| Author |
Why do 3-phase motors operate at a lower voltage at 50Hz then at 60Hz?
|
|
| MetalGeek65@gmail.com 2006-06-29, 9:26 am |
| For example, a small motor I use has the following on the nameplate:
60Hz - 230/460Vac - 1.4/0.70A
50Hz - 200/400Vac - 1.5/0.75A
The output power is the same as the current increases correspondingly,
but why does the voltage change?
| |
| Charles Perry 2006-06-29, 9:26 am |
|
<MetalGeek65@gmail.com> wrote in message
news:1151509026.056526.280830@x69g2000cwx.googlegroups.com...
> For example, a small motor I use has the following on the nameplate:
>
> 60Hz - 230/460Vac - 1.4/0.70A
> 50Hz - 200/400Vac - 1.5/0.75A
>
> The output power is the same as the current increases correspondingly,
> but why does the voltage change?
>
The output power is NOT the same. The motor's horsepower rating will be
lower at the lower frequency and voltage.
Why the lower votlage? Because that this the standard European voltage. The
voltage does not "change", they are giving you current information at the
voltage that the motor will be connected to.
Charles Perry P.E.
| |
|
| hi every body
with the magnetiic devices, they are designed for a rated flux, so you
should have the ration volt per hertz constant
Salmon Egg wrote:
> On 6/28/06 8:37 AM, in article
> 1151509026.056526.280830@x69g2000cwx.googlegroups.com,
> "MetalGeek65@gmail.com" <MetalGeek65@gmail.com> wrote:
>
> Lower voltage is necessary because you do not want the magnetic components
> to saturate. Lower frequency means lower reactance. Even so, it looks like
> this particular rating allows a bit more applied voltage than mere scaling
> would indicate. That is why the current drawn increases. Finer detail of the
> trade-offs eludes me.
>
> Bill
> -- Ferme le Bush
| |
| Red Face 2006-06-30, 9:25 am |
|
"roma" <brmamor@gmail.com> wrote in message
news:1151595070.106429.94130@x69g2000cwx.googlegroups.com...
> hi every body
>
> with the magnetiic devices, they are designed for a rated flux, so you
> should have the ration volt per hertz constant
>
>
> Salmon Egg wrote:
>
| |
| mark@ems-fife.co.uk 2006-06-30, 9:25 am |
|
MetalGeek65@gmail.com wrote:
> For example, a small motor I use has the following on the nameplate:
>
> 60Hz - 230/460Vac - 1.4/0.70A
> 50Hz - 200/400Vac - 1.5/0.75A
>
> The output power is the same as the current increases correspondingly,
> but why does the voltage change?
Charles Perry has it right.The nameplate is giving you the current
requirements at different voltages.The output power is easily
calculated by Ohms law.
Mark
www.ems-fife.co.uk
| |
| Don Kelly 2006-06-30, 9:25 am |
| <mark@ems-fife.co.uk> wrote in message
news:1151624987.696500.89670@d56g2000cwd.googlegroups.com...
>
> MetalGeek65@gmail.com wrote:
>
> Charles Perry has it right.The nameplate is giving you the current
> requirements at different voltages.The output power is easily
> calculated by Ohms law.
> Mark
> www.ems-fife.co.uk
--------------------
Ohms Law will not give the output power. Ohms law doesn't work for motors.-
even DC motors.
In addition, Ohm's Law is not a power relationship and the power factor is
not unity.
--
Don Kelly dhky@shawcross.ca
remove the X to answer
----------------------------
>
|
|
|
|