Impact of a 32000 HP refiner motor on Daishowa's existing power system and equipment

The power system at Daishowa's TMP plant in Quebec city was commissioned in 1989. The two-line plant comprised two primary, two secondary and three rejects refiners. the primary and secondary refiner motors are rated 24000 HP each, and rejects are rated 6700 HP each. For increased pulp production, Daishowa decided to replace the existing 24000 HP P2 refiner motor with a new 32000 HP motor. The existing refiner was large enough to handle the increased production. An impact study was carried out to ensure that the refiner could be started and operated within the power system constraints, without adverse effect on the existing distribution system. The study included: power system analysis including load flow, short circuit and motor starting; voltage flicker and starting methods; review of equipment rating; selection of new equipment; motor performance during acceleration; and installation constraints. This paper describes the methodology used for the study and solutions found to circumvent the problems associated with the application of large refiner motors.