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motor to generator
By wpowokal, Section Homebrewed Electricity Posted on Mon Jul 28th, 2003 at 07:40:56 AM MST
710 rpm motor

I have access to some motors with the following;
415v 710 rpm 3 phase, the stator has 16 slots, they have a delter symble on the nameplate and the ends of each winding are accessable.
I assume they are 8 pole motors and therefore are good candiates for conversion to generators. By my reconing they would start charging my system (24v)at less than 100rpm.
Unfortunatly the stator windings have been encapsualed in what apears to be expoxy resin. In their past life the powered roof vent fans in an alumina refinery.
Should I aim to use stator as is, or rewind?
Installing magnets into the rotor, assuming 8, what number of degrees should I aim for each magnet to cover?
The nameplate is unclear so I am unsure on KW rating but they have a 1.5" shaft. Meaning they are very industrial and would stand a large set of blades.
Any advice very welcome, regards Allan

motor to generator | 5 comments (5 topical, 0 editorial)

Re: motor to generator (none / 0) (#1)
by zubbly on Mon Jul 28th, 2003 at 09:37:02 AM MST
(User Info) www.zubbly.com

hello Allan, just read your posting. i think your name plate should read 1710 rpm, not 710 rpm. an easy way to determine number of poles in motor is as follows. dismantle motor and remove rotor. lay the stator on winding. connect DC power source to any two of the three motor input leads ( a small 12 volt battery charger works great ). hold a small compass against the stator and slowly go around the inside of the stator once. you will notice that the compass flips from north to south. use a piece of chalk and mark the poles. there will be an equal number of north and south poles. add up the number of north and south poles. this equals the number of poles for your motor. you are testing for the number of poles in one phase by doing this. 2-pole=3600 rpm,4-pole=1800 rpm,6-pole=1200 rpm, 8-pole=900 rpm, and so on. on 3600 rpm stators, you must hold the compass directly in the centre of the stator bore, or else the compass reading will be very eratic.

hope this helps--------zubbly

Re: motor to generator (none / 0) (#2)
by wpowokal on Tue Jul 29th, 2003 at 07:09:28 AM MST
(User Info)

Thanks Zubbly I will buy a small compas when next in town. Yes the maneplates are not very clear so you may well be right about the speed.

regards Allan
A life lived in fear is a life half lived.

Re: motor to generator (none / 0) (#3)
by Smithson on Tue Jul 29th, 2003 at 07:25:25 AM MST
(User Info)

Zubby: There is another way to figure the poles.
Frequency = nbr of poles x RPM/120 Smithson

[ Parent ]

Re: motor to generator (none / 0) (#4)
by zubbly on Thu Jul 31st, 2003 at 05:55:30 PM MST
(User Info) www.zubbly.com

hello Smithson, i was trying to explain to Allan how to check for number of poles in order to determine correct speed. i felt that his assumption that his motor was 8 poles was in jeopardy and did not want to see him use up many magnets to convert rotor. when name plate is damaged and winding is encapsulated, this is a good way to determine speed. your formula to determine frequency however is correct. a motor with 8 poles @ 60 cycle wood give 900 rpm at synchronous speed, and 450 rpm @ 30 cycle. i am assuming that Allan's motor is 60 cycle.

zubbly

[ Parent ]

Re: motor to generator (none / 0) (#5)
by wpowokal on Sat Aug 2nd, 2003 at 04:18:43 AM MST
(User Info)

Oh still confused. Having obtained a compas I determined a deflection for each 4th segment of 36.

These are 50 HZ motors, I checked the other 5 and all say 710 RPM? Don't know if I'm just hoping for a low speed motor or have one, oh well I will just have to free up the bearings reassemble it and throw some sparks at it. Thanks anyway

regards Allan
A life lived in fear is a life half lived.

motor to generator | 5 comments (5 topical, 0 editorial)

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