MEP 804A RETAPPING

[rangerxp1000]

Has anyone tried retaping a 804 A unit from 3 phase to single phase,

 

[Scoobyshep]

Has anyone tried retaping a 804 A unit from 3 phase to single phase,

IIRC the head on the 804 is only 10 lead (T10, T11, and T12 are bonded internally) So without a head rewind you cant.

 

[Ray70]

Hundreds of discussions about the subject here on the forum, but as Scoobyshep stated it's pretty much impossible with the 10 wire gen head.

 

[Scoobyshep]

If you really really want to you can set the unit to 416 volt and use transformers. But that might be a touch excessive

 

[Guyfang]

I wish we could put this old wives tale to bed. Its not possible.

 

[jamawieb]

Yes Ive done it. Ive discussed it in the past. Its very simple. On my next conversion I will take pictures. Ive switched over around 20 804 and 805a's.

 

[Ray70]

Do you have a link to where you previously discussed your conversions?

 

[jamawieb]

Do you have a link to where you previously discussed your conversions?

Let me see if I can find it. It wasn't a thread I started. The idea came from SmokeStak where an individual talked about a Bar Diamond connection. Worked on the theory with some other guys and it worked. The only set back we had was the VR. The original VR reads off all 3 legs to generate power. With Kurt Klopp's VR development, it was a game changer because his VR on reads off of 1 leg. So with the conversion, you have to put in Kurts VR, the remaining conversion is completed on the reconnection board. Its actually easier to do than the older 004 and 005 models. I have logged several thousand hours on 804s so the conversion is very dependable.

 

[2Pbfeet]

Let me see if I can find it. It wasn't a thread I started. The idea came from SmokeStak where an individual talked about a Bar Diamond connection. Worked on the theory with some other guys and it worked. The only set back we had was the VR. The original VR reads off all 3 legs to generate power. With Kurt Klopp's VR development, it was a game changer because his VR on reads off of 1 leg. So with the conversion, you have to put in Kurts VR, the remaining conversion is completed on the reconnection board. Its actually easier to do than the older 004 and 005 models. I have logged several thousand hours on 804s so the conversion is very dependable.

Are the threads by WA Ross? E.g.

Generator Conversion

I brought a 3 phase generator cheaply thinking it would suit me better than a single. However I have found that three phase equipment for domestic use is prohibitive and I would like to convert the machine to single phase: a] Is this Possible? b] If possible how would I proceed?

www.eng-tips.com

Bar Diamond or Collins Connection for 10 Lead 1 Phase 120/240

One W.A. "Bill" Ross on the eng-tips forum seems to have invented this connection. I have never found it in any book or publication. However I have used it when a customer wanted 120/240 1 phase out of a 10 lead machine with T10/T0 all bonded together. It works great and what is even greater...

www.smokstak.com

He seems very confident of his views, and they seem supported by diagrams that don't look crazy to me, but I am not an electrical engineer. He does point out the 1/3 loss in KVA capacity.

All the best,

2Pbfeet

 

[jamawieb]

Are the threads by WA Ross? E.g.

Generator Conversion

I brought a 3 phase generator cheaply thinking it would suit me better than a single. However I have found that three phase equipment for domestic use is prohibitive and I would like to convert the machine to single phase: a] Is this Possible? b] If possible how would I proceed?

www.eng-tips.com

Bar Diamond or Collins Connection for 10 Lead 1 Phase 120/240

One W.A. "Bill" Ross on the eng-tips forum seems to have invented this connection. I have never found it in any book or publication. However I have used it when a customer wanted 120/240 1 phase out of a 10 lead machine with T10/T0 all bonded together. It works great and what is even greater...

www.smokstak.com

He seems very confident of his views, and they seem supported by diagrams that don't look crazy to me, but I am not an electrical engineer. He does point out the 1/3 loss in KVA capacity.

All the best,

2Pbfeet

That is one of the articles. I shared the conversion with Peter who owns Innovahightech because he was very confident that it could NOT be done. He contacted electrical engineers with Marthon and explained the conversion, to his surprise they confirmed the ability with my drawings. Rated output of the generator is still 15kw on the 804 and 30kw on the 805. But anything over that trips the overload. Usually on the 804 I can push them until 19-20kw before overload happens.

 

[2Pbfeet]

That is one of the articles. I shared the conversion with Peter who owns Innovahightech because he was very confident that it could NOT be done. He contacted electrical engineers with Marthon and explained the conversion, to his surprise they confirmed the ability with my drawings. Rated output of the generator is still 15kw on the 804 and 30kw on the 805. But anything over that trips the overload. Usually on the 804 I can push them until 19-20kw before overload happens.

Thanks for the deep due diligence on your and Peter's (@peapvp) part! It is nice to know that on the 804/805 sets that there is no loss in capacity.

All the best,

2PbFeet

 

[Guyfang]

Good news!

