Case Studies

DeCrausaz and McConnell made several
measurements along the power line coming from
Enumclaw: the first at the supply end of the util-
ity grid, the second at the town of Greenwater
approximately 20 miles towards Crystal and the
third at Crystal. They made the first measure-
ments at a decommissioned sawmill five miles
outside of Enumclaw fed by the 57 kv utility line
that ultimately feeds Crystal. The voltage distor-
tion at the sawmill was only 1.9% THD on the
480 v secondary, indicating that the utility feed
to that point was good. DeCrausaz and McCon-
nell took more measurements in the town of
Greenwater, 20 miles closer to the ski area. On
the side of the Greenwater convenience store,
the distortion was 14 % with the lifts running
and 6 % with the lifts off. Greenwater is fed
from the 57 kv line transformed down to 12 kv
from the local area. Crystal is further fed from
this 12 kv line in Greenwater through a trans-
former to 34 kv. After passing through Greenwa-
ter the voltage is stepped up for the remaining
distance to the mountain, along underground
and overhead lines. The utility had a backup
2000 kw generator just off Crystal’s property at
4160 volts transformed to 12 kv to match the 34
kv delivery voltage that is then transformed to
12 kv for distribution around the ski area. Crystal
is primarily metered on this 12 kv line.
The utility felt that the problems were caused
by some of the old 12 kv underground line
located on the ski area. So, the team tested
this theory by starting the mountain’s 2000 kw
backup generator at night with no lifts running
and monitoring the voltage and current at one
of the power filters. With the generator on in
parallel (co-generating) with the utility, the 5th
harmonic current to the power filter reduced to
60 amps, 72 amps and 88 amps, on phases A, B
and C respectively. With the utility removed from
the circuit, the 5th harmonic current was further
reduced and balanced to 25 amps, 22 amps and
24 amps. This test proved the problem was on
the utility system between Greenwater and the
backup generator and not on Crystal’s property.
After further investigation, a 900 kvar-capaci-
tor bank was located on a pole near the Green-
water substation on the 12 kv line servicing the
town. The capacitors had been switched online
at the end of April for a still undetermined
reason. During the summer the C-phase fuse
had blown several times and been replaced.
The C-phase fuse was out and hanging down
when the capacitor bank was located. At that
point, the utility removed the remaining two
fuses and said it planned to remove the capaci-
tor bank from the pole so that it couldn’t be
inadvertently energized.
Later at the ski area, the following volt-
age waveform was recorded at Lift 11 with the
mountain shutdown for the evening. Note the
amount of distortion still on the utility system.
That evening at the ski area, all the power
filters were put on-line and measurements taken
to prove their health. The voltage distortion at
the area was reduced to 3.1 % THD. The next
day, technicians turned on all of the lifts with all
four filters and all of the pumping stations and
conveyors online. The voltage waveform below
is at Lift 11 with all the lifts and filters on line.
South Feeder
North Feeder
Enumclaw
Greenwater
57KV
57KV
NORTH
Greenwater
Substation
57KV
12KV
34KV
Crystal Mountain
12KV
2MW
GenSet
4KV
900 KVAR
Capacitor Bank
Weyerhaeurser
Plant 4KV
Lift 11 off. Filter off. All other lifts off. Utility caps off.
Lift 11 on, filter-3 steps. Lift 10 on, filter-3 steps.
Lift 9 on, filter-3 steps. Lift 3 on, filter-2 steps.
All other lifts running.
3 Fluke Corporation Power quality accountability