Electrics start more than they can pull; steam pulls more than it can start?

[railcat]

Can anyone weigh in on why this is the case?

I know that steam engines develop greater power at speed because the draught through the firebox is greater; simply greater combustion and more steam pressure, but why would electric motor torque decrease with speed?

thank you,

rcat

 

[bcp]

I think the limitation is overheating, not torque.

Bruce

 

[railcat]

I think the limitation is overheating, not torque.

Bruce

OK, so, under load, are traction motors basically at or near burning out? Or, are there limiters built in to their design to prevent them from working past a certain temperature limit?

 

[bcp]

All electric motors can produce more than continuous rated power for a short time without damage. The limitation is due to heat breaking down the insulation on the wires.

This can get a heavy train started moving, but that power level can't be continuously maintained without overheating the motors.

Bruce