30,000 HP motor starting

[rconnett]

This question may be valid for here or the power engineering forum (where I posted it). See link below.

http://www.eng-tips.com/viewthread.cfm?SQID=100545&SPID=238&page=1

Thanks!

 

[aolalde]

For 30,000 Hp Synchronous motor the inrush kVA should be around 5 per HP and PF around 0.4.
The required kVA = 30000*5 = 150,000
KW=150,000*.4 = 60,000
KVAR = 137,500
If 80% is corrected with a capacitor bank, the size of it will be; 110,000 kVA.

If the motor starts with the shaft released, Friction and windage losses must be provided, considering those 1% of full load F&WL= 3,000 HP. That will be the minimum size of a pony motor, if you add a VFD the acceleration to synchronous speed will be very smooth for the substation. A clutch (fluid drive?) is needed to engage gradually the load after the motor is synchronized to the line.

I consider the option of pony motor- clutch more reliable. The connection and disconnection of the capacitor bank could bring lots of transient problems and the acceleration to synchronism and engage of the full load still must be solved.