O/T - 115v or 208/230v motor Q?

I'm electrically challenged and regularly let out the magic smoke, lol.

If a motor is single phase can it run on either 115v or 230v?

Will it just run at 1/2 speed?

Almost all single phase motors a constructed 'dual voltage'. This means that they can run on either of the voltages you noted with no difference in RPM or HP output. Connecting the motor for the higher voltage will mean it will draw much less (1/2) current than if wired for the lower voltage.

The end user decides which voltage to run the motor on and connects the wires in the junction box to achieve that. Every motor comes with a diagram of wire connection for each voltage.

Stuart

If it says so on the label it can. Needs to have reconfigurable windings for the different voltages. The label shows the different configurations and wire colors on the right. That one definitely can be with correct wiring.

Duh, told you I was challenged.

So connect the wires as in "low voltage" and Bob's my Uncle?

Terry Keeley said:

Duh, told you I was challenged.

So connect the wires as in "low voltage" and Bob's my Uncle?

Click to expand...

Yes..just like the diagram shows.

Stuart

just to dot the "i" -- "Low Voltage" connection should be for 115V use. I suspect motor damage might occur if motor is hooked up to 220V while being wired as "Low Voltage".

Bob is indeed your uncle from what I've heard.

Thanks guys.

I picked up this brand new Cincinnati SPB-9 blower for a song. Fan wasn't seated on the shaft propery so it rubbed a bit and of course it was 220v, lol.

Seated the fan and rewired it for 120v, man does it blow! (or suck?)

On an AC motor, voltage does not determine sped.

Just a bit more explanation.

A dual Voltage (115/230 VAC), motor will have two coils and they are wound in the same position, on top of each other, if you will. Each of these coils will be designed to be connected to 115 VAC. When the motor is configured for 115 Volt use, the two coils will be connected in parallel and each will be connected to the 115V supply.

But when it is configured for 230V use, the two coils will be connected in series. Being connected in series and also having the same number of turns and made with the same gauge wire, those coils will have the same resistance (impedance actually) and they will form a Voltage divider that is connected across the power line. Since the resistance is equal, they will divide that 230 Volts in half and each coil will "see" the 115V that it was designed for.

The inner workings of the motor will show absolutely no difference when these two types of connection are used. The magnetic fields will be identical at every instant in time. The torque will be the same. The HP will be the same. The start-up times would be the same. The amount of heat generated would be the same. In fact a sufficiently small midget with an array of small instruments who is confined to the inside of that motor, not including the connection panel or a Volt meter connected to the ends of the coils, would have very little in the way of determining which Voltage the motor was connected. The motor's operation is really exactly the same in each configuration.

Externally the 115V configuration, with the two coils in parallel, will draw twice the current as the 230V, serial connection. Thus the power, which is given by Voltage X Current will be the same in each case.

Terry Keeley said:

Duh, told you I was challenged.

So connect the wires as in "low voltage" and Bob's my Uncle?

Click to expand...

Wires yes.

These days, "Bob" might actually be your Aunt, though.

Theory aside, single-phase motors run a skosh cooler in the high-Voltage configuration if you have the choice.

Few motors ever went to Collitch, so they just do as they please.