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Home > Archive > Electrical Engineering > May 2006 > DC motor
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| Hello, I have recently built DC motor which suppose to run at Minimum
5000 RPM under 10 Foot-LBS torque when 27 VDC applied per
specification. But my motor run at 4800 RPM.
I need to know what factors could cause the RPM to drop?
Thanks,
Mike
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"Mike" <hfakhar@yahoo.com> wrote in message
news:1147374989.022098.286310@i40g2000cwc.googlegroups.com...
> Hello, I have recently built DC motor which suppose to run at Minimum
> 5000 RPM under 10 Foot-LBS torque when 27 VDC applied per
> specification. But my motor run at 4800 RPM.
> I need to know what factors could cause the RPM to drop?
>
> Thanks,
> Mike
Is your motor running a load at the stated RPM?
A freewheeling motor, i.e. no load can turn faster.
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| Salmon Egg 2006-05-11, 9:21 pm |
| On 5/11/06 12:16 PM, in article
1147374989.022098.286310@i40g2000cwc.googlegroups.com, "Mike"
<hfakhar@yahoo.com> wrote:
> Hello, I have recently built DC motor which suppose to run at Minimum
> 5000 RPM under 10 Foot-LBS torque when 27 VDC applied per
> specification. But my motor run at 4800 RPM.
> I need to know what factors could cause the RPM to drop?
>
> Thanks,
> Mike
>
You have not supplied much detailed information necessary to get a good
answer. Your best bet is to hire an electrician experienced with a dc motor
or a PE EE. One guess is that your field current is too high.
Measure current in the armature. That should give a decent idea of what the
torque is.
Bill
-- Ferme le Bush
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| operator jay 2006-05-11, 10:21 pm |
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"Mike" <hfakhar@yahoo.com> wrote in message
news:1147374989.022098.286310@i40g2000cwc.googlegroups.com...
> Hello, I have recently built DC motor which suppose to run at Minimum
> 5000 RPM under 10 Foot-LBS torque when 27 VDC applied per
> specification. But my motor run at 4800 RPM.
> I need to know what factors could cause the RPM to drop?
>
> Thanks,
> Mike
>
Do you know your mechanical load is actually 10 foot-pounds @ 5000rpm?
Do you know there is actually 27Vdc at the machine terminals _when running_?
Is the voltage from a clean source?
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