Class 390 boost mode?

[SolomonSouth]

I just want someone to enlighten me on the 390 boost mode.

How much difference does it make?
Does it wear the train out if you keep it on too long?
Does it run on a timer (i.e. you have to turn it on every 30 seconds?)
Do drivers ever use it in service if they need to make up time?

I just wanted to know more about it. I already heard that it only has an effect after 45mph. Is this true? If so, it seems strange that it doesn't boost the acceleration from a stand.

 

[Toby268]

It gives the train 20% more power from a standing start.

It’s only used for late running, I can’t think of the figure for how late the train is supposed to be before it’s used but it’s pretty low.

It can stay on as long as necessary.

 

[PudseyBearHST]

Eco/boost mode is the same to about 50/60mph, can’t remember the exact speed but it’s there abouts. Then boost mode accelerates a bit faster, 20% sounds about right.

You can use it when you want pretty much. It does make a noticeable difference but in the grand scheme of things, you’re not really going to make up that much time. There are certain fault conditions where Boost Mode will automatically come and stay on. And vice versa.

 

[hexagon789]

According to the Railway Performance Society - power output is unrestricted to 45mph, above that 'Eco' Mode restricts to 85% power.

Some drivers prefer to run in 'Boost' normally.

 

[SolomonSouth]

Some drivers prefer to run in 'Boost' normally.

Can't be good for the unit; it would probably cause excess wear on the motors!

 

[hexagon789]

Can't be good for the unit; it would probably cause excess wear on the motors!

'Boost' is a bit of a misnomer. Really it simply runs the unit at normal power rating, it doesn't temporarily uprate the motors in the same way boost did on the APT-P.

'Boost' is simply normal power, enough for 140mph as designed, 'Eco' simply restricts power over 45mph to a level more commensurate with the requirements for 125mph.

 

[Sorcerer]

'Boost' is simply normal power, enough for 140mph as designed, 'Eco' simply restricts power over 45mph to a level more commensurate with the requirements for 125mph.

Is this something that is unique to the 390 or can it be found on 80x models as well given that both trains were built with 140mph capability but only operate at 125mph in service?

 

[hexagon789]

Is this something that is unique to the 390 or can it be found on 80x models as well given that both trains were built with 140mph capability but only operate at 125mph in service?

It isn't a unique feature to purely the Class 390s (some other classes current and historic have/had something similar), but 80x don't have an equivalent.

 

[Sorcerer]

It isn't a unique feature to purely the Class 390s (some other classes current and historic have/had something similar), but 80x don't have an equivalent.

Thanks for the info. I imagine given how a boost mode isn't really a boost but more just a train working at full power that it won't really be a thing of the future since trains are getting more efficient and won't need to be restricted with an eco mode.

 

[bahnause]

It is not entirely clear to me how energy is to be saved to a greater extent with reduced power on an electric train. With electric vehicles, the ratio between power and consumption remains more or less the same. Depending on the optimal operating range of the converters, it may be possible to save a little.

 

[SansHache]

The introduction of Boost/Eco mode evolved from energy consumption measurements performed on 390049 in 2007. Net consumption was compared for multiple runs on different routes over several weeks and it was observed that the consumption was lower when operating with one of the six Traction Converters isolated. This was not in line with the predicted performance, but the results were consistent.
The trains were designed to be able to meet the PUG2 (140mph) journey times with one Traction Converter isolated. The tests in 2007 pre-dated the introduction of the speeded-up VHF timetable, so there was plenty of slack in the timetable. It was concluded that the trains were using more energy with all Traction available as they were frequently running ahead of schedule, requiring the trains to slow to get back totheir scheduled path. This effect was mitigated to some extent when operating with one Traction Converter isolated (5/6ths power).
Virgin were keen to take advantage of the reduced consumption as they were planning to switch over to metered energy measurement on the Class 390 trains.
The Traction software was modified to introduce a new "Power Saver" mode, that limited the train to 5/6ths power when all Traction Converters were operating. This did not affect the Tractive Effort at starting, and only came into effect at speeds above 45mph. This is set as the default operating mode, but the driver can select full power via a button on the Driver's Display screen. If one or more Traction Converters fail, the remaining Traction Converters revert to full power automatically.
"Power Saver" and "Normal" mode were re-branded as "Eco" and "Boost" when the function was introduced across the Class 390 fleet (positive marketing).
It was never possible to fully validate the potential energy savings as the VHF timetable was introduced around the same time as the Traction software was updated, bringing a significant change in the duty cycle.
However, one significant benefit of operation in "Eco" mode was the reduction in peak current in the Traction Converters. This improved the thermal performance (and hence reliability) of the Main Transformer and the controlled rectifier power module.

 

[AM9]

The introduction of Boost/Eco mode evolved from energy consumption measurements performed on 390049 in 2007. Net consumption was compared for multiple runs on different routes over several weeks and it was observed that the consumption was lower when operating with one of the six Traction Converters isolated. This was not in line with the predicted performance, but the results were consistent.
The trains were designed to be able to meet the PUG2 (140mph) journey times with one Traction Converter isolated. The tests in 2007 pre-dated the introduction of the speeded-up VHF timetable, so there was plenty of slack in the timetable. It was concluded that the trains were using more energy with all Traction available as they were frequently running ahead of schedule, requiring the trains to slow to get back totheir scheduled path. This effect was mitigated to some extent when operating with one Traction Converter isolated (5/6ths power).
Virgin were keen to take advantage of the reduced consumption as they were planning to switch over to metered energy measurement on the Class 390 trains.
The Traction software was modified to introduce a new "Power Saver" mode, that limited the train to 5/6ths power when all Traction Converters were operating. This did not affect the Tractive Effort at starting, and only came into effect at speeds above 45mph. This is set as the default operating mode, but the driver can select full power via a button on the Driver's Display screen. If one or more Traction Converters fail, the remaining Traction Converters revert to full power automatically.
"Power Saver" and "Normal" mode were re-branded as "Eco" and "Boost" when the function was introduced across the Class 390 fleet (positive marketing).
It was never possible to fully validate the potential energy savings as the VHF timetable was introduced around the same time as the Traction software was updated, bringing a significant change in the duty cycle.
However, one significant benefit of operation in "Eco" mode was the reduction in peak current in the Traction Converters. This improved the thermal performance (and hence reliability) of the Main Transformer and the controlled rectifier power module.

