A governor with a 0% droop is referred to as which of the following?

A governor with a 0% droop is referred to as an isochronous governor because it maintains the output frequency of a generator at a constant value, regardless of load changes. The concept of droop in governor control relates to the relationship between the generator output frequency and the mechanical input power. A droop setting specifies how much the frequency will drop as the load increases.

In the case of a 0% droop, there is no frequency drop as load increases; instead, the governor adjusts in such a way that the frequency remains constant. This is essential in applications where precision in frequency is critical, such as in standalone power systems or synchronized systems that require exact frequency maintenance.

Thus, an isochronous governor allows for seamless and instantaneous adjustments to load changes, ensuring steady-state frequency stability in the power system. This characteristic of immediate frequency regulation is what differentiates an isochronous governor from other governor types.