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10/20/2017 1:01:18 AM
9/22/2017 12:11:25 AM
Posted: 9/21/2005 6:26:37 PM EDT
Guy & Gals,
Can someone explain the difference between "3Ø Series Delta" and "1Ø Double Delta" as it pertains to 120/240 volt electricity. Onan lists their 3Ø PTO generators as being able to provide 120/240 volt electricy under these two voltage configurations. You can read the details at www.onan.com/pdf/cmobile/a-1394.pdf, on page 3 under the section titled "Reconnectable Voltage Configurations" for 3Ø generators, in the last two columns on the right hand side of the page.

I understand the essential difference between 3Ø and 1Ø in that 3Ø actually has 3 "hot" wires to drawn from and that each of those wires is in a difference phase of its sine wave, and that the voltages are different than regular 1Ø 120/240 volt. We do not have a need for 3Ø electricity but the 3Ø units are offered in a higher kW rating.

Thanx in advance!

Link Posted: 9/21/2005 7:00:40 PM EDT
All It means , for your concerns, is that the windings of the generator can be configured for three phase or single phase. You should get a higher amp output per phase in a single phase configuration because you will have more windings per phase. But a higher total KW output if wirred for three phase.
Link Posted: 9/21/2005 9:39:49 PM EDT
Link Posted: 9/22/2005 3:58:02 AM EDT

Originally Posted By David_Hineline:
If you do not need to run 3 phase equipment I would not see any reason to overly complicate the circuitry.

If you need more KW total load then buy two smaller generators and when the load of one is exceeded the second one can be set to come online.


That's not an option for this since it's a PTO driven unit on a truck.
Link Posted: 9/24/2005 8:04:12 PM EDT
btt
Link Posted: 9/24/2005 8:31:39 PM EDT
[Last Edit: 9/25/2005 5:42:55 PM EDT by JPC]
Most of the GENERATED power in the world is 3ph,,smaller transmission lines
Single phase ,pulsates., three phase remains consitant.Also with a 3ph you can derate wire size by about 75% a way to save dinero on installation I hate pulling in 600ft of 4/0 service conductors.
1ph wire #8awag = 3ph #12awag[example only,you need to do your calcs]
Delta is just the configuration ,,there's ,delta ,,wye,,delta/wye combined,wye/delta
Link Posted: 9/24/2005 8:52:12 PM EDT
[Last Edit: 9/24/2005 8:55:02 PM EDT by Foxxz]
Most all houses only have 1-phase power at 240v. You get 240v because you have 2 hot 120v lines 180 degrees out of phase. Looka something like this:

+ 120v line-----\
|------------------|
|------------------|
+ Neutral Line---} Using the two 120v lines (one as a "neagtive and one as a "positive") you get 240v
|------------------|
|------------------|
+ 120v Line----/




This is a 3-phase wave form. 1-phase is just one of those waves isolated.
Heavy duty motors use 3 phase because it is more powerful and continuous. The peaks are closer together only being 90 degrees out of phase with the preceeding phase. Each phase has its own set of wires. Therefore, you get 3x as much power (which requires 3x more power to drive the generator).

So if you get a 3-phase power generator that can put out 20 amps it would be like having 3 single phase generators that can each put out 20 amps.

I won't get into the delta and wye configurations. But basically with 3 phase power you can cross connect the different phases to get voltages like 480 and 720v but at lower amperages.

-Foxxz
Link Posted: 9/25/2005 3:43:39 AM EDT
[Last Edit: 9/25/2005 7:30:05 AM EDT by txgp17]

Originally Posted By Foxxz:
I won't get into the delta and wye configurations.
-Foxxz

Foxxz, that's an excellent explanation, thanz a million, but an explanation of the delta and wye configurations is really what I'm looking for, can you elaborate more on that? If one of those configurations can provide 40kW of 1Ø 120/240, then we could get 5kW more of capacity than we would if we went with the single phase 35kW model.

Right now, the plan calls for 18kW of halogen scene lights, so we're looking to have every ounce of reserve capacity that we can. In truth, the straight 1Ø 120/240 35kW unit will likely power everything we would want, but I'd like to plan the truck to take advantage of every "maximum" capacity that we can.
Thanx in advance,
-txgp17
Link Posted: 9/25/2005 10:23:38 AM EDT
[Last Edit: 9/25/2005 10:23:59 AM EDT by KBaker]
Here's a connection diagram showing a single-phase double delta.

Here's one showing what I think they're calling 3-phase series delta 120/240

That help?
Link Posted: 9/25/2005 10:50:03 AM EDT
If most or all of your loads are 120volt the three phase Detla offers little or nothing extra over a single phase for you to use. The Delta config taps the center between two of the 6 windings.
Link Posted: 9/25/2005 10:57:00 AM EDT
Link Posted: 9/25/2005 5:40:52 PM EDT
[Last Edit: 9/25/2005 6:50:54 PM EDT by JPC]
To answer your question about the differences of Delta vs Wye connections,,
In a Wye connection LINE voltage is higher then the phase voltage,,line current [amps]and phase current are the same,,Delta is the opposite,,line voltage=phase voltage,,line current is higher the phase current
# reasons why 3ph is better,yes you can have 3ph 120/240
1-hp rating ,kilovolt rating of 3ph transformers are about 150% greater then 1ph
2-in a balanced 3ph system conductor size is approximatly 75% the size of a 1ph 2wire system
3-power is more consistent,,it never falls to 0 like a 1ph

yes "most home " services are 1ph,,just like most commercial are 3ph
transmission lines are 3ph converted to 1 ph at transformer before entering home service
Link Posted: 9/25/2005 6:12:20 PM EDT

The peaks are closer together only being 90 degrees out of phase with the preceding phase.

Actually it's 120 degrees.

The biggest pain in the neck is getting each of the three legs balanced. Maybe new generators aren't as picky about that as the old ones, but all of the 3-phase generators I've used produced terrible power unless each phase used reasonably close to the same power. Also, we had several generators quit after only a few hundred hours caused by either the 120 vibration or the extra heat created by having one phase loaded much more than the other two.

Balancing would be easy to do with the lights assuming you normally keep the same ones on. You just wire 1/3 of the lights to each phase. If you turn certain blocks of lights on and leave others off, then you could end-up unbalanced if you weren't carefule. If newer generators are better at this, then feel free to correct me. Some of the ones I worked on were built 70+ years ago.z
Link Posted: 9/25/2005 7:00:02 PM EDT

Actually it's 120 degrees.


Oops! I goofed! You're right!

-Foxxz
Link Posted: 9/26/2005 1:25:26 AM EDT

Balancing would be easy to do with the lights assuming you normally keep the same ones on. You just wire 1/3 of the lights to each phase.


It is a delta. you would have to have 220/240 volt lights to be able to balance the load. A delta config is not the best choice if most of your loads are 120.
Link Posted: 9/26/2005 4:44:00 AM EDT

Originally Posted By j3_:
It is a delta. you would have to have 220/240 volt lights to be able to balance the load. A delta config is not the best choice if most of your loads are 120.

All of the planned 18kW of lights will be 240 volt, although not always the same one will turned on. It would consist of 12 1,500 watt halogen lights, 6 mounted on a pneumatic light tower, 2 mounted to each side of the body, and one on each front corner.
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