Rated Starting Performance of Solid Pole Synchronous Motors from Reduced Voltage Factory Tests

The starting performance of 5-60 MW solid-pole salient synchronous motors having 4 or 6 poles is discussed. The rated performance derived by voltage-scaling from reduced-voltage factory tests, is compared against onsite measurements and rated-voltage factory tests. Issues addressed by the paper are the need for: accurate but practical measurement methods, individual focus upon the average and the pulsating torques, stringent test floors procedures (when collecting reduced voltage tests data), reliable voltage scaling factors, correct interpretation of relevant Institute of electrical and electronic engineers guidelines, and finally, the role of the load (inertia) in defining the starting performance of synchronous motors. Shown is that even the best of existing voltage scaling methods do not allow a true estimation of onsite measurements due to the absence of the load (inertia) during reduced voltage factory tests. The electrical measurement method is found to be the most practical and accurate method for the measurement of pulsating torques. A need for clearer IEEE scaling recommendations that also consider the load in addition to voltage effects is corroborated.