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Author Topic: Need a 5 hp motor.....  (Read 4206 times)

ottawavalleyboy

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Need a 5 hp motor.....
« on: January 29, 2012, 11:17:06 PM »
To run as a generator, 3 phase 1700 rpm or so ....but what I have is a 10hp 3 phase 3450 rpm motor.
Silly question but, can I just run the 10hp motor at half speed or is this wishful thinking?

Edited to add I just found my answer......"it won't generate electricity unless spun slightly faster than it's rated speed as a motor"
Shucks, I thought I had a freebie there for a second.
« Last Edit: January 30, 2012, 01:53:02 AM by ottawavalleyboy »
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Pete_b

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Re: Need a 5 hp motor.....
« Reply #1 on: January 30, 2012, 09:18:32 AM »
If you have excess power then speed the motor up with the gearing so that it runs at the right RPM with the engine running at half speed
Pete
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ottawavalleyboy

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Re: Need a 5 hp motor.....
« Reply #2 on: February 13, 2012, 02:40:49 AM »
I don't have more than 7.5 hp to play with but it's a big old Lister with flywheels.

Anyhow I have done some more looking & have found a Leeson single phase 230 vac motor 5hp at 1740 rpm 21/23 amps
which should give me around 5000 watts.

It's new secondhand which means no tax and local which means no shipping costs so at 400 bucks it
looks pretty good against a st head but there's a lot I don't know about generator heads & converting
one of these to do what a st head does may be more money and/or trouble than it's worth.... does
anyone know what's involved?
« Last Edit: February 13, 2012, 02:46:00 AM by ottawavalleyboy »
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ronmar

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Re: Need a 5 hp motor.....
« Reply #3 on: February 13, 2012, 03:05:35 PM »
Induction motors as generators have a few drawbacks.  They are not fond of starting inductive loads(other motors).  They are also not easilly regulated, as about the only way to regulate their output is by changing capacitance.  They are good at syncing to an existing AC source, such as backfeeding a grid tied power system.  Also for powering something that dosn't require a regulated source such as conversion to DC to directly feed an inverter.  Now if you are powering a light in every hut in a village, it is a good cheap option.  But if you are planning on powering a modern western lifestyle with constantly varying automated loads, you are going to be sadly disappointed and probably fry some of those modern conveniences due to under/over voltage.  If this is what you are trying to power, a ST will be a plug and play 1800 RPM solution.  An induction motor will NOT...
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