Case Studies

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Application Note

F r o m t h e F l u k e D i g i t a l L i b r a r y @ w w w . f l u k e . c o m / l i b r a r y

Operator: Bill McConnell,

Var+Technologies and

Vaughn DeCrausaz, Starboard Electric

Measuring tools: Fluke-RPM Recorder,

ScopeMeter®, 41B Power Harmonic Meter

Inspections: Power quality/harmon-

ics logging at site, voltage distortion at

multiple feeder lines

Power

Quality

Case

Study

Finding a Power Quality needle

In a 30-mile haystack

At the end of April 2005,

Crystal Mountain Resort in

Washington suffered cata-

strophic failure of two power

filters associated with their

chair lifts. The ski resort

had just closed down for the

season. Maintenance person-

nel were doing the end of

the season maintenance and

cleanup when they smelled

the overheated reactors on the

power filters. Crystal Mountain

has four Var+Controls harmonic

power filters located in the lift

houses of their highest horse-

power chair lifts. All of the filter

units are programmed with two

fixed steps to adjust to loading

and power conditions to absorb

harmonic distortion, and the

rest of the steps automatically

turn on to obtain unity power

factor for the greatest electrical

efficiency when the lifts are

in operation.

Crystal Mountain’s elec-

trical personnel measured

the harmonic current in the

power filters to determine the

damage to the units. With

the help of Bill McConnell of

Var+Technologies, the team

found that only the C-phase

reactors in two of the power

filters were damaged. They

replaced those reactors and

continued investigating the

cause of the failure throughout

the summer. The filters were

louder than usual but seemed

to work.

At the start of the 2005

– 2006 ski season, the elec-

trical maintenance person-

nel noted that, as more chair

lifts were brought on line, the

more overloaded the power

filters became. They turned the

filters off in an attempt to save

the equipment and decrease

the noise and smell in the lift

houses. With the power filters

off line, the lift dc drives were

noisy, pumping systems on the

mountain malfunctioned, vari-

able frequency drives on

Photo by Don Svela

Summary of content (4 pages)

PAGE 1
Finding a Power Quality needle In a 30-mile haystack Application Note Power Quality Case Study Measuring tools: Fluke-RPM Recorder, ScopeMeter®, 41B Power Harmonic Meter Operator: Bill McConnell, Var+Technologies and Vaughn DeCrausaz, Starboard Electric Inspections: Power quality/harmonics logging at site, voltage distortion at multiple feeder lines Photo by Don Svela At the end of April 2005, Crystal Mountain Resort in Washington suffered catastrophic failure of two power filters associated with their
PAGE 2
conveyors tripped off-line and data capture credit card systems failed. At that point, the team called Bill McConnell of Var+Technologies and Vaughn DeCrausaz of Starboard Electric to help troubleshoot the ski area’s overall power system. Given the approaching Thanksgiving and Christmas holidays, finding a solution was of paramount importance. On the way up to the ski area, DeCrausaz took a measurement with a Fluke 41B power meter at an outside receptacle of a convenience store in Greenwater.
PAGE 3
DeCrausaz and McConnell made several measurements along the power line coming from Enumclaw: the first at the supply end of the utility grid, the second at the town of Greenwater approximately 20 miles towards Crystal and the third at Crystal. They made the first measurements at a decommissioned sawmill five miles outside of Enumclaw fed by the 57 kv utility line that ultimately feeds Crystal. The voltage distortion at the sawmill was only 1.
PAGE 4
Lessons learned from this adventure: • Have a good working relationship with your utility company. Without their help this problem would not have been isolated, located and solved. • Have good electrical drawings of your facility and surrounding area as far back toward the source as possible. Visually check and update the documentation periodically. • Pay particular attention to the utility’s equip- ment as far back as 50 miles from your facility.