
Page 4
Chairperson John Morris suggested that we discuss the purpose of the Electric Board. He
suggested that the board members look over the handout and talk about issues at future meetings.
Future Agenda Items
Letter to Council regarding term limits.
Adjournment
The meeting was adjourned at 7:27 p.m.
y e Grenz, Electri Board Secretary
ME