[Coolhand101]

As we know, the ammeter values and gauges in OR only correspond to the actual tractive effort applied. This is of course incorrect.

In MSTS, there was actually current implemented shown as amps, as well as tractive effort. This could be followed using the extended HUD under MSTSBin. The ammeter parameter in the engine section was for this very purpose.

Could actual ammeter current be implemented in OR ? Also adding an ammeter table, where you could manually input the amps vs power and speed? This could also be the way forward to overloading the motors if the amps get to high, where on electric and diesel locos that have a red ammeter section, the motors could trip.

Another possible way in having ammeter current/table that if wheelspin is encountered, the amps could fall very quickly and once wheelspin has finish, the amps could be too high for the actual road speed leading to an overload of the traction motors.

As for wheelspin, the actual motor sounds are not tied into the actual wheel rotation, so even if the wheels are spinning at 100 mph and train speed is 10mph, the traction motor sounds are tied into the train speed and not the wheel speed. Can anything be done about this? I believe steamers have this implemented, where if the wheels slip, the chuffing noises gets faster?

Any thoughts on this?

Thanks

[ErickC]

I think it's a great idea, especially if we get sound variables to go with it. Engine exhaust volume ought to be directly correlated to engine load, and the ammeter would be a perfect variable for this purpose. We could then transpose the frequency by engine speed, and the volume by load, and eliminate the need for awkward transition clips. I could finally get a roots-blown 567 or 645 to sound right! Totally on board with linking motor sounds to wheel rotation. It would be cool if we could specify a differential variable for wheel slip sounds as well.

[R H Steele]

I like this. I don't know enough to spot any drawbacks, any anticipated? --- and Ericks notion that the sound would be more realistic is very intriguing. http://www.elvastower.com/forums/public/style_emoticons/default/cool3.gif

[Lindsayts]

Its very difficult to properly simulate the motor current in a series DC motor as one of the input variables is the motor current itself. it MAY be possible to use an iterative routine, I have though not tried that as iterative routines are usually quite time consuming and one does NOT have to much spare time.
You can though work the motor current out by working backwards, you take the tractive effort and use a look up table based on the traction motors characteristics (EMD's D77 Current to TE graphs certainly are availible).
Working out the current when the motor slips will be a challenge though, this could probably be "faked" from what happens in real life though.

Lindsay

[Coolhand101]

 Lindsayts, on 27 October 2017 - 10:22 PM, said:

Its very difficult to properly simulate the motor current in a series DC motor as one of the input variables is the motor current itself.
Lindsay

The EMUS that i have running in OR have the series DC motor. They notch up to 400A in series, 800A in parallel and 1000A in weak-field. I cannot simulate this in OR with the ammeter as it stands. I have used the ORTS traction characteristics table to simulate this current via the tractive effort for the see-saw effect of the resistors being knocked out with speed.

In the real world, once the notching/resistance is finished, all series DC motors should follow the same current curve. The current on DC motors falls very quickly and then follows a nice smooth decline of the current with speed.

I don't pretend to know all the in's and out's on the DC motor characteristics but maybe a start is to have current implemented as it stands in MSTS, which just corresponds to the percentage of the power handle and the ammeter setting in the ENG section, then declines with speed!

Thanks

[hroch]

Would it be possible to use this interpolator? And create at least two tables for traction current and dynamic current.

[Lindsayts]

 Coolhand101, on 27 October 2017 - 10:54 PM, said:

The EMUS that i have running in OR have the series DC motor. They notch up to 400A in series, 800A in parallel and 1000A in weak-field. I cannot simulate this in OR with the ammeter as it stands. I have used the ORTS traction characteristics table to simulate this current via the tractive effort for the see-saw effect of the resistors being knocked out with speed.

In the real world, once the notching/resistance is finished, all series DC motors should follow the same current curve. The current on DC motors falls very quickly and then follows a nice smooth decline of the current with speed.

I don't pretend to know all the in's and out's on the DC motor characteristics but maybe a start is to have current implemented as it stands in MSTS, which just corresponds to the percentage of the power handle and the ammeter setting in the ENG section, then declines with speed!

Thanks

Simplifying the motor current problem........

Hope this makes sense :(.

Motor current is proportional to main Altenator/generator voltage, traction motor back emf and inversely proportional to total motor/altenator circuit resistance. In turn traction motor back emf is proportional to armature speed and motor current (ie with a series field the motor current also runs through the field).
Hence to wok out motor current you have to work out the traction motor back EMF which is a function of the motor current it self. I believe the ONLY way one can solve this is to have a guess at the motor current, work out the motors back EMF and see if this makes the equation work. If as is likely it does not work out, you modify the guess and have another go. You keep doing this until one gets a balance. Such routines can take a good deal of time and one may have many such locos in the simulation.

Under normal operation (ie not slipping) on can easily work out the motor current by working backwards from the notch position, loco speed and tractive effort and for this one can (and I do) use an interpolator to get the motor current from the tractive effort, this will not work for the slipping condition.

Lindsay