What does the voltage on the signal main primarily represent?

The voltage on the signal main primarily represents control power. In electrical systems, particularly in transit operations, control power is essential for the proper functioning of signaling equipment. This voltage is used to operate relays, switches, and other control mechanisms that ensure signals are correctly set or reset based on the operational status of the transit system.

Control power enables the communication and command signals to pass throughout the system, allowing for the coordination and safe operation of trains. This is vital for maintaining schedules, ensuring safety measures, and managing overall system efficiency.

While operational power is essential for the main functioning of equipment and the movement of trains, and safety power is critical for circuits that ensure the safe operation of the transit system, the signal main specifically focuses on the voltage needed for controlling signal operations. Power for communication can be a part of that control process but isn't the primary representation of voltage in the signal main.