[chenanli]

My two buddies and I are a bunch of mech. Engineer students trying to build a HVAC laboratory unit for our senior project class and we don't even know if it's possible to connect 1phase components with 3 phase components. Say for example a 3 phase humidifier and a 1 phase fan connected to one power strip. (Someone in the heating & ventalation section told us to connect them separately but I probably would also like to know why go 1 phase instead of 3 phase components or vice versa for our HVAC.)

We were thinking of just sticking to 1 phase components just for the fact that I don't think our school has the outlet to do 3 phase, but just wanted to know what others think before we start anything and buying parts that won't help/work at all...

Any tips would help a lot! I just hope this doesn't sound confusing to anyone...

[smoothy]

You can't power 3 phase equipmet directly from a single phase power source.

You NEED to know what you have available for power before you commit to anything. That's the easy part.

[tkrussell]

You can get single phase from a 3 phase system.

Smoothy is correct, you need to know what type of power you do have available.

Time to bring in a buddy form the EE course.

[chenanli]

Thanks. We decided to go with one phase since we only got the regular house hold outlets available to us. I really wished we had a EE buddy in our team since the beginning of this project...

[edtech87]

3 phase and 1 phase are supplied at different voltages from the power company just for starters. Industrial power is usually 3 phase because they typically consume large amounts of power when the equipment is large and 3 phase is supplied at (3) 120 degree phases to help motor armatures achieve more torque. An example is air compressors for industrial use are always 3 phase because the starting torque must overcome inertia, static friction and the work of compressing the cylinder. If you must "mix" equipment to achieve better economical use of available resources, you can get "cheater" boxes that will produce an extra phase to help get the humidifier compressor started by connecting one of the motor phases to one side of a capacitor, the other side of the capacitor to another phase hot wire and the other motor phase to the supply. This is not something you should try on your own, but you can use 240V supply to run a 3 phase 208V are available on eBay for specific motor amp ratings but realize that you need to be very careful as all of this can cost you your life if you do not do it correctly - remember if anyone asks, you did not here it from me. Consult an electrician or one of your electrical engineering teachers for more local advise before connecting any power.

[tkrussell]

Ever hear of 120/208 volt 3 phase 4 wire system, widely used in light commercial, schools, light industrial, even large residential buildings?

For starters, try understanding that power utility plants only furnish three phase.

So where does the single phase come from?