Atomic Systems

A British Class 66 is like a US SD70 when it comes to prime mover, but has DC traction instead of AC.

Can somebody explain why the Class 66 draws up to 4000 amps while the SD70 seems limited to 1500 (at least in TS17, which simulation cannot always be relied on)?

21C164FighterCommand wrote:A British Class 66 is like a US SD70 when it comes to prime mover, but has DC traction instead of AC.

That is like saying a Class 20 and a Class 40 are identical as they both have an English Electric prime mover

The Class 66 has an EMD 12N-710G3B-EC developing 3.300 hp & a Continuous rating 58,500 lbf at 15.9 mph
The SD 70 has an EMD 16-710-G3 which has 16 cylinders compared with the 12 in the Class 66 and develops 4.000 hp giving a Continuous rating 137,000 lbs @ 12 mph
The earlier SD70, SD70M have DC traction motors like the Class 66 but of a different design

21C164FighterCommand wrote: Can somebody explain why the Class 66 draws up to 4000 amps while the SD70 seems limited to 1500 (at least in TS17, which simulation cannot always be relied on)?

Error in TS2017?

Peter

Generator/Alternator output versus single motor amps possibly?

Maybe that's why he used "like" rather than "identical" Peter.
Does anybody have any verifiable specs for both locomotives? ...... perhaps the SD70 has a limiting device in real life so the game is replicating that; visually at least if not in practice.

I have been searching for operating manuals, but not found them yet.

I suppose on the Class 66, alternator current is measured, while on the SD it is current of a single traction motor.

Is measuring the generator/alternator current the norm on UK locomotives?

Or perhaps they use different voltage levels?

https://en.wikipedia.org/wiki/EMD_Class_66

https://en.wikipedia.org/wiki/EMD_SD70_series