March 18, 2002

PureWave DSTATCOM^® Lets Mining Operation Peacefully Co-Exist With Its Neighbors.

Background

A mining operation located in Indiana produces minerals for the construction and agricultural industries. This facility utilizes rock-crushing equipment that can take raw material a foot or more in diameter and reduce it to five inches or less . . . or even powder, depending on the application.

Seventeen 480-volt motors are used in the machinery for this operation, ranging in size from 75 hp to 250 hp. A large number of fractional-horsepower motors are used as well. The simultaneous starting of this large motor load was causing voltage variations of 8% to 12% on the feeder serving the mining operation and over 800 other customers. Such variations far exceeded the 4% maximum flicker considered acceptable by the local electrical utility.

What did they do?

Several alternatives were considered:

• The facility could operate at less-than-full capacity,
• A new distribution substation could be built specifically for the mining operation, or
• A static compensator could be installed, enabling the mining operation to co-exist on the same feeder with the other customers.

The first two alternatives were not economically justifiable and were thus rejected.

An S&C PureWave DSTATCOM® Distributed Static Compensator rated ±2 MVAR was selected and installed, along with a parallel 2-MVAR capacitor bank. Together, they provide a controllable reactive range of –2 to +4 MVAR.

The results

As shown in the actual field measurements below, the PureWave DSTATCOM has practically eliminated flicker on the feeder. The PureWave DSTATCOM provided a first-year cost savings of over $600,000 compared to a new distribution substation, and allowed the facility to operate at full capacity.

Actual field measurements of system voltage 1.5 miles upstream of the rock-crushing operation.