 

[peapvp]

That is one of the articles. I shared the conversion with Peter who owns Innovahightech because he was very confident that it could NOT be done. He contacted electrical engineers with Marthon and explained the conversion, to his surprise they confirmed the ability with my drawings. Rated output of the generator is still 15kw on the 804 and 30kw on the 805. But anything over that trips the overload. Usually on the 804 I can push them until 19-20kw before overload happens.

@jamawieb
I am getting old, when did I have this conversation with you and Marathon(?)
I can’t remember this conversation and just checked my email archives and my steelsoldiers pm

 

[Ray70]

What am I missing here?? Reading the articles ( 2nd one in particular ) it sounds like he's saying you can rewire the 10 lead generator into a "reversed" dogleg output, but then he goes on to say the output will be reduced by 1/3 and the voltage will be 208 not 240.
What's the difference between that modification and just running your single phase loads off 2 of the original 3 phases?
Does this modification give you less output current, at 208V BUT balance the 3 legs?
( This is why I'm more of a mechanic, not an electrician.... )

 

[jamawieb]

What am I missing here?? Reading the articles ( 2nd one in particular ) it sounds like he's saying you can rewire the 10 lead generator into a "reversed" dogleg output, but then he goes on to say the output will be reduced by 1/3 and the voltage will be 208 not 240.
What's the difference between that modification and just running your single phase loads off 2 of the original 3 phases?
Does this modification give you less output current, at 208V BUT balance the 3 legs?
( This is why I'm more of a mechanic, not an electrician.... )

Ray,
It does not reduce voltage by 1/3. Ive completed the conversion on over 50 804 and 805a's. You will get 120/240v out of the set. On the 804 you will get 16kw all day long. It will surge to 20kw. But after 10 minutes on anything over 16kw it will trip the overload.
Jimmy

 

[peapvp]

What am I missing here?? Reading the articles ( 2nd one in particular ) it sounds like he's saying you can rewire the 10 lead generator into a "reversed" dogleg output, but then he goes on to say the output will be reduced by 1/3 and the voltage will be 208 not 240.
What's the difference between that modification and just running your single phase loads off 2 of the original 3 phases?
Does this modification give you less output current, at 208V BUT balance the 3 legs?
( This is why I'm more of a mechanic, not an electrician.... )

Ray, hope you’re doing well.
There is two ends to these conversions, like a sausage which has two ends and you don’t want one open….

1. the first question which has to be clarified is, whether the genhead was constructed in such way that a zig zag or dogleg will give you a phase shift of 180 degrees in single phase 240 connection between L1 and L2 or not.
A standard 3 phase genhead is constructed in such way, meaning the coil arrangement in the armature, that there is a 120 degree phase shift between each phase
Some off these heads can be reconfigured with their leads to match the voltages but they will not do the required phase shift of 180 degrees.

The now famous YouTube videos of our esteemed member shows him demonstrating the 180 degree phase shift between the two phases with his oscilloscope.
I am not sure on how exactly this was accomplished and of what he was actually showing us in his video, but he might be correct.

2. Each coil in a 3 phase generator head is wound with a specific wire gauge which will determine the maximum current each coil can produce and is determined by current draw from any one phase to neutral ( 120V).
The voltage is determined by the amount of turns each coil has.
A three phase head has 3 pairs of coils, one pair for each leg.
Each pair can be connected in series to produce 416V or in parallel for 208V which will then double the current

let’s say we have a 15KW rating with a power factor of 1 ( ideal generator ) as example.
Then when we apply ohms law and use power, we can see that we get a maximum of 72 Amps @ 208V
Now we divide the 72 Amps by 3 and we get 24 Amps per phase in parallel;
208V x 24A = 4992 VA = 4.992 KVA or KW

this means each individual coil is rated for 2.5 KW and yield 5 KW in parallel or in series because of the higher voltage 416V x 12A = 4992 VA

on the xx2 and xx3 gensets the coils are rated for the highest current in single phase 120V configuration

for a xx4 this would be 41.66 Amps x 120V = 4999.2 KVA


so in the end you will loose the power from one coil pair whenever you are doing a conversion or when you connect only to two legs on a 3 phase configured genset.

I used a power factor of 1 rather then working in the actual power factor of 0.8 PF for demonstration purposes to make it easier to be understood for all the readers who do not poses a phd in electrical engineering.


The currents with PF 0.8 are
120V 52Amps per phase
208V 26Amps between two phases
416V 13Amps between two phases

 

[Scoobyshep]

The phase shift in a low zigzag works because of the addition and subtraction of the 3rd leg tapped to leg 2. (One rises as the other falls averaging two 120volt over 2 legs)

The head is arranged where the phases are 120 apart but when leg 2 is extended it ends up 180 out. Simple way (but crude) is to draw out the windings in wye. Lay your pen over the drawing and spin it over the neutral. Tip is north clip is south each leg is 120 out. Do the same with the zigzag. You'll see they are 180 out now.

As someone who has done this to a 004 and 005 I can say the o scope readings are accurate.

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