[benu9714]

I read about the Oshkosh diesel electric truck (very little info available) which has a 400 hp diesel genset powering individual motors for multiple axles.

In this context I have two questions :
1. When the load on a a genset increases, does the engine speed increase to generate more power? If so, does the electricity frequency & voltage increase, and if so how do the motors react? If not, does the engine maintain a fixed speed, voltage and frequency, and respond to changing loads by changing the ampereage of the current?

2. is it possible to have multiple gensets running in parallel to drive multiple motors?

Please could someone answer these questions and/or provide links that give the answers? Thanks

[Rahul Rao]

Originally Posted by benu9714

In this context I have two questions :
1. When the load on a a genset increases, does the engine speed increase to generate more power? If so, does the electricity frequency & voltage increase, and if so how do the motors react? If not, does the engine maintain a fixed speed, voltage and frequency, and respond to changing loads by changing the ampereage of the current?

For this read details of how an inverter generator works. These generators normally have two or 3 fixed speeds.
Assume the 400 BHP is at 1500rpm. The engine will give best effeciency (gms/kw/hr) between 70% and 40% load. So when total load from motors is above 40% ie 160 HP it will be at 1500 rpm.
Now efficiency band of this engine in automotive application may have good efficiency from 1200rpm to 1700 rpm (most common for Medium speed long stroke engines) Then RPM will fall to 1200 rpm if load is below 160 HP.

Now if load is very low or negligible, the engine will go down to idling speed 600 RPM or so,[quote=benu9714;4763255]

Originally Posted by benu9714

2. is it possible to have multiple gensets running in parallel to drive multiple motors?
Please could someone answer these questions and/or provide links that give the answers? Thanks

Yes it is possible, power electronics has methods to co ordinate frequency of multiple gen sets, it is slowly gaining usage in big buildings, but it is not very common yet.


Rahul