#### Mihai_F

##### 100 W

- Joined
- Oct 11, 2021

- Messages
- 127

Hello guys,

I have been searching the internet for a log while, about formulas and books how to calculate the windings of a 3 phase motor, i.e. nr of turns, wire thickness etc.

I found some good theory books, some good sites explaining stuff, but haven't found an actual practical example with real numbers and dimensions.

So i asked a friend that worked at a winding shop how do they rewind a 3 phase motor if they have only the stator with no windings on it (like someone dismantled it before going to rewind shop with it )?

He puled a book from a shelf, it is from 1967 called in Romaian "Cartea Bobinatorului de Masini Electrice" ~ The Book of Electrical Machine Winder (it is available in pdf on the net).

That book has all the formulas and practical examples how to do the winding job, like "from scratch" a 36Kw 500V 3 phase motor

I made an excel document that calculates all that, down to how many Kg of cooper wire are needed, if you know the motor configuration (PP & Slots) and the applicable winding scheme (search "motor winding calculator" on net, that gives a nice site that does that winding scheme).

Now that being said, in those formulas they recommend to set the max flux density for stator to an conservative level of 0.78Wb/m^2 (0.78 T), and that gives a certain number of turns per phase at a certain frequency and stator dimension, but if higher max flux is given, say 1,2Wb/m^2 for the same freq and stat dim the number of turns is smaller. That makes perfect sense but, in my experience if i rewinded a motor with more turns at same voltage had slower max rpm.

The thing is, that i have a motor that is winded kinda "HOT" in the saturation zone of the core, and i want to rewind it such way that i does not reach saturation, but keep the same power Kv, rpm, voltage all that, and those formulas baffle me a bit compared to what i experienced so far.

I know about the core loses and eddie currents, thinner laminations and stuff, that is another subject.

So what do you think about this, any motor gurus chime in?

i attached the excel with my current motor setup(first) and some wanted flux density that does not saturate(second)...

I have been searching the internet for a log while, about formulas and books how to calculate the windings of a 3 phase motor, i.e. nr of turns, wire thickness etc.

I found some good theory books, some good sites explaining stuff, but haven't found an actual practical example with real numbers and dimensions.

So i asked a friend that worked at a winding shop how do they rewind a 3 phase motor if they have only the stator with no windings on it (like someone dismantled it before going to rewind shop with it )?

He puled a book from a shelf, it is from 1967 called in Romaian "Cartea Bobinatorului de Masini Electrice" ~ The Book of Electrical Machine Winder (it is available in pdf on the net).

That book has all the formulas and practical examples how to do the winding job, like "from scratch" a 36Kw 500V 3 phase motor

I made an excel document that calculates all that, down to how many Kg of cooper wire are needed, if you know the motor configuration (PP & Slots) and the applicable winding scheme (search "motor winding calculator" on net, that gives a nice site that does that winding scheme).

Now that being said, in those formulas they recommend to set the max flux density for stator to an conservative level of 0.78Wb/m^2 (0.78 T), and that gives a certain number of turns per phase at a certain frequency and stator dimension, but if higher max flux is given, say 1,2Wb/m^2 for the same freq and stat dim the number of turns is smaller. That makes perfect sense but, in my experience if i rewinded a motor with more turns at same voltage had slower max rpm.

The thing is, that i have a motor that is winded kinda "HOT" in the saturation zone of the core, and i want to rewind it such way that i does not reach saturation, but keep the same power Kv, rpm, voltage all that, and those formulas baffle me a bit compared to what i experienced so far.

I know about the core loses and eddie currents, thinner laminations and stuff, that is another subject.

So what do you think about this, any motor gurus chime in?

i attached the excel with my current motor setup(first) and some wanted flux density that does not saturate(second)...

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