The 560 kW matched AC motor and drive replace a soft start and 30-year-old motor on a pump set at the treatment works, solving recurring failures caused by overheating bearings and so reducing maintenance costs. The pump set is one of three at the Mannofield site, which are used in a rotating duty, assist and standby configuration. The pump sets are critical to the treatment works. If they fail, the water supply to Aberdeen would be cut off. The motor was tripping out on overload, over-current and under-current. Tests showed that the problems with the motor were caused by its age. It was 30 years old and the bearings were heating up and failing.
Scottish Water’s electrical consultants, approached ABB-authorised provider, Quantum Controls, and requested an upgrade to an ABB variable-speed drive and matched motor. Quantum supplied a low harmonic drive to avoid introducing harmonics into the electrical network system as the preferred alternative to fitting separate harmonic filters.