Avista wanted to evaluate the voltage fluctuation that occurs during the motor starting condition and log chipping operation at a 1750 HP wood (log) chipper plant that is within proximity to a 115 kV to 23.9 kV distribution substation. Avista has specific voltage fluctuation (flicker) criteria along with ANSI and the State of Washington standards that need to be met for the evaluation and study of the plant voltage fluctuation. Commonwealth performed the evaluation and study for Avista utilizing Milsoft Windmil software to model the Avista feeder and motor connection.
A key component of this study was understanding the specific characteristics of the motor during start. Commonwealth built the study model from maps and information provided by Avista. The evaluation was performed on the motor start voltage fluctuation and compared against Avista criteria. Commonwealth evaluated the feeder alternatives and having the motor control significantly limit start conditions. Other parts of the project included reviewing and evaluating the voltage fluctuation during chip conditions, length of time for the motor to reach full speed, and the possible number of chipper fluctuations per hour.