Which function operates when a block load is applied?

The correct answer is related to how electrical systems respond when they experience changes in load, particularly block loads. When a block load is applied, the system must maintain proper voltage levels relative to the frequency of the supply. This is where the Volts per Hz relationship comes into play, which describes how the voltage should be regulated in correlation to the frequency to maintain steady operation.

When a block load, which typically represents a sudden demand increase, is applied, the electrical system adjusts the voltage output while keeping within the acceptable range of frequency. This relationship is crucial for synchronous generators, where maintaining a constant ratio of volts per Hz helps ensure the stability of the system and prevents equipment damage.

In this context, options like amperage regulation, reactive power compensation, and frequency modulation serve different functions that do not directly address the immediate response to block loads in terms of voltage and frequency stability. Amperage regulation deals more with managing current levels, reactive power compensation focuses on balancing inductive and capacitive loads, and frequency modulation is about varying frequency characteristics rather than the direct response to voltage changes under load conditions. These functions have their importance but do not operate specifically in the same manner as the Volts per Hz function during a block load scenario.