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#1 u_f_o_3k

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Posted 01 June 2006 - 04:29 PM

First of all, i like to say hi to all the forumers.i haf read some of ur thread n its really interesting.
I haf some question to ask, if u guys can help, i really appreaciate .

I am currently working in a frd Company, we r in the manufacturing. The company uses 200 single phase (230V)induction motors in its production operations.The motors deliver a constant torque of 0.8Nm while in operation. In order to cope with the increase output demand, we need extra 80 more similiar motors, however these additional motors might cause serious current overload to the factory electrical power installation, hence my Company, ask me , as a techician, whether i can tink of something to help..

The company does not intend to replace the power cables n installation gears sad.gif as the move will disrupt the tight factory production schedule n involve substantial cost. If the motor used each draws less than 1.5A, the current rating of the power cables will not be compromised..

i brain r tight up... i cant tink of anything other .....S.O.S

Ur guide is truly appreciated, thks..

#2 marke

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Posted 01 June 2006 - 07:41 PM

Hello u_f_o_3k

Welcome to the forum.

It is difficult to comment based on the information that you have provided, however with induction motors, you can reduce the current drawn by adding power factor correction at the motors.

We would need more information in order to comment on the viability of this as a potential solution for you.

Best regards,

#3 kens

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Posted 01 June 2006 - 10:15 PM

Hi, i would suggest that you need to look at three phase motors. With a torque requirement of .8Nm these are fractional motors so if the company is not willing to upgrade your supply then you need to go three phase which will be well under 1.5A each.
If you are stuck with single phase what is the motor speed requirement or what is the kW size? Will the supply handle the starting load of these additional motors?
Cheers
Ken
An expert is one who knows more and more about less and less until he knows absolutely everything about nothing

#4 u_f_o_3k

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Posted 02 June 2006 - 05:19 AM

1st of all, like to thks u guys for reply, am currently not at my site, till i check my motor rating,will let u guys know again, many thks smile.gif

#5 u_f_o_3k

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Posted 02 June 2006 - 10:31 AM

QUOTE(marke @ Jun 1 2006, 07:41 PM) View Post

Hello u_f_o_3k

Welcome to the forum.

It is difficult to comment based on the information that you have provided, however with induction motors, you can reduce the current drawn by adding power factor correction at the motors.

We would need more information in order to comment on the viability of this as a potential solution for you.

Best regards,

hello there Marke, nice knowing u, i haf go around n ask around frm frd's advice, he suggested using an auto trasnsformer to the xtra 80 motors, u said about adding power factor correction at the motors, is it all the motors haf to add a capacitors n mus the capacitors of a higher capacitance or jus add capacitors at the main power point?

THK u

#6 marke

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Posted 02 June 2006 - 09:36 PM

Hello u_f_0_3k

Adding an autotransformer can step the voltage up to overcome voltage drop problems, but if the cable is too small, it will over heat with the increase in current.
Power factor correction connected at each motor will reduce the reactive current and reduce the toal curent in the cable. This may or may not be enough to overcome your problem.

Best regards,

#7 u_f_o_3k

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Posted 03 June 2006 - 07:24 PM

QUOTE(marke @ Jun 2 2006, 09:36 PM) View Post

Hello u_f_0_3k

Adding an autotransformer can step the voltage up to overcome voltage drop problems, but if the cable is too small, it will over heat with the increase in current.
Power factor correction connected at each motor will reduce the reactive current and reduce the toal curent in the cable. This may or may not be enough to overcome your problem.

Best regards,

Thks for the info Marke, so by adding each pf correction at one motor will do the wonder, i'll let my bos know n c wats his opinion, oh ya, i've got a circuit of the single phase motor , will scan it n let u see when i free, thks again smile.gif

#8 mariomaggi

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Posted 04 June 2006 - 04:57 PM

Dear u_f_0_3k,

single-phase motors have usually a bad efficiency, compared to three-phase motors.
If your company calculates the energy saving, three-phase motors will be choosen.

Regards
Mario

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#9 u_f_o_3k

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Posted 05 June 2006 - 02:31 PM

QUOTE(mariomaggi @ Jun 4 2006, 04:57 PM) View Post

Dear u_f_0_3k,

single-phase motors have usually a bad efficiency, compared to three-phase motors.
If your company calculates the energy saving, three-phase motors will be choosen.

Regards
Mario

hello there mario, thks for the reply. smile.gif was tinking about marke suggestion past days, i got 200 motors,
mayb i'll add a better capacitors on the 1st 40 new pcs of motors, removed the 40 old motor n add new caps on it n gradually add up the leftover, i tink this would minimise the disruption of my company productivity .

For the cost side, i tink tat will haf to wait awhile b4 we could see the differences on the Bill..hehe
hmm.. other than improving the PF, is there other way to do it?





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