[pschlik]

I did some experimenting with the ORTSContinuousForceTimeFactor parameter since I always had it configured but never noticed it having any effect, in the process of investigating I noticed some behaviors I wasn't expecting but which might be intended. In short, I was only expecting the continuous force time factor to cause the tractive effort to reduce if the tractive effort was sustained above the continuous rating for extended periods of time. Instead, I found that tractive effort was being reduced at any power level, even below the continuous rating.

For a controlled test, I set up a custom dummy locomotive with a max continuous force of 10,000 pounds, max force of 20,000 pounds, 10,000 horsepower so that horsepower wouldn't be the limiting factor, and a continuous force time factor of 60 seconds to speed up the process. If I floored it and let the locomotive reach the full 20,000 pounds of tractive effort, the tractive effort relatively quickly dies off toward 10,000 pounds. If I then reduce the throttle to half, the force drops to 5,000 pounds and gradually increases. So far, this makes sense-exceeding the continuous rating caused the motors to warm up, limiting their power, and backing off on the throttle lets the motors cool off, raising their power.

However, if I keep the throttle at 50%, the tractive effort only returns to around 6,600 pounds at steady-state, instead of the full 10,000 pounds I'd expect from 50% throttle. If I restart and only use 50% throttle from the start, despite staying within the 10,000-pound continuous rating the tractive effort dies off from 10,000 pounds to that 6,600-pound mark from before. Why would the motors overheat so much when I'm staying below the continuous effort?

From reading the manual, I was given the impression that this feature was intended to only have a noticeable effect when the continuous rating was exceeded, which is what I was hoping for as this would be a great way to simulate the automated systems modern locomotives have to reduce traction in response to thermal overload. But that is clearly not the case as it still has a significant (albeit, only a ~35% reduction rather than a ~50% reduction) effect even when remaining below the continuous rating. So implementing this feature just reduces the efficiency of the locomotive over time, regardless of the throttle setting. Luckily, the source code also explained why I never noticed this having any effect: if MaxForce and MaxContinuousForce are set to the same number, a quirk in the calculation will mean no reduction in tractive effort happens. I just so happened to set MaxForce and MaxContinuousForce to the same number for an unrelated reason.


What I don't know is if the manual misled me, and it is actually intended that using the continuous force time factor will cause the tractive effort to reduce at all throttle settings, or if this is some unintended consequence of the way the feature was implemented.

[Coolhand101]

Hi

I tested this out a few years ago.

The only thing that has changed is the time limit. On early OR versions, there was no minimum time limit. Now, I believe the lower limited is set at 1800 seconds by default.

If my trainsets have 100kN for maximum force, I set the CTE to 90kN(10%) and the ORTSContinuousForceTimeFactor set at 3600 seconds. So my overall traction performance falls by 10% over a one hour period when power is applied. However, I havent notice this fall off increase when power is not applied.

Thanks

[pschlik]

There is no minimum time, 1800 just so happens to be the default time. Thank goodness for that, the ability to set the time to 60 seconds made it so much more obvious what was happening.

Using this feature to put a flat % penalty on performance after a long time operating is interesting, but I can't tell if that's the intended use case, and it's definitely not what I was hoping to use it for. I'm hoping someone who was around when this was originally implemented can shed more light on the purpose of the feature.

[Coolhand101]

pschlik, on 09 May 2023 - 07:06 PM, said:

There is no minimum time, 1800 just so happens to be the default time. Thank goodness for that, the ability to set the time to 60 seconds made it so much more obvious what was happening.

Using this feature to put a flat % penalty on performance after a long time operating is interesting, but I can't tell if that's the intended use case, and it's definitely not what I was hoping to use it for. I'm hoping someone who was around when this was originally implemented can shed more light on the purpose of the feature.

Hi

From memory, I believe this feature is correct as performance does degrade over time but there was confusion about what you also questioned. This feature better suits D.C than A.C traction, that was the conclusion!.

I thought the minimum time was hard coded to 1800 seconds in later OR version, as I could have sworn that when I set this to 60 seconds, nothing happen in that time period!

So as you stated, setting the MF and CTE to the same level, will not cause any performance drop, so that hasn't changed.

Most traction motor performances give a one hour rating. This is why I set mine to 3600 seconds for a good few years now.

Thanks