Nate Electrical Practice Exam

For which purpose is a start capacitor used in electrical systems?

1. To increase current flow during start-up

2. To maintain constant voltage

3. To improve motor efficiency

4. To assist in motor starting torque

The correct answer is: To assist in motor starting torque

A start capacitor is specifically designed to provide an additional boost of energy to an electric motor during the crucial starting phase. When an electric motor begins to operate, it often requires more torque than is available from the main supply alone. The start capacitor temporarily stores energy and releases it as the motor starts, which helps to increase the starting torque. This is particularly important for motors that need to overcome inertia or load resistance at the initial start-up. This function is vital as many types of single-phase induction motors struggle to start under load without this extra torque. The temporary increase in current flow provided by the start capacitor allows the motor to reach a speed where it can then operate efficiently on its own, without relying on the capacitor. Other options reflect different roles in electrical systems. While increasing current flow during start-up and improving motor efficiency may be related concepts, they do not specifically define the primary role of a start capacitor. Maintaining constant voltage is typically not the function of a start capacitor either, as voltage regulation is usually managed through other components in the electrical system. Thus, the option highlighting the assistance in motor starting torque correctly captures the essential purpose of a start capacitor.