Elvas Tower: Idea: Diesel-Electric Manual Transistioning - Elvas Tower

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Idea: Diesel-Electric Manual Transistioning For First-Generation diesel fanatics...

#11 User is offline   disc 

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Posted 03 January 2017 - 12:23 PM

Oh i see! Transistioning means field weakening, electric counter current, etc. But parallel series switching is used on DC locomotives. Old AC locomotives (and some diesels too) have field weakening shunt switching, sometimes manual, sometimes automatic.

Here is an example:

Hungarian V-43 AC electric locomotive with series-wound DC motors (SCR AC-DC conversion) with field weakening shunt switch, and tapped transformer notch switching.
First raise the pantograph, then close circuit breaker, switch on cooling, turn the throttle controller to N (neutral), then move to + to switch to higher notch. As you can see each notch has a max speed where the current, and back EMF countercurrent reach their equilibrium state. By using field weakening shunt(field divert switch on video), the back EMF can be lowered, so the equilibrium happens at higher rpm and speed.
The british Class 86/87 works the same way, just it has automatic control for field weakening.
As the V-43 above is built first by french license (in 1960s) probably there are some french locomotives that work the same way. Also the russian M62 diesel-electric locomotive which is used in Hungary and Poland too, has the same field weakening method, but that's automatic.

Throttle controller notches:
-- = instant off for traction, and run-down tranformer tap notches
0 = run-down tap notches
- = one tap notch down
N = neutral
+ = one tap notch up
++ = run-up tap notches

#12 User is offline   Tyler Bundy 

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Posted 03 January 2017 - 12:30 PM

We had a discussion about transition at trainsim.com recently as part of the GP16 thread. From the first-hand accounts of engineers, transition is a noticeable event on many diesel-electric locomotives and can be quite rough to the ride and train handling.

Generally, early North American first-generation diesels had manual transition through roughly 1950. I didn't find a firm answer to that question, though Operator Manuals at rr-fallenflags.org showed the automation of transition happening in the Alco RS2 and EMD F3 era. I didn't thoroughly investigate BLH or Fairbanks-Morse enough to understand their designs. Many switch engines didn't need transition because they didn't reach high speeds.

After automatic transition became common on new locomotives starting in the 1950s, the new locomotives still featured a manual transition lever. This was in place to control older locomotives with manual transition that might be trailing units in MU. When all MU units were automatic, each unit would automatically transition itself without input from the engineer.

An EMD GP9 has four stages of transition: Series-Parallel, Series-Parallel Shunt, Parallel, Parallel Shunt. From my experience, the switch to Parallel was the most noticeable, around 20-25mph. The speed value is variable between models and manufacturers and also varies with gear-ratio.

I don't recall ever noticing the introduction of the field shunt. It must be a smoother transition than Series-Parallel to Parallel. The Series-Parallel to Parallel transition actually re-wires the traction motors, so a break in power is inevitable with this system.

For EMD, transition characteristics changed in 1966 with the introduction of the AC alternator instead of a DC generator, and again in the early 1980's with the GP50/SD50 series. Starting with the 50-series, transition takes place inside the alternator, with the traction motors wired in permanent Parallel. From what I read, AC locomotives don't need transition and have different operating characteristics from DC locomotives.

I'm interested to see what the OR team does to re-create this event. Could a load-regulator recovery time be instituted to mimic General Electric locomotives' throttle response characteristics? Alco and EMD seemed to have pretty stable throttle response, but old GE's were infamous for dropping their load with throttle adjustment, including the slow build up that GE was also infamous for. I think automatic transition has a similar effect on locomotive performance, dropping the load for a short time while transition occurs, but is based upon speed rather than throttle movement.


#13 User is offline   Hamza97 

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Posted 03 January 2017 - 07:34 PM

Implementing transitioning will also require sound triggers, to trigger filed divert sound at particular speed/throttle...

#14 User is offline   Traindude 

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Posted 20 August 2017 - 04:40 PM

Sorry to bump this thread, but I want everyone to know that I have submitted my transitioning idea to the Trello Board and so far, it only got one vote (me). So here's the link to vote for it if you want to see it implemented: https://trello.com/c...-electric-locos

#15 User is online   darwins 

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Posted 18 May 2018 - 09:32 PM

Well you just gained one more vote, now that I understand what 'transitioning' means!

There seem to be quite a few variations as far as I can see.

With older a.c. electrics there is the tap changing first described.

With diesel electrics then although you might move say from full field to weak field the changes in power within that were mostly controlled by changing the rpm of the diesel engine.

Then for older d.c. electrics I would like to see as part of this. A controller with perhaps four of five positions - shunt, series, series/parallel, parallel. Within each position a series of relays open and close contacts to step up the power until you reach maximum for that section. So stepping up power - much like the tap changer - but without manually being able to select each notch. Sound wise there would need to be the clicking up or down through the relay contacts. Hopefully some one knows more than I to be able to give more detail.

#16 User is offline   R H Steele 

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Posted 18 May 2018 - 10:15 PM

just found this thread, as I was reading a manual tonight, and found this...

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