120 to 240

[Jeff Bratt]

The universal motors in the biggest routers actually develop 1½ HP or less. An efficient induction motor running on a 120V 15A circuit could be 1¾ HP. And the newest, very high efficiency motors should be just a little more. And don't get me started on shop vacs - 6 or 7 "peak HP" - yeah, right.

[Jeff Bratt]

Am I getting close to the 1,000,000th post yet . . . .?

Near the bottom of the main SMC page you can see the total number of posts - we still have a few more to go....

[Chris Padilla]

On a dual voltage motor, the voltage across the field coils is always exactly the same, whether you're running the motor on "high" voltage or "low" voltage. It's only external things that affect the motor, especially the ability of the circuit feeding the motor to maintain the rated voltage. That's why many people find that running a motor on "high" voltage improves the performance - the circuit only has to supply half the amps so there's less chance of a voltage drop.

But inside the motor, it's exactly the same on either voltage.

Mike

Well, the voltage drop is across the wiring in the wall. The resistance of that wiring is fixed so as the current changes, so does the voltage drop. If the current is cut in half, so follows that the voltage drop is also cut in half but it is still there.

Running at 240 V only gains you something in the wiring in the wall. At less current being drawn, there will be less voltage drop over the resistance of the wire in the wall and therefore less power loss and less heating-up of the wire in the wall.

In my mind, on motors that can run on either/or, that is all that one will gain going with the higher voltage. For me, that is enough and so I try to wire all dual coiled motors at 240 V if it's convenient for my setup.