Starting a 250KW Y-D motor with 1MW Generator

Can the star-deltas be changed for soft-starts and the motors started in sequence, so that motor 2 is delayed until motor 1 is up-to-speed? This change would improve the chances, as would substituting variable-frequency drives [VFD]. VFDs have rather more configurable parameters than soft-starters.

The mechanical nature of the load is also of interest; if the motors are connected to something having a big flywheel then the starting effect will be more severe than if they were connected to a low-inertia device like a centrifugal pump, for example.

Is it possible to run 2 nos. 250KW LT motor (415V), having star-Delta connection, with 1MW Generator.

Regards,

What is the LRI for the motors? I assume that you would not attempt to start both motors at the same time. Intuitively I would say you could run the motors, but it is unlikely that you would start them.

You will need to specify the "load " starting torque to determine the minimum starting torque of the motor

They should run ok depending on what other load you have connected to the generator. Starting would be far better if you change the star delta starters for electronic. Especially important if you are starting centrifugal pumps as the changeover timing s-d can be critical if you get it wrong the generator could drop out at this point. More likely when you start the second motor. If you are running Centrifugal pumps or Fans cut the star time down to as short as possible. If you have a high inertia load leave the star time long.

One to full load-PAUSE.

Then same way y/ for #2 !

Sure

Yes, but both the motors not simultaneously. You should ensure that Generator excitation and governor should be able to provide extra power and have capacity for providing short time duration power more than the motor acceleration time. Better do some ETAP study, giving detail of Generator, motor/load characteristic curve etc.

You should have no problem starting 2 250kw motors at the same time with a 20-25% voltage dip assuming not flywheel loadings.

One 250 kW motor if started DOL would draw approx 2.4 mVA and if started in star then approx 1.3mVA. Some other form of assisted would be required. An auto transformer starter on 50% tap [assuming FLI = 500amps] would draw about 600.0kVA starting and should not represent a problem for the generator. Will this provide sufficient torque to accelerate your load? It will depend on the load torque/speed curve. Other options are VVVF drive as has already been mentioned. A primary reactor starter may also do the job, as the starting current could be limited to the FL amps. Again, will this provide sufficient torque to accelerate your load? It will depend on the load torque/speed curve.

Greg lynch

I would suggest using one motor (one which is used first) on star-delta and the second one on softstarter. Another way is to use softstarters ( with bypass contactors to bypass the softstarter) on both motors. 1 MW gennie ( unless it is brand new) will be stretched if use both motors with star-delta starter. Good luck !! Chaterpilar