DC Bus voltages

[NP Red]

Check out the voltage on this self test video at notch 8.

http://www.youtube.com/watch?v=ga5G9C65uQ0&list=FL_WgQ4QQYf7LGwFu-g5Ybbw&index=3&feature=plpp_video

[KPykkonen]

Good point about constant DC bus voltage on AC machines - simplifies IGBT controls I imagine.

[oltmannd]

My recollection about AC4400s and SD80MACs was that the GEs ran a constant 1200 VDC and the EMDs 2500 VDC.  I have no idea about the current state of the art.

[erikem]

I seem to recall seeing EMD'S D-87 motors rated for 1400VDC, but don't recall seeing the limit for the 752's. Maximum output voltage is usually limited to what the motors can handle, but the ultimate limit would be set by when the magnetic circuit for the traction alternator/generator saturates.

I'm fairly sure that the inverter DC bus voltage is held constant on GE locomotives, there's not much to be gained from varying the input voltage with throttle notch with IGBT inverters.

- Erik

[KPykkonen]

Thanks, Erik.

Good point about AC vs. DC.  I think EMD machines top out at ~1465 V.  Per post above I was thinking GE loco's had higher max voltages.

On DC machines voltage will need to be whatever traction motors dictate according to track speed and state of "transition" for machines that implement transition in traction motors.  For AC machines I wonder if there are distinct voltage set points for each notch?...

[KPykkonen]

Thanks, Randy.

 

My thoughts were motor load at zero speed is all resistance, then inductance kicks in as wheels start to turn.  There must be current limits on alternator that kick in...I wonder what those are?

[erikem]

The question has different answers depending on whether the EVO has DC or AC traction motors. I have a vague recollection of 1400V max for the DC motors (though that might be for EMD's motors). I have heard that GE's AC locomotives use an 800 volt bus - this was from a presentation from a researcher at GE's research facility in Bangalore.

- Erik

[Randy Stahl]

I thought the GE's were 2400 volt ?

On an open circuit self test DC bus voltage is around 110 volts in notch one , I'm not sure what it is with a motor load but I assume it would be somewhat less, possibly even zero until the locomotive actually begins to move.

Randy

[KPykkonen]

What are max DC bus voltages for Evo-series locomotives?  I remember hearing around 2,000 VDC but can't find info on web any place.   

Also, anyone know what the same bus voltage is just before loco starts to move?

 

Thanks,

 

KPykkonen