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Author Topic: 12 lead 3 phase to single phase TR2 zig zag or double delta  (Read 13064 times)

TR210KW3ph

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12 lead 3 phase to single phase TR2 zig zag or double delta
« on: January 30, 2012, 08:53:42 PM »
Back in 2007 I got a used TR2 10KW 12 lead Lima marathon 3 phase generator from dieselgman, rebuilt the top end and rewired it to zig zag for 120/240 single phase.
Last week had a 66 hour run from the Ice storm, in Western Washington.  It wet stacked towards the end, not loaded enough, so have been doing some searches and found the double delta schematic for single phase. Would that be any better than zig zag for loading.
Thanks Larry Harter

dieselgman

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Re: 12 lead 3 phase to single phase TR2 zig zag or double delta
« Reply #1 on: January 31, 2012, 01:52:46 AM »
Yes, Double Delta should be a more balanced loading for your genhead.
However, that is not a strict requirement to get your engine properly loaded.
Those Marathons are very robust and hard to overload anyway... If you used zig-zag and overloaded the single winding pair then it is possible to heat up the head in an unbalanced manner. Better to use the Delta configuration if in doubt, and if it fits your needs.

Gary
DES
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TR210KW3ph

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Re: 12 lead 3 phase to single phase TR2 zig zag or double delta
« Reply #2 on: January 31, 2012, 07:05:12 PM »
Thanks Gary, Please refresh my memory, if my generator was rated at 10KW 3 phase, how much less would it be on double delta 120/240 single phase, how many amps per leg?

Larry Harter

dieselgman

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Re: 12 lead 3 phase to single phase TR2 zig zag or double delta
« Reply #3 on: February 01, 2012, 04:23:45 AM »
Larry,

Your Marathon 3-phase head, reconnected single-phase low-voltage Delta (double delta) will be rated at 2/3 of its original 3-phase rating. [Only two output leads and only 120vac.] This is because one 'side' will have two winding pairs and the other only a single pair. Technically a bit wasteful of efficiency and of copper when not using a 3-phase balanced loading scheme.

Now the tricky part in dealing with Marathon ratings is that they were individually (or in small batches) configured per customer requirements and can have a lot of variances even within the same product family ... this takes a careful read of the original data plate and an interpretation of what setup the stamped rating was originally based upon. The good thing, all the old Marathon stuff was built with ample overload capacity. It is just pretty hard to damage one of these due to overloading.

dieselgman
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Thob

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Re: 12 lead 3 phase to single phase TR2 zig zag or double delta
« Reply #4 on: February 01, 2012, 02:50:08 PM »
Larry,

I think your original question is about loading the engine enough to prevent wet stacking - I don't think changing from zig-zig to double delta is going to change the engine loading any noticeable amount.  You need more load on the generator - that would mean running electric heaters or charging batteries or heating water or some other activity to put more load on the engine.  None of these are very efficient; the only way I know to do that is get a smaller generator.

I'm not familiar with the TR2 - air cooled or water cooled?  If it's water cooled, make sure the thermostat is a high enough temperature model to keep the engine running hot when lightly loaded.  If air cooled, you may need baffles to reduce the cooling when lightly loaded.  Do you have a way to monitor engine temperature?
Witte 98RC Gas burner - Kubota D600 w/ST7.5KW head.
I'm not afraid to take anything apart.
I am sometimes afraid I'm not going to get it back together.

dieselgman

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Re: 12 lead 3 phase to single phase TR2 zig zag or double delta
« Reply #5 on: February 01, 2012, 06:02:02 PM »
TR2 is air-cooled and we never use any cooling-air restriction, always match engine size to the predominant load if possible, or simply add loads as necessary.

The observation about engine loading being unrelated to genhead wiring is absolutely correct. The two questions are unrelated. The most efficient use of the LIMA 12-lead is in 3-phase mode and with a balanced load (across all 3 phases) of at least 75% of engine capacity. Delta is somewhat preferable to Zig-Zag unless you also need single-phase 240. I hope that this is clear and focused enough to be helpful.

Thanks Thob! Sometimes additional ways of describing things helps to clarify.

dieselgman

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TR210KW3ph

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Re: 12 lead 3 phase to single phase TR2 zig zag or double delta
« Reply #6 on: February 02, 2012, 08:10:05 PM »
So how may amps can I pull on single phase zig zag 120/240 V, the gen head plate says 30 amps at 3 phase, is that 10 amps per phase x 3 = 30 or 30 per phase?

Thanks Larry Harter

Thob

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Re: 12 lead 3 phase to single phase TR2 zig zag or double delta
« Reply #7 on: February 02, 2012, 11:24:55 PM »
It should be 30 per phase.  If you wire it up as a 3-phase y, you can have 30A per each 120V phase, 3600 watts per phase, or 10,800 watts total (10.8KW).  If you wire it up zig-zig or double delta for single phase, you should get 30A per phase, 3600 watts per phase, or 7200 watts total.

The current is normally limited by the wire size, and by how much heat (how high a temperature) the wire's insulation can withstand.  So the current that can be drawn from an individual winding is the same whether the generator is wired for single phase or three phase.  Total power is limited by how much current you can safely draw, and how much power the engine can provide.  Unfortunately, I don't think you can create a generator (at least cost effectively) that can generate full power at both single and three phase.
Witte 98RC Gas burner - Kubota D600 w/ST7.5KW head.
I'm not afraid to take anything apart.
I am sometimes afraid I'm not going to get it back together.

dieselgman

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Re: 12 lead 3 phase to single phase TR2 zig zag or double delta
« Reply #8 on: February 03, 2012, 01:23:36 AM »
Right, 30 amps per phase - and of course, limited by horsepower input.

dieselgman
Ford Powerstroke, Caterpillar 3304, Cummins M11, Too many Listers to count...