What could be a consequence of running generators under-excited?

Running generators under-excited can lead to a reduction in voltage support capability. In this condition, the generator does not supply enough reactive power (VARs) to the grid, which is essential for maintaining voltage levels. This can cause the voltage at the generator's terminals to drop, affecting the stability of the entire power system.

When generators are under-excited, they absorb reactive power from the electrical grid rather than supplying it. This absorption of reactive power can lead to a situation where there is insufficient reactive power to support the system voltage, potentially leading to voltage instability or even collapse in severe cases. Therefore, maintaining proper excitation levels is critical to ensure that generators can provide adequate voltage support and keep the power system stable.

Other factors, like enhanced operational efficiency or improved thermal performance, are generally not associated with under-excited operation; instead, they are more typical of generators operated at optimal excitation levels. As a result, understanding the implications of under-excitation is crucial for reliable power system operation.