How does the voltage at the motor field change when the O relay is disabled?

When the O relay is disabled, it interrupts the circuit that provides power to the motor field. This action decreases the voltage at the motor field because the power supply is cut off or significantly reduced. The motor field relies on the relay being active to maintain a certain voltage level necessary for its operation. When the relay is disabled, the circuit is opened, leading to a loss of voltage that would otherwise be present in the motor field circuit. This reduction prevents the motor from functioning correctly, highlighting the critical role that the O relay plays in maintaining proper voltage levels for motor operations.