In modern electronic devices, electric motors are indispensable core components. According to different power source types, electric motors can be divided into DC motors and AC motors, with AC motors further classified into three-phase motors and single-phase motors.
So what is a single-phase motor, including its working principle and starting methods, and let’s explore the role that film capacitors play in it.
A single-phase motor is a type of electric motor that uses single-phase AC power to supply electronic devices. With advantages such as simple structure, low cost, and low noise, it is popular in many fields including household appliances and industrial equipment.
Although single-phase motors are popular in many electronic devices, they have one drawback: they do not have self-starting capability and cannot start by themselves. They need to rely on capacitor or resistor starting devices to achieve single-phase motor startup, and this starting capacitor is a film capacitor.
A film capacitor is a type of capacitor constructed by using metal foil as electrodes, overlapping them with plastic films such as polyester, polypropylene, or polystyrene from both ends, and then winding them into a cylindrical structure.
In single-phase motors, film capacitors are typically used as starting capacitors or running capacitors, playing important roles in the starting and operating processes of single-phase motors:
Providing phase difference
The addition of film capacitors causes the current in the starting winding to have a phase difference with the current in the main winding, thereby forming a rotating magnetic field. The rotating magnetic field is key to the starting and operation of single-phase motors.
Increasing starting torque
By selecting appropriate capacitance values, the current angle in the starting winding can be increased, thereby increasing the starting torque, enabling single-phase motors to start smoothly even under heavy load conditions.
Protecting the motor
After startup, disconnecting the starting capacitor through devices such as centrifugal switches can prevent motor overheating and damage.
At the same time, the addition of film capacitors can also improve the motor’s power and efficiency, reducing the motor’s starting current and heat generation.
Film capacitors serve as starting capacitors or running capacitors for single-phase motors, playing important roles in motor starting and operation, providing power for electronic devices to work.
This article is provided by JYH HSU (JEC) Electronics. JEC is a research, development, production, and sales-oriented company specializing in manufacturing and selling various electronic components such as capacitors and resistors.
Post time: Jun-24-2025