[DirtyRam]

Weter, on 20 July 2021 - 09:52 AM, said:

Excuse me, but not motors, but the current in their coils.
See posts updated above. I tried to say more correct there.

Yes, trying not to be technical, it all occurs at the same time within about 5 to 10 secs. depending on the equipment.

[Weter]

In DB mode, motor's circuit is isolated from generator, so no problem, all the current they generate is directed to resistors and partially to fan(s), blowing on the latter.
Some schemes also based on their self-exaltation, so that-s the third destination of DB current.

[DirtyRam]

I should clarify, its not that the motors actually reverse. The current does to create the resistance to slow the rotation of the motors. This creates a very large amount of heat, so blower motors are needed to scavenge the heat up through the top of the unit.

[Weter]

Almost so, see post 28 update.

[Weter]

Every high load will heat the motor's iron, thanking the losses in it, whether it would be accelerating or decelerating of heavy train
The video was shown to me, where we can see, that at high notches of DB, the engine is automatically set to run 3 or 4, for giving more power to traction motors cooling fans, as the heating intensivity of them increases, while their exaltation itself doesn't demand more, then idle/run1 rpm setting.

[Laci1959]

I think if the braking is started when you see the stop indicator of the stop signal, the 10 second delay should not be a problem. Whether this type is dependent is another matter.
The sign is at the beginning of the general braking distance and is already visible from about 300-400 meters. This is the minimum distance technical specification in Hungary.

[Weter]

For electric locomotives that's more rapid changing. Trams, metro MUs.
The circuits was switched by the same controller at both modes.
Also, in case of diesel locomotive, DB is more likely used in most for speed regulation, rather than for stopping.
As for Soviet Diesel engines, (as far as the bet was done to electrification of lines with steep grades, for regenerative braking to become available, or, at least, more heavy trains could be hauled), I don't remember any DB systems, developed to series manufacturing grade. Mostly it was a kind of experimental option, mounted on some units, or used in minor batches of modified engines. I didn't seen any instruction, how to use that brakes. And can add here, that it's controls might be in form of notchless levers or in form of multistate selectors of defined speed. The locomotives, that planned to manufacturing after 1990 was prototypes, so there is not so much info. Else, I heared, that almost all that DB equipment was dismantled or left out of function, as it wasn't finished to acceptable condition of working.

That's why I wonder about that mysterious "B" notch of DB handle: does it exist, what it for and is there any latch on it for mechanic delay of engagement?
At video, I've mentioned, it seemed, the engineer have to lift or pull handle for abvancing it further.
@engineersteve
Thank you for leaving professional comment, but what if you would say here, what is wrong with dynamic brakes behavior in ORTS for we to try correct that, or to ask dews to enchance the code for its correct working. As I can remember, we told about incorrect sound side of dynamic brake control handling, but what about wrong functions?

Na gut, but nothing about transition from traction mode to braking.
As that CPH is a kind of joystick, driver can advance it anyway, but controller will switch cirquits at defined sequence with defined delays, when needed.
Indirect power control.
Dumb-proof.

[R H Steele]

[Admin Comment -- posts split from In-Cab Dynamic Brake Display error In-Cab Dynamic Display Please discuss Dynamic Brake Delay time in this thread. Thank You ]

[pschlik]

Getting this back on track...

Yes, there should be a delay between taking power and dynamic brakes. The reasons behind this are complex but it's vital to wait in order to have safe and comfortable operations.

But no, the dynamic brake handle should not be locked to 0% during the setup time (if the dynamic brake handle is at 0%, the dynamic brakes should be turned off!) Movement should be entirely free during setup, even increasing all the way to 100%.

Changing the dynamic brake behavior should be done such that 0% corresponds to off, and moving from 0% to any higher % should trigger setup. Setup should not occur with the dynamic brake at 0%.
The setup can stay as a timer (for the sim purposes that gets the idea across) but during setup the dynamic brake handle should not be locked in place.
Once the setup timer is complete, the dynamic brake force should swiftly (rate of change determined by a parameter in .eng file??) increase to the level of force appropriate for the current dynamic brake % (which, because the player can move the handle, could feasibly be anything from 1% to 100%). If at any point, even during setup, the dynamic brake is moved back to 0%, the dynamic brake force should be swiftly cut and the throttle can be moved from idle.

And if we want to get really complex, there should technically be an "anti-setup" timer that prevents tractive force from being applied until the dynamic brakes have been off for X seconds.

[engmod]

>The reasons behind this are complex

Lets simplify it a bit:-

DC loco

In a dc loco under power there is current flowing in the alternator and motor.
When power is turned off, back to notch 0, it takes some time for the current to stop.
If the switch is made immediately, arcing will occur and damage switchgear, commutator and any inline relays.

AC loco

Does not have current flow problems, current stops immediately.
No need for dynamic timer.