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dcb 12-01-08 10:38 AM

previous engine was a tecumseh HSK635, 4700 rpm, 3.5 hp ~ 3.9 ft lbs.

I should take a torque and rpm reading on the electric motor i suppose.

dcb 12-23-08 07:07 PM

Wiring question

The 11 amp motor had a strong finish during some non wet days, throwing the snow quite far. But it finally lost most of its power and was tripping the breaker more often, and was making sparks where it wasn't supposed to :)

I took the motor mostly apart and noticed the varnish on the field windings was cooked and flaking off in chunks, and that seemed like where the fireworks was coming from by the burn marks also. I also noticed it was aluminum wire on the field (the rotor looked ok, don't have a growler handy).

More dissection revealed it was about 22 yards of 15 gauge aluminum on the field and it was shunt configuration.

So I figure 22 yards of 17 gauge copper magnet wire would be about equivalent magnetically speaking (same current and number of turns).

But I should consider going to 23 yards of 16 gauge, which would give me the same current but about 5% more turns.

Alas, I obtained a 2hp (5max, 13 amp) compressor motor in the meantime (compressor part disintegrated), series wound, should be interesting :) I also now have to figure out what to do with a 30 gallon air tank on wheels. :rolleyes:

TimJFowler 12-24-08 04:41 PM

Why not replace the 15 gauge aluminum wire with 15 gauge copper? I know that the copper has a lower resistance and greater current capacity. How else would the copper affect the motor's parameters (i.e. h.p., torque, etc.)?

I'm curious as I don't know much yet about modifying and rewinding electric motors.


dcb 12-25-08 11:54 AM

As you can probably tell, I'm learning as I go here :) But I really don't know what effect increasing the field strength will have, might run slower with more torque?

I have another candidate motor maybe, it is decades old. My grandpas old homemade table saw showed up at my sisters and this was on it. Could use some help figuring out if it will work. Just by sheer mass it looks like it should tear up the sidewalk but... :) I'm hoping the ratings were a lot more conservative a long time ago, but it could just be big and "weak".

Picture next to the compressor motor I'm putting the pully on at the moment, ran out of welding wire:

Data plate, the motor is ~14 inches long and 7 inches in diameter, Westinghouse:

dcb 12-26-08 09:25 AM

Ok, I think the big guy is a repulsion motor. It has brushes that connect to each other through the case. It is only of historical interest, LOL :)

It is pretty smooth, doesn't have the usual "Angry motor" sound, but it isn't drawing enough power to be a snowblower and weighs a ton. So gotta find another home for it.

larryrose11 12-27-08 04:19 PM

I have a Craftsman 10A snow thrower. Works great! It has a srew on the front, terminating in a paddle in the middle. Spins pretty fast.

davidbr13 12-29-08 08:23 AM

If you wind up rewinding the motor (no pun intended), then be sure to have a higher grade insulation baked on. sounds like that is what failed in the first place.

I agree you need a bigger motor, but probably not too much more. I have one of those motors, they were made for plug-in lawnmowers. They would be rated about 1-1.5 HP, as compared to the 3.5 gas engine that came out of your blower. Rewinding it probably won't gain too much power, but using copper could increase the cooling ability, which will help. Adding a dedicated cooling fan and using a higher rated insulation could also help. When motors are mass produced like that, they tend to make them as cheap as possible, and the aluminum wire may have been a concession to that.

You are correct if it is shunt wound then increasing field strength will reduce speed but give you more torque, which sounds like the right way to go in your case, since you need more oomph when you hit wet snow.

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