Heating, Ventilation, and Air Conditioning (HVAC ) Electrical Practice Test

In which configuration are capacitors connected to the start winding of a motor?

1. In parallel

2. In series

3. In combination

4. In isolation

The correct answer is: In series

In many single-phase induction motors, capacitors are used to improve the power factor and create a phase shift necessary for starting the motor. These capacitors are typically connected to the start winding of the motor to provide the necessary boost during startup. When capacitors are connected in series with the start winding, they increase the voltage across the winding, allowing for a greater torque to be developed. This configuration ensures that the start winding operates effectively within the circuit, contributing to the overall performance of the motor during its initial startup phase. Connecting capacitors in series, rather than in parallel, means that the total capacitance is determined by the formula for capacitors in series, which is beneficial for optimizing the performance characteristics of the motor. It allows the motor to achieve the required phase shift between the current in the start winding and the current in the run winding. The other configurations such as parallel, combination, or isolation do not fulfill the necessary operational requirements for capacitor functionality in a motor's start winding, as they would not effectively create the required phase difference or voltage enhancement needed for proper motor startup.