Measurement of No-Load Saturation Curve of a Synchronous machine at Stationary Condition

Abstract

The no-load saturation curve, a fundamental machine characteristic, is normally measured as the relation between field current and terminal voltage of a synchronous machine rotating at its rated speed.
In this paper, we propose a static method to measure the no-load saturation curve of a synchronous machine at stationary condition by changing the field current.
When testing a synchronous machine at stationary condition, large expenditures are required for such items as depreciation of the test equipment, test engineers, electric power, etc. Therefore, omitting the rotating test will reduce testing costs and delivery time.
In this paper, an experimental generator (2kW, 1500rpm) and a practical generator (1200kVA, 900rpm) are used to evaluate the no-load saturation curve for different types of synchronous machines, stationary rotor positions, field current excitation methods, etc. The results were confirmed to be satisfactory for practical use.
Further, the influence of higher harmonics of gap flux and a damper winding was examined and verified that they do not affect the measured values.