soft starters

  • Thread starter Siamak Tavakolie
  • Start date
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Thread Starter

Siamak Tavakolie

I want to know if soft starters have the facility for produce a stable, predefined, rpm against torque changing. If there is a brand having this specification please let me know. Thanks.
 
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VFD gives more, even adujstable speed.

Siamak Tavakolie wrote:
> I want to know if soft starters have the facility for produce a stable, predefined, rpm against torque changing. If there is a brand having this specification please let me know. Thanks.
 
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Nilesh Patel

Ques: I want to know if soft starters have the facility for produce a stable, predefined, rpm against torque changing. If there is a brand having this specification please let me know. Thanks.

Ans: I think No.
Because Soft starter is having only Ramp function generation block and it controls thyristors firing pulses and start the motor smoothly at the time of starting only.
But if you have any torque changing due to load then you have to go for the AC/DC drives to maintain the constant motor RPM , because Drives have Current/Torque Controller inside.

If you need more info on Drives which can fit into your application, pl. feel free to contact me.

Bye
Warm Regards,
Nilesh Patel
[email protected]utomation.com
Canada
Ph:1-905-712-9451
 
I am not sure of your question. Are you looking to continuously change motor speed or torque with a soft starter? If so, then no, a soft starter cannot do that without damaging the motor.

Or are you wanting to know if you can have a linear speed and/or torue acceleration ramp with a soft starter? If so, the answer is maybe.

There are several manufacturers who offer "tachometer feedback ramping" which will give you a linear speed ramp, provided that you install a tachometer on the motor or load shaft. Ask for that feature. Torque will vary as needed to increase speed.

If you want a linear Torque ramp, many of the more advanced digital microprocessor based soft starters can now provide that. This will apply a steadilly increasing amount of torque, but speed will be load dependant.

I do not know of any soft starter that does both. VF drives with vector or direct torque control can do that.
 
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