What does the insulation class of windings establish limits for?

The insulation class of windings is crucial for determining the maximum allowable temperature that the insulation materials can withstand without degrading. Each insulation class defines a set of temperature limits, which directly impacts the current-carrying capacity. As the temperature rises, insulation materials can break down, potentially leading to electrical failures or safety hazards. Therefore, understanding the insulation class helps to ensure that the windings can safely operate within the electrical system without risking damage or reduced performance.

Considering the other options, while current capacity is influenced by the insulation class, temperature and pressure monitoring focuses more on the operational conditions of the generator rather than the winding materials. Voltage levels in the circuit pertain to the electrical potential but do not connect directly to insulation properties. Protection relays are important for circuit safety but relate more to the electrical system's protective measures rather than the specific classification of insulation in windings.