Generator Hook up 1 phase zig zag or double delta

[mciikurzroot]

Recently it was brought up about what hook up to use when setting up a real 12 lead generator, rather to use the zig zag or Dbl Delta. In my experience i have not found a unified or common agreement among GENERATOR manufactures, i find mixed answers reccomending one of the two. So when I am confronted to make a 1 phase hook up , looking at the two diagrams, one seemed a more obvious choice than the other, but what swings it for me ? I went back and looked at what MEP did and does in the 002/003 and 802/803 sets and followed in the new 1020/30 sets. They use the DD, when you look at the two windings, it seems obvious and logical the DD balances all 6 windings and the ZZ uses 4 windings on one side and 2 on the other side, this inbalance seemed to be just not offer a well balanced equal demand on each winding, where the DD does...

I will add here, we are told to derate the expected KW output ability when using a 12 lead set, typically by 30% or so in a 1 phase application. I dont give that a lot of value, these generators are so well built with regard to temp rise, frame size and performance standards , full capacity operation might cause the actual generator to become warm, but warm is expected and accounted for, i do and would just encourage users to perodically feel the actual generator case/body and let common sense be your guide. My exception to this derating would come in a marginal or competetive low cost generator, but our military generators are not spec'd marginally.. Recall please, in the 802/803 no derating is called out or cautioned for between 1 and 3 phase operations...

Best: mac/mc

 

[Scoobyshep]

I have been using a zigzag for years on a 004 and it actually does use all 6 windings.



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[Scoobyshep]

Now that I have time to sit and explain as ZZ can be quite confusing:

In a ZZ setup All 6 windings are contributing to the load. To simplify things I am going to eliminate the parallel aspect. In the factory wye configuration using 3 windings numbered according to the NEMA standard there are 6 leads (3 windings) 1 and 4 2 and 5 3 and 6, 45and 6 are tied together to form your neutral and 1 2 or 3 to neutral is 120 volt. As the North end of the rotor magnet reaches (for lack of a better term) top dead center on winding A winding B is on its rising edge from the south pole and C is still moving south. (Hard to visualize so draw a big Y and lay a pen down on the center and rotate it, sounds silly but it seemed to help some of my former students) this gets 208 because the poles of the magnet are 180 degrees apart but the windings are only 120.

Now zig zag it, 5 gets disconnected from 6&4 and now joins 3. do the same pen trick as winding B increases winding C decreases and they average out to 120 (add in winding A which is now 180 out from the end of winding 2) 240 .

Now for load, when you load a wye wound generator, the ideal situation is to load each leg evenly example a 3000 watt load should be split up as 3 1000 watt loads on the 3 legs. At this point even though each winding is seeing 1000w the set is loaded to 3000 watt. If you did the same thing in a ZZ both legs will take 1500 watts each.



In my own (literal) backyard I have a 004 that i have setup to run a Low Zig Zag, and in the process of getting it all setup I needed to load bank (1 to prove it works, 2 to clear up some wetstacking as it was showing signs) I was able to run for several hours at 115% of rated load (15kw set running 17200 watts)


Hopefully this clears some things up and sheds some light on the subject.

 

[mciikurzroot]

Now that I have time to sit and explain as ZZ can be quite confusing:

In a ZZ setup All 6 windings are contributing to the load. To simplify things I am going to eliminate the parallel aspect. In the factory wye configuration using 3 windings numbered according to the NEMA standard there are 6 leads (3 windings) 1 and 4 2 and 5 3 and 6, 45and 6 are tied together to form your neutral and 1 2 or 3 to neutral is 120 volt. As the North end of the rotor magnet reaches (for lack of a better term) top dead center on winding A winding B is on its rising edge from the south pole and C is still moving south. (Hard to visualize so draw a big Y and lay a pen down on the center and rotate it, sounds silly but it seemed to help some of my former students) this gets 208 because the poles of the magnet are 180 degrees apart but the windings are only 120.

Now zig zag it, 5 gets disconnected from 6&4 and now joins 3. do the same pen trick as winding B increases winding C decreases and they average out to 120 (add in winding A which is now 180 out from the end of winding 2) 240 .

Now for load, when you load a wye wound generator, the ideal situation is to load each leg evenly example a 3000 watt load should be split up as 3 1000 watt loads on the 3 legs. At this point even though each winding is seeing 1000w the set is loaded to 3000 watt. If you did the same thing in a ZZ both legs will take 1500 watts each.



