System having a variable frequency power distribution bus for driving a variable speed motor

1. A method for supplying power to a variable speed motor for rotating a shaft, comprising:

generating an A/C output having a variable frequency corresponding to speed of a prime mover, the speed of the prime mover being equal to or greater than a predetermined speed limit;

distributing the A/C output of the prime mover to the variable speed motor such that the speed of the variable speed motor is varied relative to the frequency of the A/C output;

electrically disconnecting the variable speed motor from the A/C power when the speed of the prime mover being used to drive the variable speed motor is equal to or within a predetermined range of the predetermined speed limit; and

distributing an alternate A/C output to the variable speed motor after the A/C power is electrically disconnected from the variable speed motor.

2. The method according to claim 1 , wherein distributing the alternate A/C output includes distributing the alternate A/C output to the variable speed motor when the speed of the prime mover is less than the predetermined speed limit.

3. The method according to claim 1 , further connecting the alternate A/C output to the variable speed motor via a different conductive path than a conductive path that delivers the A/C power to the variable speed motor when the speed of the prime mover is less than the predetermined speed limit.

4. The method according to claim 1 , further comprising:

generating a single frequency A/C output based on the variable frequency A/C output of the prime mover; and

driving an auxiliary load with the single frequency A/C output.

5. The method according to claim 1 , wherein distributing the alternate A/C output to the variable speed motor includes distributing the alternate A/C output in a parallel manner with respect to the A/C output.

6. The method according to claim 5 , further comprising:

electrically disconnecting the A/C output from the variable speed motor; and

distributing the alternate A/C output to the variable speed motor after the variable speed motor is disconnected from the A/C output.

7. The method according to claim 1 , further comprising distributing the A/C output and alternate A/C output to a second variable speed motor.

8. The method according to claim 1 , wherein distributing the A/C output and alternate A/C output to the second variable speed motor includes distributing the A/C output and alternate A/C output to the second variable speed motor in series with the variable speed motor.

9. A method for supplying power to a variable speed motor for rotating a shaft, comprising:

generating a plurality of A/C outputs having respective variable frequencies corresponding to the speed of the respective prime mover, the speed of each of the prime movers being equal to or greater than a predetermined speed limit,

selectively varying speed of the variable speed motor relative to the frequency of the combined A/C outputs of the prime movers;

electrically disconnecting the variable speed motor when the speed of a prime mover being used to drive the variable speed motor is equal to or within a first predetermined range of the predetermined speed limit; and

distributing an alternate A/C output to the variable speed motor after the variable speed motor is disconnected.

10. The method according to claim 9 , wherein distributing the alternate A/C output to the variable speed motor includes distributing the alternate A/C output in a parallel manner with respect to the A/C output.

11. The method according to claim 9 , further comprising:

electrically disconnecting the A/C output from the variable speed motor; and

distributing the alternate A/C output to the variable speed motor after the variable speed motor is electrically disconnected from the A/C output.

12. The method according to claim 9 , further comprising distributing the A/C output and alternate A/C output to a second variable speed motor.

13. The method according to claim 12 , wherein distributing the A/C output and alternate A/C output to the second variable speed motor includes distributing the A/C output and alternate A/C output to the second variable speed motor in series with the variable speed motor.

14. The method according to claim 9 , further comprising:

generating a single frequency A/C output based on the variable frequency A/C output of the prime mover; and

driving an auxiliary load with the single frequency A/C output.

15. The method according to claim 9 , wherein distributing the alternate A/C output includes distributing the alternate A/C output to the variable speed motor when the speed of the prime mover is less than the predetermined speed limit.

16. A method of manufacturing a power distribution system for supplying power to a variable speed motor for rotating a shaft, said method comprising:

providing a variable speed prime mover adapted to generate an A/C output having a variable frequency corresponding to the speed of the prime mover;

electrically connecting a power switch to the variable speed prime mover;

electrically connecting a power distribution bus to the A/C output of the prime mover and, via the power switch, to the variable speed motor;

electrically connecting a variable frequency drive to the A/C output of the prime mover via the power distribution bus; and

electrically connecting a transformer to the power distribution bus; and

electrically connecting a second variable frequency drive to the transformer to provide for driving auxiliary loads.

17. The method according to claim 16 , further comprising connecting a controller to the power switch and to the variable frequency drive, the controller, when operated, is configured to selectably engage and disengage the power switch to apply and remove the A/C output from the variable speed motor.

18. The method according to claim 17 , further comprising:

electrically connecting a second power switch between the variable frequency drive and the variable speed motor; and

electrically connecting the controller to the second power switch, wherein the controller is configured to engage and disengage the second power switch in a substantially opposite manner to that of the power switch.

19. The method according to claim 16 , further comprising connecting a second variable speed motor to the power distribution bus.