Power output request - newish EMUs and DMUs

[hexagon789]

I bet the acceleration limitation control was somehow bypassed for that

Voyagers have an acceleration limitation control? Never come across that before, does it downrate the power output slightly in some manner?

 

[hexagon789]

I have seen and queried that data. It sems to match to 750hp engine outputs before downrating and before the use of acceleration rate control.
It is a shame the 22Xs have all been downrated this way.
Similarly i have seen a Class 221 0 to 60mph time of 58seconds pre engine downrate.
It has to be mentioned that these times were acheived with drivers making the effort to provide the fastest possible time.

I've no idea when they were taken, but I'm not sure RAIL Express has done it's 0-60 timings all that long compared to the age of the magazine itself. As to drivers making the effort I thought they simply took averages in each direction on level track to get their figures?

 

[Railperf]

I've no idea when they were taken, but I'm not sure RAIL Express has done it's 0-60 timings all that long compared to the age of the magazine itself. As to drivers making the effort I thought they simply took averages in each direction on level track to get their figures?

The author of that piece is someone i know very well. It was a one off run. And the published timing is from the single run. It has not averaged with an uphill run.
We try to use data from level track starts where possible.
Where a level start is not possible..then an uphill or downhill start is averaged with one in the opposite direction.

 

[hexagon789]

The author of that piece is someone i know very well. It was a one off run. And the published timing is from the single run. It has not averaged with an uphill run.
We try to use data from level track starts where possible.
Where a level start is not possible..then an uphill or downhill start is averaged with one in the opposite direction.

My mistake, I assumed it was done in the usual way. No wonder it made 60 in 53 seconds if it was downhill!

 

[Railperf]

My mistake, I assumed it was done in the usual way. No wonder it made 60 in 53 seconds if it was downhill!

Downhill or not, the figures are almost spot on with computer program that a colleague uses to calculate the performance based on power outputs. So i am led to believe that any time advantage gained with the downhill start is negligible.
I recently compared a recent Class 222 acceleration against the computers predicted acceleration rate in derate mode - and again the figures are surprisingly close give or take a second here and there - which gives me confidences that the performance modelling program is pretty accurate.

 

[hexagon789]

Downhill or not, the figures are almost spot on with computer program that a colleague uses to calculate the performance based on power outputs. So i am led to believe that any time advantage gained with the downhill start is negligible.
I recently compared a recent Class 222 acceleration against the computers predicted acceleration rate in derate mode - and again the figures are surprisingly close give or take a second here and there - which gives me confidences that the performance modelling program is pretty accurate.

I remember reading an article about the first use of computer modelling to calculate running times for the purpose of timetabling. This was first used by BR for the GEML in the early 1960s, the accuracy of the computer modelling compared to a timing run undertaken was very close indeed.

Interesting that 220s are actually faster than spec then.

 

[Railperf]

Voyagers have an acceleration limitation control? Never come across that before, does it downrate the power output slightly in some manner?

yes, as I understand it, this is an Alstom developed software that interfaces with the bombardier traction electronics to adjust the power downwards to maintain a pre-determined acceleration curve.
I was surprised at this, because i have noted that Voyagers will accelerate faster downhill. However I am assured that the rate of power applied downhill is a lot lower than it would be without the acceleration rate control. The example given was that a 220 with the power at maximum setting would be delivering only 81% power at 75mph down a 1 in 200 gradient.

 

[Railperf]

Interesting that 220s are actually faster than spec then.

PR machines like round numbers. Hence the Virgin PR people claiming 0 to 60mph in 60 seconds. Nice and easy for the public to remember. Of course - at the time, they were slightly faster on level track, and probably would still deliver 0 to 60mph in 60 seconds uphill too. My recent Class 220 run uphill was still close to 60 seconds despite acceleration rate control and any derate that incurs.

 

[43096]

yes, as I understand it, this is an Alstom developed software that interfaces with the bombardier traction electronics to adjust the power downwards to maintain a pre-determined acceleration curve.
I was surprised at this, because i have noted that Voyagers will accelerate faster downhill. However I am assured that the rate of power applied downhill is a lot lower than it would be without the acceleration rate control. The example given was that a 220 with the power at maximum setting would be delivering only 81% power at 75mph down a 1 in 200 gradient.

Voyagers have Alstom traction systems, do they not?

 

[hexagon789]

yes, as I understand it, this is an Alstom developed software that interfaces with the bombardier traction electronics to adjust the power downwards to maintain a pre-determined acceleration curve.
I was surprised at this, because i have noted that Voyagers will accelerate faster downhill. However I am assured that the rate of power applied downhill is a lot lower than it would be without the acceleration rate control. The example given was that a 220 with the power at maximum setting would be delivering only 81% power at 75mph down a 1 in 200 gradient.

That's quite interesting and indeed surprising because it negates any fuel economy from using gradients to help acceleration.

Is it even possible to get 100% derated power from them or does that require a substantial uphill gradient such as Lickey for the traction electronics to go - "hang on, more power needed"?

 

[hexagon789]

Voyagers have Alstom traction systems, do they not?

I know the motors are Alstom, ONIX 800s

 

[hexagon789]

PR machines like round numbers. Hence the Virgin PR people claiming 0 to 60mph in 60 seconds. Nice and easy for the public to remember. Of course - at the time, they were slightly faster on level track, and probably would still deliver 0 to 60mph in 60 seconds uphill too. My recent Class 220 run uphill was still close to 60 seconds despite acceleration rate control and any derate that incurs.

Good old PR, it's even more noteable that in this case they aren't exaggerating performance but rather underplaying it, quite unusual in that respect

 

[43096]

I know the motors are Alstom, ONIX 800s

I understood the entire traction system including inverters and what have you, is Alstom. At the time Bombardier didn’t own what was ADtranz so bought in the traction system.

 

[hexagon789]

I understood the entire traction system including inverters and what have you, is Alstom. At the time Bombardier didn’t own what was ADtranz so bought in the traction system.

Oh right, understood. Not sure then, I only remember the motor type is Alstom and the TMS is I believe Bombardier

 

[notadriver]

Good old PR, it's even more noteable that in this case they aren't exaggerating performance but rather underplaying it, quite unusual in that respect

Which trains have performance figures that have been exaggerated?

 

[hexagon789]

Which trains have performance figures that have been exaggerated?

Not perhaps in the general press, but there are certainly trains whose performance is less than it should be.