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Associate

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2 pole or 4 pole : Which motor is a better choice?

04/22/2022 6:15 AM

Considering 50Hz power supply, I know 2 pole motor will run around 3000 & 4 pole around 1500rpm, but which one is better in long run from maintenance perspective or reliability or any other angle?

I have 2 pump-motor vendors, one is giving 2 pole motor other giving 4 pole motor. Power rating is same. And yes, efficiency is not a problem, both are IE3 class. Which one would be a better choice?

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#1

Re: 2 pole or 4 pole : Which motor is a better choice?

04/22/2022 8:08 AM
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#2

Re: 2 pole or 4 pole : Which motor is a better choice?

04/22/2022 11:16 AM

..."If the flow rate is small (under 4L/S) and the pressure is relatively high (greater than 150 kPa) it is most likely that a 2 pole motor-driven pump selection will offer superior performance and efficiency compared to 4 pole. This situation quite often applies to heating water applications where flows are low, pressure is reasonably high and they typically run for less time than cooling water pumps.

If 4 pole motor-driven pumps are considered for these low flow/ high pressure situations, the selection is often very inefficient, beyond the acceptable range of BEP and fraught with potential issues such as cavitation."...

https://masterflow.net.au/should-my-pumps-be-4-pole-or-2-pole-masterflow-solutions/#:~:text=The%20Performance%20and%20Efficiency,efficiency%20compared%20to%204%20pole.

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Guru

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#3

Re: 2 pole or 4 pole : Which motor is a better choice?

04/23/2022 1:42 AM

You don't provide any data on the capacity of the pump/ motor combination or f it is direct drive or belt drive.

For small motor pumps 2 pole may be better than 4 pole but ask yourself why large pumps are almost always 4 pole motors. Having worked on oil and mining applications with pumps then the common size of motor is 4 pole. 2 poles were only used on small demand domestic type situations. Pumps I have worked on run into the hundreds of CMH and all were 4 pole or 4 pole with VFD.

The pumps are designed to run at a speed and capacity which meets the demands of the load and the motor. Seals running at higher speeds will fail more rapidly especially if there is a loss of cooling medium. If the seals run on pumping media then any contamination will also effect the smaller high speed seal more profoundly than the larger slower running seal. Bearings will also have more problems with their seals and lubrication at the higher speeds.

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#4
In reply to #1

Re: 2 pole or 4 pole : Which motor is a better choice?

04/23/2022 2:20 AM

You are the owner of the pump. You know better than any one else what speed is best suited to your pump unless until you are purchasing pump motor as a single unit. In case it is single unit ,then the dimension of both, 2pole and 4 pole, would be different. 2 pole set will have lower diameter and longer length compared to 4 pole set. 4 pole set will have higher diameter and shorter length. You have to decide which one suits you better. Carbon brushes (if the motor hame brushes) would have comparatively shorter life due to higher rotor speed.

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#5

Re: 2 pole or 4 pole : Which motor is a better choice?

04/26/2022 7:30 AM

There sorts of questions are best answered by the maintenance team at the facility where the motors operate, for that is where the available experience with which to answer it can be found. That experience is based on local conditions.

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