What device allows you to control when the current will flow in a circuit?

The device that allows control over when current will flow in a circuit is the control relay. A control relay functions as an electromechanical switch that opens or closes circuits, enabling the control of electrical power to other devices. When a certain condition is met, such as an input signal or a specific voltage level, the relay activates, allowing current to flow or stopping it, depending on how it is wired within the circuit. This ability to control the timing and sequence of electrical power is critical in motor control systems, where relays are often used to start or stop motors or to control various electrical loads based on user inputs or automated signals.

In contrast, an output device is designed to perform a function based on signals received but does not actively control the flow of current in the same way a relay does. A power transformer changes the voltage level in a circuit but does not regulate when current flows. An input device collects information or data but does not influence the flow of current in a circuit directly. Understanding the role of a control relay is essential for effective motor control and the design of electrical circuits.