In my own (literal) backyard I have a 004 that i have setup to run a Low Zig Zag, and in the process of getting it all setup I needed to load bank (1 to prove it works, 2 to clear up some wetstacking as it was showing signs) I was able to run for several hours at 115% of rated load (15kw set running 17200 watts)


Hopefully this clears some things up and sheds some light on the subject.

Im sorry if i cast the impression that ONLY 4 winding were being used, I realize every winding is used [6] my effort was to show the apparent imbalance in the ZZ wherein it uses 4 winding on one side and 2 on the other side for a total of all 6 being used, I have no doubt at all it [ZZ] works, I was aiming for the obvious equal looking balance drawn from each respective WINDING Vs. the ability to support an equal or apparent load on each individual winding assuming as you have proven the overall combination can support. It was not my intent to cast the thought only 4 of the 6 winding were being used. I think we are both working from practical experience's and successful ones at that, but for me, what sealed it was how the 803/804 are used in 1 phase applications. I don't have the time in the near future to go back in and break out the individual internal hook ups and measure the current from the 2 sets of windings , 1 set of 4 and 1 set of 2 as well read the temp and try to establish a base line. I take no exception from what you have said or your own experiences. And i welcome the views and your experiences, this forum is such a good wealth of exchange and experiences, no one comes away not learning from this group..
best: mm

 

[Don+23805]

Now that I have time to sit and explain as ZZ can be quite confusing:

In a ZZ setup All 6 windings are contributing to the load. To simplify things I am going to eliminate the parallel aspect. In the factory wye configuration using 3 windings numbered according to the NEMA standard there are 6 leads (3 windings) 1 and 4 2 and 5 3 and 6, 45and 6 are tied together to form your neutral and 1 2 or 3 to neutral is 120 volt. As the North end of the rotor magnet reaches (for lack of a better term) top dead center on winding A winding B is on its rising edge from the south pole and C is still moving south. (Hard to visualize so draw a big Y and lay a pen down on the center and rotate it, sounds silly but it seemed to help some of my former students) this gets 208 because the poles of the magnet are 180 degrees apart but the windings are only 120.

Now zig zag it, 5 gets disconnected from 6&4 and now joins 3. do the same pen trick as winding B increases winding C decreases and they average out to 120 (add in winding A which is now 180 out from the end of winding 2) 240 .

Now for load, when you load a wye wound generator, the ideal situation is to load each leg evenly example a 3000 watt load should be split up as 3 1000 watt loads on the 3 legs. At this point even though each winding is seeing 1000w the set is loaded to 3000 watt. If you did the same thing in a ZZ both legs will take 1500 watts each.



In my own (literal) backyard I have a 004 that i have setup to run a Low Zig Zag, and in the process of getting it all setup I needed to load bank (1 to prove it works, 2 to clear up some wetstacking as it was showing signs) I was able to run for several hours at 115% of rated load (15kw set running 17200 watts)


Hopefully this clears some things up and sheds some light on the subject.

Just what I will be looking for! So 4,5,6 are the normal wye neutral; agreed. So you are saying take 5 off that old neutral and instead connect it to 3. Now your single phase neutral is just 4 & 6. So your two new hots are 1 & 3. What do you do with 2 ?

Don

 

[Ray70]

On the 30% derating, I don't think the 12 wire heads are expected to be derated, my impression was always that only the 10 wire heads used in the 804 and 805 need to derate by 30% if you are attempting to pick single phase off 2 of the 3 legs, since that head can't be reconfigured to true single phase.

 

[Scoobyshep]

Just what I will be looking for! So 4,5,6 are the normal wye neutral; agreed. So you are saying take 5 off that old neutral and instead connect it to 3. Now your single phase neutral is just 4 & 6. So your two new hots are 1 & 3. What do you do with 2 ?

Don

In the above example 1 is line 1 6/4 is neutral 2 is line 2. 3/5 is a winding interconnect. So 1 to 2 is 240 volt. 2 to 6/4 is 120 and 1 to 6/4 is 120.

Keep in mind this is an oversimplified explanation of how the physics work. In practical application there is a bit more to it (since its a low voltage there is a paralleled set of windings) the 2 i wired (a 004 and 005) 1 and 3 ended up being used and l2 became the unused tap.

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