The expression "voltage regulation" as it applies to a shunt-wound DC generator operating at a constant frequency refers to:

Voltage regulation in the context of a shunt-wound DC generator typically refers to the ability of the generator to maintain a consistent output voltage as the load changes. Specifically, it is the difference between the no-load voltage (the voltage measured when no load is connected) and the full-load voltage (the voltage measured when the generator is supplying maximum rated load).

When a load is applied to the generator, the voltage tends to decrease due to the internal resistance and the armature reaction. Hence, tracking these changes in voltage as load is applied and subsequently released characterizes voltage regulation. Thus, fluctuations that occur when transitioning from load to no-load conditions effectively illustrate this concept.

This understanding highlights how shunt-wound generators react to variations. It clarifies that while the generator may strive for stable output, there are observable changes in voltage depending on whether a load is present or absent. Understanding these fluctuations aids in assessing the performance and reliability of the generator under various operating conditions.