Author Topic: ST head wiring  (Read 8614 times)

adhall

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Re: ST head wiring
« Reply #15 on: July 08, 2007, 05:06:07 PM »
rpg52:

I would try swapping U2 with U6 and see what you get. It sounds to me like you have good reason to believe the wires were incorrectly labelled.

By this I mean to disconnect U5 from U6 and then connect U5 to U2 instead. Wires U1 and U6 should have 240 VAC between them.

Best regards,
Andy Hall
JKSon 6/1, 5 kW ST Head, 1992 Dodge RAM Cummins 5.9L Turbodiesel, 2001 VW TDI 1.9L Turbodiesel, 2006 Jeep CRD Turbodiesel, Yanmar FX22D Diesel Tractor

rpg52

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Re: ST head wiring
« Reply #16 on: July 08, 2007, 06:05:13 PM »
Mystery solved!!

Thanks, ronmar, Doug and adhall, I connected U5 to (the mis-labeled) U2, checked the voltage across U1 and (the mis-labeled) U6 and got 240v AC!   ;D  ;D  ;D

Back in Business - thanks again everbody.  I still don't exactly understand the how/why of this, but, all is well.

Ray
PS Listeroid 6/1, 5 kW ST, Detroit Diesel 3-71, Belsaw sawmill, 12 kW ST head, '71 GMC 3/4 T, '79 GMC 1T, '59 IH T-340

adhall

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Re: ST head wiring
« Reply #17 on: July 08, 2007, 11:43:40 PM »
rpg52:

What was happening was that the phase was reversed on one winding. This caused the voltage on that winding to cancel out the voltage on the other winding. At any given point in time, the instantaneous voltage on one winding would be equal and opposite to the voltage on the other. When you put windings in series, you get the algebraic sum of the voltages of the individual windings. This is why you could still measure 120 VAC across each individual winding (i.e. between U1 - U5 and U2 - U6), but virtually zero across the extreme ends of the two windings in series (i.e. between U1 - U6).

I can't explain the problem you described in your first post, though. It is possible to connect the two windings in parallel and get 120 VAC on a two wire connection. Do you suppose you had it set up that way at first?

Best regards,
Andy Hall

JKSon 6/1, 5 kW ST Head, 1992 Dodge RAM Cummins 5.9L Turbodiesel, 2001 VW TDI 1.9L Turbodiesel, 2006 Jeep CRD Turbodiesel, Yanmar FX22D Diesel Tractor

rpg52

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Re: ST head wiring
« Reply #18 on: July 09, 2007, 12:51:40 AM »
Yes, I had one hot (red going out) and another hot (black going out), and neutral (white) tied to what I thought was U5+6.  With it attached to my little subpanel box, each leg was hot, but I couldn't get 240v out of it, because, as you say, each leg canceled out the other.

For now, I only have one circuit with 240v, the plug for my arc welder.  The other 120v circuit always worked fine.  Only when I tried to use the 240v would they cancel each other out and the arc welder would never work. 

I think, (based on my faulty memory) that the original doghouse was connected correctly, only the (one or more??)  leads coming out of the windings were labeled incorrectly.  Had I not replaced the doghouse, everything would have worked fine and I would never have known about the mislabeling.  Oh well.   ;)
Ray

PS - after re-reading my first post, I think what I meant to say was I was getting 120v from either U1 or U2 to neutral.  When I measured across U1 to U2, I got almost nothing.
« Last Edit: July 09, 2007, 12:54:41 AM by rpg52 »
PS Listeroid 6/1, 5 kW ST, Detroit Diesel 3-71, Belsaw sawmill, 12 kW ST head, '71 GMC 3/4 T, '79 GMC 1T, '59 IH T-340