Electrical Engineering - Induction Motors: 110V vs 220V

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Induction Motors: 110V vs 220V

– Colonel –

2008-01-27, 5:25 pm

I have a question for the engineers/scientists out there.

I have a table saw with a 1.5hp induction motor (TEFC) that can be
wired for either 110V or 220V. It's currently wired for 110V
single-phase AC.

I remember my father used to rewire his table saw's motor, changing it
to 220V. He said he didn't think doing so gave it any more power; it
just gave it more "snap" in getting started quickly.

Here's my question: In an application where an induction motor was
pushed close to its power limit (i..e., 1.5 horsepower) in a
continuous-duty application, or even an intermittent-load situation,
wouldn't wiring it to run on 220V be better than 110V if you were
concerned about thermal overload?

I don't entirely understand how an induction motor works, but it seems
that if you double the voltage, you're going to cut the heat-producing
amperage in half in the windings, and thus the motor will run "cooler"
at the higher voltage.

Am I anywhere close to correct here?

Are there other/any advantages to wiring a table saw motor to run on
220V as opposed to 110V?

Thanks for any feedback.

Andrew Gabriel

2008-01-27, 5:25 pm

In article <2008012716404616807-nobody@verizonnet>,
=?UTF-8?B?4oCTIENvbG9uZWwg4oCT?= <nobody@verizon.net> writes:
> I have a question for the engineers/scientists out there.
>
> I have a table saw with a 1.5hp induction motor (TEFC) that can be
> wired for either 110V or 220V. It's currently wired for 110V
> single-phase AC.
>
> I remember my father used to rewire his table saw's motor, changing it
> to 220V. He said he didn't think doing so gave it any more power; it
> just gave it more "snap" in getting started quickly.
>
> Here's my question: In an application where an induction motor was
> pushed close to its power limit (i..e., 1.5 horsepower) in a
> continuous-duty application, or even an intermittent-load situation,
> wouldn't wiring it to run on 220V be better than 110V if you were
> concerned about thermal overload?
>
> I don't entirely understand how an induction motor works, but it seems
> that if you double the voltage, you're going to cut the heat-producing
> amperage in half in the windings, and thus the motor will run "cooler"
> at the higher voltage.
>
> Am I anywhere close to correct here?

No. Most likely it has two windings which can be connected
in parallel for 110V or series for 220V. It makes no
difference to the motor.

> Are there other/any advantages to wiring a table saw motor to run on
> 220V as opposed to 110V?

Yes, 220V will only draw half the current, which equates
to only a quarter of the resistive losses in the supply
wiring. This will mean the motor can draw a larger surge
without losing so much of it in the supply wiring losses.
Also, on a US 120-0-120V supply, you are balancing the
load across both legs, rather than dragging it all from
just one side, which might result in less noticable sags
and spikes for other appliances (lighting in particular).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

– Colonel –

2008-01-28, 9:25 am

On 2008-01-27 17:49:14 -0500, andrew@cucumber.demon.co.uk (Andrew
Gabriel) said:

> In article <2008012716404616807-nobody@verizonnet>,
> =?UTF-8?B?4oCTIENvbG9uZWwg4oCT?= <nobody@verizon.net> writes:
>
> No. Most likely it has two windings which can be connected
> in parallel for 110V or series for 220V. It makes no
> difference to the motor.
>
>
> Yes, 220V will only draw half the current, which equates
> to only a quarter of the resistive losses in the supply
> wiring. This will mean the motor can draw a larger surge
> without losing so much of it in the supply wiring losses.
> Also, on a US 120-0-120V supply, you are balancing the
> load across both legs, rather than dragging it all from
> just one side, which might result in less noticable sags
> and spikes for other appliances (lighting in particular).

OK, thank you, Andrew, for the info.

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