The external characteristics of a synchronous generator generally refer to the curve of the voltage variation at the generator terminal when the load current changes while the internal electromotive force remains constant. The main test is the longitudinal axis synchronous reactance of the generator, that is, the internal impedance of the generator, which is an important indicator of the load-carrying capacity of the synchronous generator. However, nowadays, synchronous generators mostly adopt thyristor rapid excitation and damping windings, and their longitudinal axis synchronous reactance is mostly a transient value, which is far less than the steady-state value. In addition, due to the regulating function of the excitation system, the external characteristic can be artificially manufactured and can be positive or negative. A positive external characteristic means that the terminal voltage of the machine decreases as the load current increases, while a negative one means that the terminal voltage increases as the load current increases. Generally, the excitation system can be adjusted within the range of ± 15.
Insulation fit The voltage protection level of the primary electrical system is that, in the event of lightning strikes or operational overvoltage, the insulation levels of conventional transformers, generators, and lines are insufficient to withstand them. Components such as lightning arresters and capacitors are needed for protection. The coordination between the action value, action delay of the lightning arrester and the insulation withstand voltage capacity of the main equipment components, especially the impulse withstand voltage capacity, is called insulation coordination. The requirement is that the lightning arrester must operate before the insulation of the main equipment is damaged. When there are multiple components with different insulation levels, different insulation protection components must also be equipped for different components. The coordination of these protection components is also a major issue.
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Post time: Jan-12-2026