What is a 1-Phase Electric Motor?

A 1-Phase Electric Motor is an electric motor that uses a single-phase alternating current (220V) power source, suitable for residential electrical systems and low-power equipment. With a compact design, easy installation, and operation, the 1-Phase Electric Motor is widely used in households, small and medium-sized mechanical workshops, and light industrial machinery. Thanh Thai Motor specializes in providing high-quality 1-Phase Electric Motor lines with long-term warranties, well-meeting users’ technical requirements.

Structure of a 1-Phase Electric Motor

The structure of a 1-Phase Electric Motor is relatively simple. Basically, a single-phase electric motor is divided into two main parts: the stationary part (Stator) and the rotating part (Rotor). Every component in the 1-Phase Electric Motor plays an indispensable role in generating motion.

Stator (Stationary Part)

The stator is the foremost important part. The stator is the stationary component responsible for creating a magnetic field that helps the 1-Phase Electric Motor operate stably.

• Core: The core is made of multiple thin electrical steel sheets, ranging from 0.35mm to 0.5mm in thickness, precisely slotted and assembled into a sturdy cylinder. The core functions to conduct magnetism for the motor while reducing energy losses caused by eddy currents. As a result, the 1-Phase Electric Motor operates more durably and efficiently.
• Windings: The windings are made of enameled copper, placed in the core slots. Typically, the stator of a 1-Phase Electric Motor has two main coils: the run winding and the start winding. When powered, these two coils create a fluctuating magnetic field, which is the basic principle helping the 1-Phase Electric Motor run.

Rotor (Rotating Part)

In the overall structure of a 1-Phase Electric Motor, the rotor is the moving part responsible for generating torque. When clearly understanding what a Single-Phase Electric Motor is, you will see that the coordination between the stator and rotor is the decisive factor in the motor’s operational capability.

• Core: This core is made from assembled thin steel sheets with slots to place conductors or windings.
• Windings or Conductors: In the most common structure of a Single-Phase Electric Motor, the rotor is usually of the squirrel-cage type. Aluminum or copper bars are placed into the slots of the core, with both ends short-circuited by short-circuit rings.
• Capacitor: Although not located directly on the rotor, the capacitor plays an extremely important role. Thanks to the capacitor, the current in the auxiliary winding and the main winding are phase-shifted from each other, forming a rotating magnetic field that helps the motor self-start. Depending on the design, a 1-Phase Electric Motor can use a start capacitor or a run capacitor to increase working efficiency.

Operating Principle of a 1-Phase Electric Motor

The operating principle of a single-phase motor is essentially a “priming” process to create rotation. When plugged in, the main winding only generates a pushing force (pulsating magnetic field), which is not enough to make the machine spin by itself.At this point, the auxiliary winding and capacitor act as a priming push. The capacitor helps the current in the auxiliary winding run out of phase compared to the main winding, creating a swirling force (rotating magnetic field). This swirling force acts on the rotor core, helping it start moving. Once initial momentum is established, the motor will automatically maintain stable rotation to work.

Classification of a 1-Phase Electric Motor

Classification by Power

1-Phase Electric Motor under 3.7kW: This is the most commonly used group of products in household appliances and light industry such as water pumps, air blowers, mini air compressors, bench drills, etc. The advantages are power saving, ease of use, and simple maintenance.

1-Phase Electric Motor over 3.7kW: This is a higher power motor line, used in machinery requiring strong pulling force such as presses, woodworking machines, small conveyors, etc. The motor operates powerfully, withstands loads well, and is still easily connected to residential power sources.

Classification by Product Type

Brake Motor:Brake motors are integrated with an electromagnetic brake system to help stop the motor quickly when power is cut. This type is suitable for machinery requiring precise stopping such as stamping machines, cutting machines, small lifting equipment, etc., providing high safety and control.

1-Phase Hydraulic Pump: The hydraulic pump uses a 220V household power grid, specialized for lifting systems, small hydraulic presses, or lifting tables. Compact design, easy to install in places without 3-phase electricity while still ensuring stable pressure.

1-Phase Electric Motor Price List at Thanh Thai Motor

Quotations for a 1-Phase Electric Motor are typically classified based on power (kW or HP) and rotational speed. Unit prices will vary depending on whether you choose an aluminum housing or cast iron housing line, as well as the quality of the windings and internal capacitor system. You can refer to detailed rates by each power range and mounting style right in the price list below:

Things to Note When Buying a 1-Phase Electric Motor

• Distinguish between “aluminum housing” and “cast iron housing”:
  • Aluminum housing: Lightweight, fast heat dissipation, aesthetic look. Suitable for machines that need frequent movement or installation in cool, airy places.
  • Cast iron housing: Heavy, sturdy, resistant to impacts and harsh environments (dusty, humid). If installed fixedly for winches or crushers, cast iron housing should be chosen for durability.
• Check copper wire quality: This is an important factor of the motor. Prioritize brands committed to 100% heat-resistant copper wire. Aluminum wire or aluminum-alloyed copper motors are usually much cheaper but run hot quickly, burn easily under heavy loads, and are very difficult to rewind when damaged.
• Capacitor specifications (run and start capacitors):
  • Start capacitor: Helps the machine start powerfully (starting torque).
  • Run capacitor: Helps the machine run stably and saves electricity.
• Rotational speed (RPM)
  • 2 poles (2P): Speed about 2800 – 3000 RPM (runs very fast, used for cutters, water pumps).
  • 4 poles (4P): Speed about 1400 – 1500 RPM (runs slower but has strong pulling force, used for grinders, crushers).
• Check Amperage: When purchasing, you should check the nameplate to see what the rated current (A) is. When the machine runs no-load, the amperage must be much lower than the rated current. If running no-load and the amperage is already close to the level stated on the nameplate, that motor has poor efficiency or under-wound coils.

You can visit the comprehensive video page of the electric motor video category to watch more tutorial videos, product introductions, monthly price quotes, etc., performed by the technical expert team of Thanh Thai Motor.

Frequently Asked Questions

How to distinguish between a run capacitor and a start capacitor on a 1-phase motor?

The start capacitor only operates in the first few seconds to create starting torque and will be disconnected by the centrifugal switch once speed is reached. The run capacitor operates continuously throughout the machine’s operation to compensate for power and cool the windings. Incorrect installation or capacitor failure will cause weak starting, humming noise, or fast burning of the start winding.

What is the simplest wiring method to reverse the rotation direction of a 1-phase electric motor?

Unlike 3-phase motors which only require swapping 2 power wires, reversing a 1-phase motor requires intervening in the wiring diagram between the Run winding and the Start winding. You only need to keep the power wire into the Run winding intact and reverse the two ends of the Start winding (or vice versa).

Why are 1-phase motors often difficult to start or overheat when used in weak voltage areas?

1-phase motors are very sensitive to voltage. When the grid voltage drops below 200V, the starting torque drops sharply, causing the motor to fail to overcome the load’s inertia, leading to stalling and extremely rapid heat generation in the windings. In this case, you should upgrade the power supply wire cross-section or use an additional voltage stabilizer to ensure the motor operates durably and does not burn out due to voltage drop.