Class 365 acceleration

[Emblematic]

I can't remember where I read it, but it was *definitely* referring to class 323. (Unless it was a typo, of course!).

Porterbrook's brochure mentions an upgrade of the traction control from older GTO thyristors to IGBT (large power transistors.) The motors would be unchanged. Almost any unit with GTOs could be considered for this change as the technology is obsolete and the spares supply is largely made up of recycled components. Class 465 Networkers were changed to IGBTs some time ago.

The GTO drive train used on the two powered vehicles is common with other units worldwide; however these are steadily being upgraded. This means there is a good supply of spares for the foreseeable future but the reliability of the equipment could be improved. Two offers are being considered to change the key GTO drive components for modern IGBTs, or replace the whole traction package for new equipment of the latest design.

 

[D365]

Class 465 Networkers were changed to IGBTs some time ago.

... Once again, only the BREL/ABB-manufactured 465/1 and /2 subclasses (as built with Brush traction equipment) have been refitted. For other Networker types (465/2, 466, 365) their component reliability hasn't been deemed to be an issue.

A link is provided here to the aforementioned Porterbrook/Class 323 brochure.

 

[notadriver]

I've read some articles which discuss field weakening in AC motors but it's complex and I don't think they tried it in earlier designs. The power curve of an AC motor is different to DC. It rises up to a certain speed and then stays constant right up to rated top speed. DC motors have a power spike in the lower speed ranges but power tails off rapidly at higher speeds hence field weakening to reduce the back EMF.

 

[Emblematic]

... Once again, only the BREL/ABB-manufactured 465/1 and /2 subclasses (as built with Brush traction equipment) have been refitted. For other Networker types (465/2, 466, 365) their component reliability hasn't been deemed to be an issue.

A link is provided here to the aforementioned Porterbrook/Class 323 brochure.

Apologies, didn't mean to contradict, I should have specified just some of the 465s - and thanks for the link which I intended, but forgot to add

My point was just that it's a possible and reasonable upgrade, if reliability is an issue. The earlier posts indicate some problems with 365s, and while degraded performance may not be a concern when operating alongside DC motored stock (317/321) it may become so when interworking with Aventras and Desiro Cities.
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I've read some articles which discuss field weakening in AC motors but it's complex and I don't think they tried it in earlier designs. The power curve of an AC motor is different to DC. It rises up to a certain speed and then stays constant right up to rated top speed. DC motors have a power spike in the lower speed ranges but power tails off rapidly at higher speeds hence field weakening to reduce the back EMF.

The latest development in AC traction is the permanent magnet motor. These have no field coils, so field weakening cannot be applied.

The controls and terms/labels of the early AC motored units were doubtless designed to be as familiar as possible to drivers used to DC motors, I doubt it's anything more than that.

 

[bramling]

Porterbrook's brochure mentions an upgrade of the traction control from older GTO thyristors to IGBT (large power transistors.) The motors would be unchanged. Almost any unit with GTOs could be considered for this change as the technology is obsolete and the spares supply is largely made up of recycled components. Class 465 Networkers were changed to IGBTs some time ago.

Thanks for the info/link. Is this actually going ahead? Presumably this would result in the 323s losing some or all of their distinctive sound?

I seem to recall the remaining Networkers were being considered for change some time ago, but this now seems to have fallen by the wayside. Is it correct to say the ABB traction networkers (465/0 and 465/1) were done more due to reliability issues than any other reason?

There is talk of the 96 tube stock also losing their GTO thyristors, although I haven't seen any definitive plans so presume this will be some time in the future, if it happens.

 

[Emblematic]

Thanks for the info/link. Is this actually going ahead? Presumably this would result in the 323s losing some or all of their distinctive sound?

I seem to recall the remaining Networkers were being considered for change some time ago, but this now seems to have fallen by the wayside. Is it correct to say the ABB traction networkers (465/0 and 465/1) were done more due to reliability issues than any other reason?

There is talk of the 96 tube stock also losing their GTO thyristors, although I haven't seen any definitive plans so presume this will be some time in the future, if it happens.

These enhancements listed in the brochures are mainly for the benefit of future franchise bidders to include in their tenders. Not many have been implemented to date.

Whether the 323 sound changes will depend on whether the whole traction package, or just the power stage, is changed.

The Networker upgrades were undoubtedly reliability driven, the traction system as a whole was too unreliable rather than a specific issue with the GTO components. The new package doesn't need fan cooling, and a degree of component redundancy was added, so there's less to go wrong and less impact when it does.

The 96ts upgrade was something mentioned in Modern Railways a while back, I don't recall the reasoning but it stated that the order for additional trains would include traction upgrade of the present fleet. The actual ITT issued covers a wide range of options - from a minimum of 5 trains for the Northern line extension, up to 68 new trains and the possibility of complete Jubilee fleet replacement and cascade - but no mention of upgrades at all.