Class 390 vs "other" Pendolinos - why the lower rated traction motors?

[slipdigby]

Something that has puzzled me having ridden on a couple of examples of similar generation Pendolinos in Europe (Alfa Pendular on CP, 310s in Slovenia) is why the traction motors on a 390 are rated at 425kw vs 500kw on Continental European examples? I'm assuming that this is related to loading guage issues, but haven't been able to identify any definitive evidence one way or another. Can anyone assist?

With Thanks!
Slip

 

[Sorcerer]

I'm not an expert but I imagine this sort of stuff would be less related to the loading gauge and more the electrical engineering side of things such as the different voltages of overhead lines on the continent, which can vary between 3kv to 15kv to even 25kv all for one unit, as well as the different propulsion systems. Continental Pendolinos also used different traction motors. The CD 680 traction system (which is 490kw rather than the 500kw you mentioned) uses phase fired thyristor control. The three-car Renfe Class 490 uses 4 asynchronous three-phase electric motors while the ten-car Alfa Pendular uses 8. By contrast the Class 390 uses Alstom's Onix drive system to control 12 traction motors. I can't say whether or not they are different enough to be factors in the different traction motor rating of each train, but I would be surprised if this combined with the different overhead line specifications for different Pendolinos didn't at least play a part in it.

 

[SansHache]

Something that has puzzled me having ridden on a couple of examples of similar generation Pendolinos in Europe (Alfa Pendular on CP, 310s in Slovenia) is why the traction motors on a 390 are rated at 425kw vs 500kw on Continental European examples? I'm assuming that this is related to loading guage issues, but haven't been able to identify any definitive evidence one way or another. Can anyone assist?

With Thanks!
Slip

The original Train Infrastructure Interface Specification imposed a 6.7MW maximum power limit for the train. This is split approximately 6MW for Traction and 700kW for the train auxiliaries (heating, lighting and other control systems). The 425kW rating for the motor is the output power. The efficiency of the overall Traction drive system is typically 85% so 12 motors at 425kW output equates to a total input power of 6MW. When the 11-car trains were introduced in 2012 the maximum power limit was increased to 7.8Mw to take account of the increase from 6 to 7 Traction Converters and the auxiliary loads on the two additional vehicles.

The Class 390 traction motors are capable of much higher output but other elements of the electrical and mechanical drive are designed specifically for the 425kW rating.

 

[slipdigby]

Fantastic, thank you both.

With best regards,
Slip

 

[CharlieSpotted]

The original Train Infrastructure Interface Specification imposed a 6.7MW maximum power limit for the train. This is split approximately 6MW for Traction and 700kW for the train auxiliaries (heating, lighting and other control systems). The 425kW rating for the motor is the output power. The efficiency of the overall Traction drive system is typically 85% so 12 motors at 425kW output equates to a total input power of 6MW. When the 11-car trains were introduced in 2012 the maximum power limit was increased to 7.8Mw to take account of the increase from 6 to 7 Traction Converters and the auxiliary loads on the two additional vehicles.

The Class 390 traction motors are capable of much higher output but other elements of the electrical and mechanical drive are designed specifically for the 425kW rating.

Just passing through, but what a fab, informative and easy to understand answer this is... @SansHache

 

[SansHache]

Just passing through, but what a fab, informative and easy to understand answer this is... @SansHache

No problem, I have been involved with Pendolinos since 1998 when they were only scribbles on scraps of paper (no fag packets allowed in the office).

 

[Railperf]

No problem, I have been involved with Pendolinos since 1998 when they were only scribbles on scraps of paper (no fag packets allowed in the office).

I'm guessing the 140mph top speed specified requires a lower maximum power output than the 250km/h (155mph) top speed specified for most European versions of Pendolino.

 

[SansHache]

I'm guessing the 140mph top speed specified requires a lower maximum power output than the 250km/h (155mph) top speed specified for most European versions of Pendolino.

Yes, that is correct. The power requirement increases significantly with maximum speed as a higher tractive effort is required to overcome the aerodynamic forces.
The Traction drive architecture is also a limitation on the top speed of the Pendolino trains. The traction motors are body-mounted in order to accommodate the tilt equipment on the bogie. The motors drive the inner axle of each bogie on the motored cars via a cardan shaft and right-angled gearbox. This limits the number of motored axles on the trainset.
When the Class 390 trains were originally introduced as 8-car trains there were 6 motor cars and 2 transformer cars giving 12 motored axles from 32 (37.5%). This limits the acceleration performance at lower speeds. Fitting more powerful motors does not necessarily help with the acceleration as the higher tractive effort cannot be utilised reliably when adhesion conditions are poor.

 

[Railperf]

Yes, that is correct. The power requirement increases significantly with maximum speed as a higher tractive effort is required to overcome the aerodynamic forces.
The Traction drive architecture is also a limitation on the top speed of the Pendolino trains. The traction motors are body-mounted in order to accommodate the tilt equipment on the bogie. The motors drive the inner axle of each bogie on the motored cars via a cardan shaft and right-angled gearbox. This limits the number of motored axles on the trainset.
When the Class 390 trains were originally introduced as 8-car trains there were 6 motor cars and 2 transformer cars giving 12 motored axles from 32 (37.5%). This limits the acceleration performance at lower speeds. Fitting more powerful motors does not necessarily help with the acceleration as the higher tractive effort cannot be utilised reliably when adhesion conditions are poor.

12 motored axles a huge improvement from the 4 motored axles in loco hauled days.

ETR 485 and 610s accelerate more swiftly than ours..but railhead conditions in Southern Italy are better.