Inadequate Power

If you can maintain synchronization, you should have enough capacity to start and run the motor. Generally, you need about 2 to 3 times the full load kw of the motor.

First of all, read this thread: http://cr4.globalspec.com/thread/52712/RATTING-FOR-ALTERNATOR for required generating capacity for the motor starting.

Then,

1. As Wareagle already indicated, you can synchronize the generators and your total generating capacity is 1460 x 3 = 4380 KW which is enough to start the 600 KW motor.

2. You didn't mention the voltage; it seems the voltage is 11 KV (1825 / (1.732 x 95.9) = 11). The full load current (FLA) of 600 KW motor is then in the range of 50 A (600 / (1.732 x 11 x 0.8 x 0.8) = 49.2, with 80% efficiency). The maximum starting current may be 50 x 6 = 300 A (it is very common that starting current is 6 times of FLA). Why does the motor need 450-600 A starting current then?

3. However, if you have other loads in the system and need to start the motor with other loads running, I would suggest you to use VFD (Variable Frequency Drive) or Soft Starter for the motor. The selection of VFD or Soft Starter depends on other existing running loads in the system during the motor starting and the economic consideration.

- MS

Thanks for your swift reply, please still explain to me how you got the max. starting current, where did you get this formula?

best of regrds,

Mahdi.

First, WE and MS, Good shots! Now, where'd you get that 17 secs and why can't you delay each start to minimize the inrush to the overall load? Jim

1- Synchronization

2- VFD (soft starter)

3- Remove all load from motor (un-couple) upon start-up via pneumatic clutch for instance.

Apart synchronizing the generators try using a soft starter which can ensure gradual rise of current where u can set minimum value to 3or4PU .But whta is the driven eqipment .How long does the motor take to reach full or rated rpm.these are very important in any motor application

The driven equipment is an electric motor 600kw, and it needs 17sec. to acheive full rated RPM.

No, the question was "driven" not driver.

What is the 600kw motor turning? What work is the 600kw motor accomplishing?

If it requires 17 seconds to come up, it is likely starting under a heavy load

The electric motor is driving a huge fan.

Fan is a high inertia drive and will need a prolonged acceleration time.17seconds is a lot of time.Is it under DOL starting Pl? with a soft starter u can have a smooth starting but minimum starting voltage point needs to be calculated.this will require Torque vs speed curve of Fan superimposed on motor T_s curve.I suggest refer with fan details to motor and also to genset suppliers .A combined study will give a correct solution.

Regards

Its actually a FORCED DRAFT FAN.

OK a BIG fan.... So right back where we started, first be certain you are optimizing your power supply. Second look into a VFD, third you can look at mechanical solutions to lessen the start up torque spike. Third option has endless possibilities, just depends on your dimensional, time, and funds limitations.

Being a gear head, I would personally much prefer the later solution