mstrlucky74
Senior Member
- Location
- NJ
Motor Feed
- Thread starter mstrlucky74
- Start date
- Status
the way I understand it: This is a three phase load if being fed from 3P 20A. You will need 3 hot's + G.
ptonsparky
Tom
- Occupation
- EC - retired
Why do you think you need a neutral to three phase motors?
mstrlucky74
Senior Member
- Location
- NJ
idk? could you explain why not, thanks.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Because the motors need 3 phase power, not single phase. 3 phase is 3 hots, 2 hots and a neutral is still single phase. 3 phase motors don't use the neutral for anything, no reason to run it and in fact there would be nothing to connect it to at the motor.
Now, I have another issue with that drawing as shown, but then again we have no information on what it is that you are feeding. That circuit as depicted does not address how those motors are to be protected from Over Load and as a general rule, 2HP 200V motors rarely have internal OL protection. It's not unheard of, but it's a detail that must be confirmed before proceeding IMHO.
Last edited:
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
If for some unknown obscure reason you have a motor whose windings are going to be wired in a wye configuration, with a common center point, there is still no reason to connect a neutral wire to the wye point to get the motor to work properly.
And in fact if the line to neutral voltage mismatch among the three source phases is high enough, the motor will draw very unequal winding currents with the wye point connected, but more balanced currents with the wye point floating.
Whether the source is delta or wye does not have any direct correlation with how the motor is designed to be wired.
And in fact if the line to neutral voltage mismatch among the three source phases is high enough, the motor will draw very unequal winding currents with the wye point connected, but more balanced currents with the wye point floating.
Whether the source is delta or wye does not have any direct correlation with how the motor is designed to be wired.
- Occupation
- Licensed Electrician
What do you mean by unknown obscure reason? I agree there is no reason to bring a neutral to a three phase motor but motors are internally wired in a wye all the time.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Phil Corso
Senior Member
- Location
- Boca Raton, Fl, USA
- Occupation
- Licensed Electrician
Oh. I usually don't miss those. Do better next time.
- Status