Electrical Question for home made Air cleaner

[Bill Swanson]

So I have bit the bullet and found a 230 volt motor and squirrel cage fan out of an old air handler.

I am going to build an air cleaner for the shop based on the plans in one of the wood Mags.

The label on the motor says it is a 230 volt motor, so I have to run a circuit for it.

My question is on the wiring of the motor. Out of the motor there is a red, blue, black and purple wire the going to the connector on the blower frame. There is also two brown leads that go to the capacitor mounted on the frame.

Anyone have any ideas on where to start to wire this? In that there are four wires coming out of the motor, might it be a variable speed motor?

Any help would be much appreciated.

Thanks

[Rod Sheridan]

Hi Bill, you do indeed have a 3 speed motor.

The easiest way to determine what the wires are for, aside from using the nameplate information is as follows;

1) measure the resistance from wire to wire and write it down

2) take the highest resistance reading and look at the colours, one of these will be the common wire.

3) measure from one of the possible common wires to the other two. If you have the common wire, both readings will be high. If one is high, and one low, try the other wire that may been the common.

I predict that you'll find this;

1) Purple to black is high speed ( high resistance)

2) Purple to Blue is medium speed (higher resistance)

3) Purple to Red is low speed (even higher resistance)

Once you've found out what your colour code is, check what the motor current is rated at (nameplate). Once your filter box is constructed and all the filters are in place, put the motor in low speed mode and measure the current.

If the current is equal to the nameplate rating, that's as fast as you can run the motor.

If the current is lower than the nameplate rating, go to the next speed and repeat the process to determine if you can run at that speed.

Once you've tried out the three speeds, you can determine if you can run your fan as a single, two, or three speed air cleaner.

Regards, Rod.

The

[Bill Swanson]

I did use a Ohm meter and it is as you predicted.

It is a three speed.

Does anyone have any ideas on where to get a 230 switch to do all three speeds for this project? What might be the proper terminology for this device?

Thanks

Bill

[Tom Veatch]

You only need to switch one leg of the supply, so a SP3T (Single Pole, Three Throw) would work. So, I'd look for a SP3T rotary switch with an "OFF-ON-ON-ON" configuration with the proper amperage rating.



http://www.google.com/products?q=SP3...&hl=en&show=dd

[Rod Sheridan]

Actually Tom, you do need a 240 volt switch, as the switch will see the entire line to line voltage when you open it.

I would wait to see what the motor current is with the filter restrictions before purchasing a switch. You may only be able to you use one or two speeds.

Regards, Rod

[Tom Veatch]

Actually Tom, you do need a 240 volt switch, as the switch will see the entire line to line voltage when you open it....

Darn, you're right. Forgot about the starting transient condition. Sorry about that.

[Bill Swanson]

Thanks for the info.

I got it up and running, on high the start current is 2.4 amps and the run is 1.1.

I think I will look for the switch to be able to slow it down when necessary.

For right now it is cleaning away when needed.

Bill

[Randy Denby]

Bill, that switch will be fairly expensive if purchased at a electronic/electric parts supply . A cheaper alternative ....I'd look for a Window A/C unit rotary switch at a HVAC wholesaler. Most have at least 3 switching positions and can handle higher current draws as they usually switch the compressor on as well.