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Liquid Resistance Starters


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#1 mike16

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Posted 01 October 2010 - 08:45 AM

Is it possible to use the same liquid resistance starter to start more than one motor, say 3 and assuming all the motors are the same size and do not needed to be started together.

#2 jOmega

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Posted 01 October 2010 - 03:32 PM

QUOTE (mike16 @ Oct 1 2010, 02:45 AM) <{POST_SNAPBACK}>
Is it possible to use the same liquid resistance starter to start more than one motor, say 3 and assuming all the motors are the same size and do not needed to be started together.




In a word . . . . . . . NO.




#3 amirogerami

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Posted 23 October 2010 - 11:08 AM

QUOTE (mike16 @ Oct 1 2010, 12:15 PM) <{POST_SNAPBACK}>
Is it possible to use the same liquid resistance starter to start more than one motor, say 3 and assuming all the motors are the same size and do not needed to be started together.


I think it would be possible, by using 3 contractors to close and open the circuit for each motor.

#4 jOmega

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Posted 23 October 2010 - 07:11 PM

QUOTE (amirogerami @ Oct 23 2010, 05:08 AM) <{POST_SNAPBACK}>
I think it would be possible, by using 3 contractors to close and open the circuit for each motor.



So let's see....... You think it would be OK to disconnect the ROTOR circuit of the running motor from the Liquid Resistance Starter, leaving the Rotor circuit... OPEN CIRCUITED ..... and then connecting the ROTOR circuit of a motor that is not running to the Liquid Resistance Starter and starting that motor ...... and then repeating that sequence to start a third motor .... ??????


Hmmmmmm. What's wrong with that picture ?????




#5 TonyS

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Posted 05 November 2010 - 08:52 AM

Temperature build up is going to be the problem. Most liquid starters are rated for maybe 4 starts per hour. I take it you’ll want to start the drives within a reasonably short time of each other, you’ll probably boil the electrolyte. Some starters can be fitted with forced cooling.
You would need 6 contactors.
What size are the motors?



#6 marke

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Posted 06 November 2010 - 09:18 PM

Hello mike16

I believe that it is technically feasible to use the one starter, but practically, it does not make sense to do so.

You would need additional contactors to bridge the rotors and to disconnect the rotors from the resistance starter. You would potentially have a major issue with heat as there is significant heat loss in the resistors for each start.

I expect that by the time you engineered a system that had sufficient control equipment and interlocks, and a starter capable of absorbing the energy for all motors, and made an allowance for cool down time in between each start, it would not really be commecially viable.

If you have a situation where the motors, once started, run for days and there is hours between each motor starting, then it may be viable.

Best regards,
Mark.




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