60 Hertz Tolerance ??? ( Descriptive )

R

Randy Gross

Guest
Following is a less candid approach to this question:

I'm using a 1/10HP, 2800RPM, 12vdc, continuous duty motor to run a
generator. I designed the rotor with a dual purpose: to mount the eight
poles and, being a 9" diameter x 7/16" thick disk, act as a flywheel with
the idea of relieving some of the burden placed on the motor. Properly
balanced and cruising at 900RPM, I expect good performance.

My problem lies in capturing the needed motor speed. I've considered using
a belt drive with a 3 to 1 speed reduction but, that leaves 100RPM rampant.
That will change the frequency to 66.7 hertz. I'm not sure that I can
accurately reduce the speed mechanically, this is a new area for me.

I want to keep this genny as close to fail-safe as I can, as few components
as possible while achieving the desired output.

an Inquiring Mind
Randy Gross

----------------------------------------------------------
<') >< Homebuilt Arc Welder, Saturable Core Reactor and more...>< ('>
http://www.gomedia.ca/~aaawelder/
Chance favors the prepared mind whose hands do the work!
 
In sci.electronics.design Randy Gross <rgwg99@acsplus.com> wrote:
Following is a less candid approach to this question:

I'm using a 1/10HP, 2800RPM, 12vdc, continuous duty motor to run a
generator. I designed the rotor with a dual purpose: to mount the eight
poles and, being a 9" diameter x 7/16" thick disk, act as a flywheel with
the idea of relieving some of the burden placed on the motor. Properly
balanced and cruising at 900RPM, I expect good performance.

My problem lies in capturing the needed motor speed. I've considered using
a belt drive with a 3 to 1 speed reduction but, that leaves 100RPM rampant.
That will change the frequency to 66.7 hertz. I'm not sure that I can
accurately reduce the speed mechanically, this is a new area for me.
Click to expand...
What's wrong with simply using a sightly larger/smaller pulley?
Say 3.33:1<
 
"Randy Gross" <rgwg99@acsplus.com> wrote in message
news:01c3b1f6$f3f1ff20$2e2525d8@defalut...
Simply is what I am looking for. I looked for a source here in town but,
no
luck. I typed in pulley at google and it gave me sweaters (go figure). If
you could simply point me to a source, I would be thankful.
Click to expand...
Where's "in town" for you? Is there a Grainger outlet handy? (If not, they
do mail order, I believe.) They'll certainly have what you need, though
some of their stuff is pricey.
 
I read in sci.electronics.design that Randy Gross <rgwg99@acsplus.com>
wrote (in <01c3b1f6$f3f1ff20$2e2525d8@defalut>) about '60 Hertz
Tolerance ??? ( Descriptive )', on Sun, 23 Nov 2003:
I typed in pulley at google and it gave me sweaters (go
figure).
Click to expand...
Maybe you typed 'pully' in error. It's a twee abbreviation for
'pullover', which is a sort of sweater.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!
 
Ian Stirling <root@mauve.demon.co.uk> wrote in article
<Pd7wb.12099$lm1.88983@wards.force9.net>...
: In sci.electronics.design Randy Gross <rgwg99@acsplus.com> wrote:
: > Following is a less candid approach to this question:

<Snip>

I'm not sure that I can
: > accurately reduce the speed mechanically, this is a new area for me.
: >
:
: What's wrong with simply using a sightly larger/smaller pulley?
: Say 3.33:1<
:
Simply is what I am looking for. I looked for a source here in town but, no
luck. I typed in pulley at google and it gave me sweaters (go figure). If
you could simply point me to a source, I would be thankful.

Randy
 
Randy Gross wrote:

Simply is what I am looking for. I looked for a source here in town but, no
luck. I typed in pulley at google and it gave me sweaters (go figure). If
you could simply point me to a source, I would be thankful.
Click to expand...
Over here I think the keyword is 'belts'. Now, belts and pulleys have
the same problem. Maybe V-belts?


Thomas
 
"In Town" for me is Indianapolis, IN and the economy here is a mystery
indeed. It seems all (almost) of the machine shops (auto industry related)
are shutting down or are about to. They are not just downsizing to
skeleton, they are in the grave, locked and assets auctioned. The question
here is: Why is everyone jumping ship?