So in 'boost' mode all used parts of the traction system are still working within their continuous power ratings, (or maybe their 1 hour ratings with most of the normal stopping patterns and the gradient profile of the routes covered)?

 

[SansHache]

So in 'boost' mode all used parts of the traction system are still working within their continuous power ratings, (or maybe their 1 hour ratings with most of the normal stopping patterns and the gradient profile of the routes covered)?

Yes, Boost mode is the Traction characteristic that was in use from entry into service through to 2008. This characteristic was used when predicting the original journey times for the PUG1 (125mph) and PUG2 (140mph) WCML upgrades, and determined the design limits for the Traction equipment.
As has been mentioned above, some drivers prefer to select Boost mode as their default. The train automatically reverts to Eco once the cab is closed down (unless there is a Traction fault that limits performance).
The Class 390 Power Brake Controller has 4 indented Traction notch positions. Eco mode limits the Tractive Effort to the equivalent of notch 3.3 when notch 4 is selected at speeds above 45mph.
In practice operation in Eco mode has minimal effect on journey time, adding less than 2 minutes to a typical London - Glasgow journey.

 

[bahnause]

However, one significant benefit of operation in "Eco" mode was the reduction in peak current in the Traction Converters. This improved the thermal performance (and hence reliability) of the Main Transformer and the controlled rectifier power module.

How does the derating work together with regenerative braking? Does is always ramp up to the Boost Mode while braking? The energy saving measures we put into a lot of our traction included higher regenerative brake power ratings (6400kW -> 7000kW) and the disabling of a set of traction converters under partial load scenarios.

 

[SansHache]

How does the derating work together with regenerative braking? Does is always ramp up to the Boost Mode while braking? The energy saving measures we put into a lot of our traction included higher regenerative brake power ratings (6400kW -> 7000kW) and the disabling of a set of traction converters under partial load scenarios.

Regenerative braking is not affected by selection of Boost/Eco mode. There was some consideration of enhancing regen braking performance, but this was constrained by torque limitations on the cardan shaft and gearbox and adhesion performance.

 

[PudseyBearHST]

Yes, Boost mode is the Traction characteristic that was in use from entry into service through to 2008. This characteristic was used when predicting the original journey times for the PUG1 (125mph) and PUG2 (140mph) WCML upgrades, and determined the design limits for the Traction equipment.
As has been mentioned above, some drivers prefer to select Boost mode as their default. The train automatically reverts to Eco once the cab is closed down (unless there is a Traction fault that limits performance).
The Class 390 Power Brake Controller has 4 indented Traction notch positions. Eco mode limits the Tractive Effort to the equivalent of notch 3.3 when notch 4 is selected at speeds above 45mph.
In practice operation in Eco mode has minimal effect on journey time, adding less than 2 minutes to a typical London - Glasgow journey.

So in power notches 1-3, eco mode and boost mode are identical? It’s only when notch 4 is selected that it essentially caps it at notch 3.3 when using eco mode? Or is it 85% max at all notches. Thanks

 

[SansHache]

So in power notches 1-3, eco mode and boost mode are identical? It’s only when notch 4 is selected that it essentially caps it at notch 3.3 when using eco mode? Or is it 85% max at all notches. Thanks

Yes, that is correct, Eco mode only comes into effect when accelerating in notch 4 at speeds above 45mph. At lower power demands Eco and Boost performance is identical.

 

[PudseyBearHST]

Yes, that is correct, Eco mode only comes into effect when accelerating in notch 4 at speeds above 45mph. At lower power demands Eco and Boost performance is identical.

Thank you!

 

[bahnause]

Regenerative braking is not affected by selection of Boost/Eco mode. There was some consideration of enhancing regen braking performance, but this was constrained by torque limitations on the cardan shaft and gearbox and adhesion performance.

Thank you for the info. I consider the Class 390 and our RABDe500 to be similar animals. The torque limit wasn't changed, only the power rating was increased (regen braking only). Maximum regen braking force is now reached at a higher speed than before. Further energy savings were achieved by adjustments in the control system. In the first 50% of the control path, only the regenerative brake is applied instead of a specific deceleration value. Only when the wheelslip occurs the air brake is used to compensate. The speed control also only accesses the regenerative brake.

 

[PudseyBearHST]

Yes, that is correct, Eco mode only comes into effect when accelerating in notch 4 at speeds above 45mph. At lower power demands Eco and Boost performance is identical.

Is there any reason why boost mode might be disabled and not able to be selected via the TCMS? Is it to do if the temperature is too high or a deliberate software update preventing drivers from using boost mode unnecessarily? Thanks

 

[SansHache]

Is there any reason why boost mode might be disabled and not able to be selected via the TCMS? Is it to do if the temperature is too high or a deliberate software update preventing drivers from using boost mode unnecessarily? Thanks

Boost mode is disabled at high external ambient temperatures to prevent over-stressing of the Traction equipment.

 

[PudseyBearHST]

Boost mode is disabled at high external ambient temperatures to prevent over-stressing of the Traction equipment.

Very interesting, thanks!