Jeff Hildreth, Electrical Engineer, BPA: We have one of the nicest high voltage labs in
North America.
George Gela, Technical Executive, Lenox Lab, Electric Power Research Institute: We selected
this one because of its capabilities.
Hildreth: Basically, the purpose of the high voltage lab is to make sure that we keep the
power on the power lines. And with the cascade transformer we can produce 1.1 million volts.
And we use that to test things like insulators, hot sticks, transformers, capacitors, bushings
to make sure that they can withstand those higher voltages. So we do quality assurance
tests; we do safety investigations; we do failure analysis on equipment that’s failed.
So those are a few things that we do. And then the other type of tests that we do is
the impulse generator, which is behind a cloth over there. We’re protecting it because
of the testing that we’re doing today. But with that we can produce lighting here in
the building. That models when the lightning strikes our transmission lines — we want
to make sure that they can withstand that and all the equipment associated with it can
withstand the lightning strikes.
We do tours all the time, in fact, not only BPA employees, but we have students come through
here ranging from middle school all the way through college. We’ve hosted industry groups
here … we get a lot of Doctor Frankenstein references (scary laughing).
You can think of the high voltage lab as being able to produce really high voltages but with
a small amount of current. So we can produce 1.1 million volts at about three quarters
of an amp. And since this is a special test that we’re doing here today, we needed a
medium amount of voltage and a medium amount of current, and we needed the big high bay.
So we ran the special feeder cable from the medium power lab into the high voltage lab,
temporarily for this test.
EPRI is the Electric Power Research Institute, and it’s a utility funded consortium that
does basic research in the power industry. And Bonneville Power is a member of EPRI,
meaning that we spend money and in return we get results of their research. And this
is a project that we’ve been contributing to through [BPA’s] Technology and Innovation
Office, but we’re also contributing to the actual testing in this case.
Gela: The goal of the project is to develop equations, develop guidelines for protection
from arc flash, protection for the workers, the live-line workers who may be on a structure
during an unintended flashover. There have been several incidents of insulating tools,
hot sticks, flashing over. Fortunately, [there have been] no fatalities or very, very serious
incidents. So in that respect this is a very important issue; both for safety and in the
understanding of what protective measures or protective clothing should be used.
Hildreth: So when you have a short circuit on the power system, you create an arc. And
the arc is basically plasma — it’s the same as the surface of the sun, it’s super
hot. And it’s a hazard because it can burn you. And so what we’re trying to do here
is reproduce those conditions. And so we’ve created a tower that’s got a conductor and
an insulator just like any other tower. And we’re actually causing that insulator to
flash over, producing an arc. Then we measure the temperatures around it to see what the
exposure to the worker would be. And what we’ll use that for is to determine what
sort of protective clothing our workers have to wear to protect them against that.
It’s a difficult test to do; it’s never been done before in this way. And there are
a lot of unknowns.
Gela: And we are trying to understand the behavior of the arc; the locations which are
more prone to high incident energy and lower incident energy.
We had some expectations that the exposure levels would be lower than predictable equations.
So no really significant surprises, we’re just learning details of the behavior of the
arc in situations where tests have not been performed in the past.
Hildreth: The arcs that we’re producing here today are not likely to burn someone.
But what they can do is validate the models that are used to calculate the exposure of
the workers at higher arc currents. Unfortunately, to actually reproduce the burning conditions,
we would have to cause a system disturbance, and our customers don’t like that for some
reason.
Dave Childs, Research Engineer, EPRI: Basically what we’re trying to do is get an image
of a guy up on the bridge.
Pete Anderson, Electrical-Mechanical Test & Development Craftsman, BPA: I guess we
could do that.
Gela: We have a very good working relationship with Bonneville, with this laboratory. And
this is an opportunity to do real research. And that’s a very, very good working atmosphere
and scientifically very encouraging.
Hildreth: There were a lot of unknowns and the results seem to validate the assumptions
in the models that we’ve seen so far.
With this project, BPA is using the BPA laboratories to establish a leadership position and to
offer to the industry expertise that nobody else can offer. And through that we are going
to make our linemen, and linemen all over the country and possibly the world, safer
as a result.