Class 91 traction motor query

[43074]

Can anyone tell me whether the Class 91 traction motors are ac or dc? Thanks in advance.

 

[Bald Rick]

DC. But bloody big ones.

 

[gimmea50anyday]

DC. Which explains their bulk ness!!!

At the time of introduction the motors were pretty much at the limit of DC motor technology while AC traction was untried technology in this country and little understood. Today AC traction is pretty much standard as the motors are significantly smaller for comparable power output and use.

 

[captainbigun]

Biggest DC motor in the UK, at least.

 

[andyfrommk]

You might find this program on the building of the Intercity 225 interesting
Intercity 225 Documentary 'Running to time' Part 2 of 4
I wouldn't bother watching the first part, hardly any tech, mostly yakk.

 

[507 001]

You might find this program on the building of the Intercity 225 interesting
Intercity 225 Documentary 'Running to time' Part 2 of 4
I wouldn't bother watching the first part, hardly any tech, mostly yakk.

Thats a very interesting documentary, I hadn't realised that the motor arrangement was different from APT-P's.

The bloke talking about the design of the loco was interesting

 

[43074]

Thanks for the informative responses. The 'Running to Time' documentary is fascinating.

 

[D365]

We've just been taught DC motors in Physics and I asked if we would do AC at all, sadly not... 91 was pretty much the last DC design in Britain with Networker introducing AC and GTO

 

[hedpe]

The AC motors in Networkers are known as "squirrel cages". They are relatively maintenance-free compared to their larger, older DC brethren's which need brushes changed, flash-over inspections etc

 

[colchesterken]

How about rebuilding class 90 & 91 with an a/c traction package with 90s upgraded to 125 mph..must be cheaper than buying in new locos..I believe the 90s are shaft driven,
so a complete bogie overhall strip out the d/c gear and replace with a/c traction..job done

 

[ainsworth74]

must be cheaper than buying in new locos.

You sure about that? Sounds like a hell of a complex operation to me!

 

[doubleamber]

AC drives are also cheaper to build, when 90/91's were built the technology was no around for the power output needed to run AC motors, DC is very good for low down power but as has been said, needs more inspections and parts.