Is Pzb Bugged Here, Or Am I?

I had a weird encounter with PZB tonight on the 10th mission of DRA, the first S1 route in the Dresden direction. The first two stops went fine, but I got an unexpected emergency brake application leaving the third one, and it just did not feel right.

I have a pretty solid understanding of PZB, and play almost entirely with PZB and Sifa on -- things get too boring without it. But I'm not sure what happened here, and I'm hoping someone can either explain a part of the system I missed or confirm that this is bugged behavior.

I put a video segment of one run on Youtube since it's often easier to see these things for yourself. I'll describe and link key timecodes.

0:57 - about 930m from Neusörnewitz I pass a distant signal with a yellow aspect for a red 1.2km ahead. I acknowledge and the 1000Hz light comes on.
1:29 - about 260m from the stop and 480m from the signal the 1000Hz light goes out, leaving me just the flashing 85.
1:58 - I come to a stop at the station and get the 70/85 flashing of restricted mode.
2:52 - I leave the station and release restricted mode, get a solid 85.
3:25 - I pass the signal, which switched to yellow while I was at the station. I acknowledge the yellow, but immediately go into emergency braking mode.

In this particular attempt in the video I tried pressing Override as I passed the signal, to see if that did anything. It didn't. But prior to that I had the same behavior without Override.

The next thing I tried (which I also recorded, but won't bother uploading) was to proceed as in that video, but crawl along at 20km/h until I was past the yellow, in case I was in some sort of invisible restricted mode. That worked -- I was able to acknowledge the signal and the 1000Hz light came on as per normal.

(I just realized, watching that second video back to confirm the behavior, that on that attempt I never bothered releasing from the restricted mode I entered at the stop -- I stayed in it all the way to the signal. I don't think that is supposed to matter here though.)

At any rate: this feels distinctly off to me, and I suspect it's bugged behavior of some sort, but I'm compelled to understand every system I touch, so I'm wondering if maybe there's some aspect of PZB I'm overlooking that would cause this?

Thanks for any help folks can give!

 

That was your mistake: you released PZB in the face of a non-green signal. If the next signal isn't green, you have to leave PZB monitoring on or the 500-Hz magnet will initiate a Zwansbremsung, which is what happened to you.

You have to leave monitoring in place until either it turns itself off, or you are facing a green (or 500 m with no signal)
It's also probably the case that you stopped at the station with the red 500 light on: 500-hz monitoring holds you to 25, not 45.

 

When you left the station at 2:52 you could clearly see that the next signal was YELLOW and not green, but you pressed the RELEASE button anyway to get out of the restricted mode. This is not allowed, and is what triggered the emergency brake application when you reached the yellow signal.

What happened is the following:

1. You pressed the "release" button.
2. PZB said: fine, I take your word that you have seen a clear signal and I will release you but I will remember you should be in restricted mode until you had run 1250m.
3. You passed over the 1000Hz magnet next to the yellow signal at 49 Km/h and acknowledged it.
4. PZB said: 1000Hz magnet acknowledged. This guy has not run the 1250m and should still be in restricted mode, so I will apply the restricted mode limits immediately. He is running at 49Km/h when the restricted mode limit is 45 Km/h. Triggering emergency brake application now!

 

Ahh, that made it click for me, and it makes perfect sense when laid out that way. Before I posted I looked over the documentation on PZB in the manual for Zusi 3 (the most comprehensive description of it I've ever seen in one place) and it says that:

"If the driver releases the train from the first speed control before the second speed control has been activated, the first braking curve that is still running in the background will immediately become active again, in which case the target speed will immediately be 85/70/55 km/h. The basic principle of the PZB90 is that: All speed limiters will be activated, and the most critical case will always apply. It is only the latter that will be shown in the indicator unit."

I thought that I might be resuming a previous curve when I hit that yellow, but even if I were at just a little above 45km/h it felt like it would be fine. But I guess the second sentence can be read as referring to what you say: the system "thought" I was in restricted mode, so as soon as I hit the yellow the most critical case kicked in, and I needed to be going under 45. That would also be why my attempt where I deliberately kept low speed succeeded, too.

OK, so the bug was in me, after all. This is why I like to ask questions. Thank you, and thank you for your answer too, solicitr.

 

What solicitr states was my first thought, however there is no 500Hz magnet being triggered here. Inkar's explanation makes the most sense to me. Releasing yourself from restrictive monitoring when you can see a non-green signal is not a good idea, but it shouldn't trigger penalty braking automatically when acknowledging a 1000Hz magnet. What ultimately tripped you was your speed being higher than what is allowed under restricted monitoring.

Cheers

 

Yeah, I was slightly puzzled by solicitr's response, given that there was no 500Hz magnet active here. I thought perhaps I'd done something which might hide the light, though, and was in the middle of replying asking for a bit more explanation when I got the notification about Inkar's reply and went "aha!"

Thanks to all three of y'all.