Hi all

i want to know that it can to replace a liquid starter (MW) with drive?

if it can, what ordering of siemens is response for it?

and what is requirments and notification for this replacement

Hello,

What do you mean by liquid starter?

Do you mean to say OCB?

Please provide more detail specifications of your liquid starter along with application. 

electrolytic starter (or Liquid starter) can be used to start slipring motors from 500 kW to 20,000

kW or higher.

It will supply the power necessary to drive the motor by resistance variation.

No. VFD could not be a alternate starter for slip-ring induction motor. In slip-ring induction motor OCB starter, resistance is gradually decreased from motor rotor circuit. In VFD, squirrel cage induction motors V/F Ratio is maintained. VFD basic application is to vary motor speed. Slipring induction motor OCB starter is to prevent motor inrush current within safe limit at the same time to provide additional torque while starting.

HTH. 

Jeff Casagrande

It is theoretically possible to run a VFD on a slipring motor by either shorting out the resistance connections or keeping a small fixed resistance connected.  This requires a great deal of motor expertise and should only be performed by a qualified expert (I am not an expert).

 This defects the purpose & application of slip ring induction motor & its OCB starter.

Not necessarily.  Vector control will give you high starting torque and limit inrush.  Slipring motors are useful for either high starting torque applications (cranes), or applications where high slip is required (press, shear) with direct online starting. When you short out the slipring wires, you are simply making a standard induction motor.  I've done this several times before on crane retrofits.

However, the OP is talking about 500-20,000 KW, which is way beyond my pay grade.

New question published by hieubenzspkt is split to a separate thread with the subject Need a Liquid Resistance Starters to start the motor ( power 800 kw, 6kv, speed: 1500 rpm) .

Best regards
Jen_Moderator