What voltage is seen across the transformer primary in the schematic?

The voltage seen across the transformer primary is determined by the system's configuration and the specifications of the transformer itself. In many residential and commercial applications, a transformer may be connected to an input voltage of 240 volts to step it down for lower voltage usage, such as 120 volts for general appliances.

This specific choice indicates that the transformer primary is designed to operate with a line voltage of 240 volts, making it a standard rating for many electrical systems that require transformation for various applications. In scenarios where equipment runs at higher voltages, such as 480 volts, the transformer primary would be connected to the appropriate voltage level to ensure efficient function and safety.

Choosing 0 volts would imply that there is no power present, which doesn't align with operational conditions in a typical scenario where the transformer is being utilized. Understanding the context of how transformers work is pivotal, as they require specific primary voltages to function effectively in their intended role. Thus, selecting 240 volts accurately reflects a common scenario in HVAC systems that utilize transformers for voltage adjustments.