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#57888 - 10/22/05 08:16 PM Septic System Controls & Pumps
Tiger Offline
Member
Registered: 05/04/05
Posts: 706
Loc: Crystal Lake, IL USA
I'm installing the wiring for a septic system on a commercial complex and am curious about some things on the print.

There are six pumps and two blowers in this system. Why would this system use three phase when all the pumps and motors are single-phase?

The main disconnect is showing three-phase and single-phase, but with only one neutral. Is this correct?

Thanks
Dave
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#57889 - 10/22/05 10:44 PM Re: Septic System Controls & Pumps
mxslick Offline
Member
Registered: 10/24/04
Posts: 803
Loc: Atomic City, ID USA
Tiger:

Two possibilities come to mind:

One, the mfg. makes a system with larger pumps which require 3 phase power, but uses the same controller with smaller single phase systems.

Two, it is an attempt to provide a balanced load to the system's supply at least as far as the pumps are concerned.

As for the disconnect, perhaps the motors are all 208-240v and can operate phase-to-phase and the control system itself requires 120 volts. (Thus the single neutral.) Again, seems to be a move to avoid multiple inventory on disconnects.

Do you have a link to the mfg.?
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#57890 - 10/23/05 02:04 AM Re: Septic System Controls & Pumps
Wolfgang Offline
Member
Registered: 09/25/05
Posts: 153
Loc: the very West of Germany
Just looking at your question from another continent:

The idea of a 3-phase system is that with a balanced load on the 3 phases current on the (always) one and only neutral is going to zero.

3 phase (120°) is sort of an actual standard service in some parts of Europe even for the smallest apartment.

But if there is no three phase consumer in the installation you will be free to switch to single phase or balance it between two 180° single phases or whatever you want.

So where does the guy come from who did the wiring scheme?
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#57891 - 10/23/05 04:50 AM Re: Septic System Controls & Pumps
Trumpy Offline


Member
Registered: 07/05/02
Posts: 8211
Loc: SI,New Zealand
Hi Dave,
It would seem that the designer wants the pumps and blowers connected in a Star (Wye) topography, hence the Neutral.
The Neutral in this configuration will only carry the Out of Balance current.
Which if done like this will be in the order of a few Amperes, if that.
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#57892 - 10/23/05 05:32 AM Re: Septic System Controls & Pumps
Tiger Offline
Member
Registered: 05/04/05
Posts: 706
Loc: Crystal Lake, IL USA
The link for this manufacturer is www.aquarobicinternational.com

The unit I'm wiring is the one with two fiberglass tanks and a constructed wetland.

The motors are single-phase 240 volt, and the controls are 120 volt.

Dave
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#57893 - 10/23/05 07:30 AM Re: Septic System Controls & Pumps
harold endean Offline
Member
Registered: 02/16/02
Posts: 2233
Loc: Boonton, NJ
This is just my 2 cents but when you do your work or your bid make sure about your wiring methods. In some applications you might need a Class I Div. 1 wiring.
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#57894 - 10/23/05 07:56 AM Re: Septic System Controls & Pumps
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9039
Loc: Estero,Fl,usa
Good point Caper. We needed seal offs on the raceways feeding the lift pumps down in the honey pot.
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#57895 - 10/23/05 08:10 AM Re: Septic System Controls & Pumps
Tiger Offline
Member
Registered: 05/04/05
Posts: 706
Loc: Crystal Lake, IL USA
Good point. I think I'm looking at three options here.

The manufacturer provides a pvc box inside the tanks with terminal strips. The pumps have power cords with plugs. If I can get manufacturer's instructions to cut the plugs and use their pvc box that may be a good option,

Explosionproof outlets, or

run the cords outside the tanks to std. exterior outlets.

Thanks
Dave
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#57896 - 10/23/05 12:06 PM Re: Septic System Controls & Pumps
mxslick Offline
Member
Registered: 10/24/04
Posts: 803
Loc: Atomic City, ID USA
Found this on the bottom of the linked page:

Quote:
The Maxi-Plants equipment package comes completely assembled and wired. Field assembly consists of installing the air diffusers system, fiberglass manway(s) and inter-connecting electrical wires to the control panel.

Standard electrical requirements for the Maxi-Plant TM series:

From 5,000 to 15,000 gallons per day:

1 phase, 60 Hz., 230 volt, 2 hot wires plus a neutral and a ground wire,


From 15,000 to 85,000 gallons per day:

3 phase, 230/460 volt, 60 Hz., 3 hot wires plus a neutral and a ground.

The timer, alarm and control system on all units are always 115 volts single phase powered.


So it seems that all units in the 15k-85k gals. cap. range will use the same std. panel, and perhaps if the unit Dave's installing is near the bottom end of that range the pumps will be single phase, but the input power requirement will be three phase as Trumpy noted.

I would guess that the larger unit's pumps would be three phase.
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#57897 - 10/23/05 03:55 PM Re: Septic System Controls & Pumps
Wolfgang Offline
Member
Registered: 09/25/05
Posts: 153
Loc: the very West of Germany
May I just simply ask (still looking from Europe) how one provides
3 phase, 230/460 volt, 60 Hz., 3 hot wires plus a neutral and a ground.
with additional 115V for the alarming?

A small link to a wiring scheme of the transformer would be sufficient to imagine what strange things you're doing over there.

Thanks Wolfgang
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