Difference between 2 pole motors and 4 pole motors
Main difference
The main difference between 2 pole motors and 4 pole motors is that 2 pole motors have only one pair of magnetic poles while 4 pole motors have two pairs of magnetic poles.
2 pole motors v s. 4 pole motors
A motor is a device that transforms electrical energy into mechanical energy in the form of torque supplied through a shaft. It works according to the principle of electromagnetic induction defined by Michael Faraday. There are different types of motors, for example, 2-pole motors and 4-pole motors, etc.
A 2-pole motor is a type of motor that has two magnetic poles or a pair of magnetic poles, that is, north and south. On the other hand, 4 pole motor is the motor with two pairs of magnetic poles present in alternating orders i.e. north-south-north-south.
The number of poles has an inverse relationship with the speed, that is, the more the number of poles, the less the speed of the motor. So a 2 pole motor has more speed than a 4 pole motor. But, for heavy power, 4 pole motor is better than 2 pole motor. A gearbox below 3000 rpm is always required for a 2 pole motor. On the other hand, there is generally no need for a gearbox on a 4-pole motor.
A 4-pole motor has twice the work output of a 2-pole motor. The rotor of a 2-pole motor completes a single cycle for each cycle of the source. On the other hand, the rotor of a 4-pole motor completes only half a cycle for each cycle of the source.
Comparison chart
| 2 pole motors | 4 pole motors |
| A type of motor that has two magnetic poles or a pair of magnetic poles is known as a 2-pole motor. | A type of motor with 4 magnetic poles or two pairs of magnetic poles is known as a 4-pole motor. |
| Setting | |
| A 2 pole motor shows a north-south configuration. | A 4-pole motor shows a north-south-north-south configuration. |
| Speed | |
| A 2-pole motor has high speed due to the fewer number of poles. | A 4 pole motor has low speed due to a higher number of poles. |
| Efficiency | |
| A 2 pole motor is more efficient. | A 4 pole motor is less efficient. |
| Revolution per minute (RPM) | |
| A 2 pole motor has more RPM value. | A 4-pole motor has fewer revolutions per minute. |
| For heavy power | |
| A 2 pole motor is not good for heavy power. | For heavy power, a 4-pole motor is best. |
| Gearbox | |
| A gearbox below 3000 rpm is always required for a 2 pole motor. | Generally, there is no need for a gearbox on a 4 pole motor. |
| cycle completion | |
| The rotor of a 2-pole motor completes a single cycle for each cycle of the source. | The rotor of a 4-pole motor completes only half a cycle for each cycle of the source. |
| work output | |
| A 2 pole motor has less work. | A 4-pole motor has twice the work output of a 2-pole motor. |
| NPSHR | |
| A 2 pole motor has a higher NPSHR. | The 4 pole motor has a low NPSHR. |
| Energy consumption | |
| A 2-pole motor consumes less energy. | A 4-pole motor uses twice as much energy as a 2-pole motor. |
| Shape | |
| A 2-pole motor is cylindrical in shape. | The 4-pole motor is not cylindrical. |
| Torque | |
| 2-pole motors have 1.5 foot-pounds of torque per horsepower. | 4-pole motors have 3.0 foot-pounds of torque per horsepower. |
| noise performances | |
| A 2-pole motor has good noise performance. | 4 pole motor is not good noise wise. |
What are 2 pole motors ?
A 2-pole motor is a type of motor with two magnetic poles or a pair of magnetic poles. It shows a north-south configuration. A 2 pole motor is more efficient with high speed and higher RPM. At 60 Hz, a 2 pole motor has 3600 rpm. But it offers low torque, that is, 1.5 foot-pounds of torque per horsepower. In addition, it also consumes less energy and produces less work. This type of motor is not good for heavy power.
What are 4 pole motors ?
A 4-pole motor is a type of motor that has 4 magnetic poles or two pairs of magnetic poles. Shows a north-south-north-south configuration. A 4 pole motor is less efficient with lower speed and lower RPM. It shows 1800 rpm at 60 Hz. But it offers more torque, that is, 3.0 foot-pounds of torque per horsepower. It consumes more energy and runs twice as long as a 2-pole motor. This type of motor is good for heavy power.
Key differences
- A type of motor that has two magnetic poles or one pair of magnetic poles is known as a 2-pole motor, while a type of motor with 4 magnetic poles or two pairs of magnetic poles is known as a 4-pole motor.
- A 2-pole motor shows a north-south configuration; on the other hand, a 4-pole motor shows a north-south-north-south configuration.
- A 2-pole motor has high speed due to the fewer number of poles. On the contrary, a 4-pole motor has low speed due to a higher number of poles.
- A 2 pole motor is more efficient on the other hand a 4 pole motor is less efficient.
- A 2 pole motor has more RPM value; on the other hand, the 4-pole motor has less revolutions per minute.
- A 2 pole motor is not good for heavy power while for heavy power 4 pole motor is better.
- A gearbox below 3000 rpm is always required for a 2 pole motor; on the other hand, there is generally no need for a gearbox on a 4 pole motor.
- The rotor of a 2-pole motor completes only one cycle for each source cycle, while the rotor of a 4-pole motor completes only half a cycle for each source cycle.
- A 2 pole motor has less work output, on the other hand, a 4 pole motor has twice the work output as a 2 pole motor.
- A 2 pole motor has a higher NPSHR, while a 4 pole motor has a lower NPSHR.
- A 2-pole motor consumes less energy. On the contrary, a 4-pole motor spends twice as much energy as a 2-pole motor.
- A two-pole motor is cylindrical in shape; on the other hand, the 4-pole motor is not cylindrical.
- The 2-pole motors have 1.5 foot-pounds of torque per horsepower, while the 4-pole motor has 3.0 foot-pounds of torque per horsepower.
- A 2-pole motor has good noise performance, while a 4-pole motor does not have good noise performance.
Final Thought
The above discussion summarizes that a 2 pole motor is a more efficient, high speed motor with less work. On the other hand, a 4 pole motor is a less efficient motor with less speed but more work.