Walter Harley <walterh@cafewalterNOSPAM.com> wrote in article
<bpr2ch$u35$0@216.39.172.65>...
: "Randy Gross" <rgwg99@acsplus.com> wrote in message
: news:01c3b1f6$f3f1ff20$2e2525d8@defalut...
: > Simply is what I am looking for. I looked for a source here in town
but,
: no
: > luck. I typed in pulley at google and it gave me sweaters (go figure).
If
: > you could simply point me to a source, I would be thankful.
:
: Where's "in town" for you? Is there a Grainger outlet handy? (If not,
they
: do mail order, I believe.) They'll certainly have what you need, though
: some of their stuff is pricey.
:
:
:
 
"Randy Gross" <rgwg99@acsplus.com> wrote in message news:<01c3b1e5$3576a160$2e2525d8@defalut>...
Following is a less candid approach to this question:

I'm using a 1/10HP, 2800RPM, 12vdc, continuous duty motor to run a
generator. I designed the rotor with a dual purpose: to mount the eight
poles and, being a 9" diameter x 7/16" thick disk, act as a flywheel with
the idea of relieving some of the burden placed on the motor. Properly
balanced and cruising at 900RPM, I expect good performance.

My problem lies in capturing the needed motor speed. I've considered using
a belt drive with a 3 to 1 speed reduction but, that leaves 100RPM rampant.
That will change the frequency to 66.7 hertz. I'm not sure that I can
accurately reduce the speed mechanically, this is a new area for me.

I want to keep this genny as close to fail-safe as I can, as few components
as possible while achieving the desired output.

an Inquiring Mind
Randy Gross

----------------------------------------------------------
') >< Homebuilt Arc Welder, Saturable Core Reactor and more...>< ('
http://www.gomedia.ca/~aaawelder/
Chance favors the prepared mind whose hands do the work!
Click to expand...
Why dont you just use an inverter?
 
Hi Randy,

The exact speed of the DC motor will not normally be 2800 RPM. In a DC
motor, the motor speed is close to being directly proportional to the
voltage. So, even under the best of conditions your motor's speed will be
no more accurate then your 12 volt DC source. The motor's speed will also
vary with load. Even if you get a pulley that will give 60 Hz at 2800 RPM
your speed will vary significantly with your source and load. Also note
that motor ratings are nominal and in the case of a DC motor, you may not be
at exactly 2800 RPM at exactly 12 Volts and a 1/10 Hp load.

Having a flywheel is a good idea as it will help smooth out sudden changes
in load, but you will still need some type of speed regulation system to
stay close to 60 Hz.

My advice would be to use the 3:1 pulley. Then sense speed on the
alternator shaft using a tach generator, optical encoder, or whatever and
have the speed regulator drop the motor speed as needed to hold 900 RPM for
your alternator. The easiest way would be by having the speed regulator
adjust the source voltage (I'm guessing that your DC motor is a PM type).

I know that you said in your post that you want to keep it simple, but
you'll need some type of speed regulator if you want an accurate alternator
frequency. If you want an idea of where to start do a google search on "DC
motor control" and "PID control".

If you want more help both the group and I would need a bit more info on
what you are trying to do, the frequency accuracy you need, what you are
using for a 12 volt source (battery, lab supply, etc.), what type of DC
motor you are using, and what type of load your alternator is going to see.

Hope this helps,
Big John

--->>> Remove the nospam to reply to my email address <<<---


Randy Gross wrote in message <01c3b1e5$3576a160$2e2525d8@defalut>...
Following is a less candid approach to this question:

I'm using a 1/10HP, 2800RPM, 12vdc, continuous duty motor to run a
generator. I designed the rotor with a dual purpose: to mount the eight
poles and, being a 9" diameter x 7/16" thick disk, act as a flywheel with
the idea of relieving some of the burden placed on the motor. Properly
balanced and cruising at 900RPM, I expect good performance.

My problem lies in capturing the needed motor speed. I've considered using
a belt drive with a 3 to 1 speed reduction but, that leaves 100RPM rampant.
That will change the frequency to 66.7 hertz. I'm not sure that I can
accurately reduce the speed mechanically, this is a new area for me.

I want to keep this genny as close to fail-safe as I can, as few components
as possible while achieving the desired output.

an Inquiring Mind
Randy Gross

----------------------------------------------------------
') >< Homebuilt Arc Welder, Saturable Core Reactor and more...>< ('
http://www.gomedia.ca/~aaawelder/
Chance favors the prepared mind whose hands do the work!
Click to expand...
 
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