Hi everyone,

I wish to thank you for your time. Please I need your help to solve this question.

I have a standard distribution system (11kV) making use of an islanded power plant (generator output 11kV) (See link below). The loads for each section are: 0.7MW, 1.1MW, 1.1MW, 0.9MW. Ahead of these loads are transformers of type DYg (11kV/433V, 1500kVA). The other loads are directly connected to the 11kV distribution system and are: 0.6MW (combined load), 3.2MW (Sag Mill), and 5.6MW(Ball Mill). When the ball mill starts, it uses a liquid resistance starter that demands 1.8 times normal load.

I need to determine the number of sets required to start the Ball Mill with a fully loaded plant in two cases: using diesel sets or using gas reciprocating engines.

Diesel sets: 1250 kVA, 11 kV, 50 hertz, power factor 0.8 and inertia constant 50.2 kg-m², damping ratio = 0.13.

Reciprocating engines: 5175 kVA, 11 kV, 50 Hertz, power factor 0.8 and inertia constant 1300 kg-m², damping ration = 0.13.

What should I calculate to find the number of sets?

Thanks a lot for your help.

http://files.engineering.com/getfil...86&file=distribution_system_diesel_vs_gas.png

 

Scientif... to begin discussion:

1) Does "Island Operation" mean only combustion-EG's as power source?

2) Worst-case; Ball-Mill start with 7MW on-line, including SAG-Mill?

3) Is B-M an Induction mtr, with liq-starter connected to stator?

4) Is B-M a Wound-Rotor mtr, with liq-starter connected to rotor slip-rings?

5) What is permmisible V-drop @ 11kV?

6) What is permissible V-drop @ 433V?

Regards,
Phil Corso