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Signode
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Join Date: Aug 2007
Location: Lahore
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Running an AC Motor in Idle Mode

02/04/2009 3:04 AM

Dear Friends;

As we know if a flexo printing machine stops, the glue roll or ink roll run in idle mode (25-50rpm) for preventing any glue/ink jam on roll and when M/C re-stars, they run in-line with machine. I wan to know the best practice of our colleagues for programming an inverter in such a condition for running the motor in idle mode when speed ref drops at 0V and where we don't have any access with PLC to change in the program and set a min speed value.

Kindly help

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PWSlack
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#1

Re: Best practice for running an AC motor in idle mode.

02/04/2009 3:43 AM

Simply program the inverter to run at a minimum speed of 25-50rpm. Nearly all inverters have this facility these days. Of course, the frequency needed for this has to be determined from the local mains frequency and the selected motor's maximum speed.

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sb
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#2
In reply to #1

Re: Best practice for running an AC motor in idle mode.

02/04/2009 5:07 AM

What is your usual speed (no Idea at all about the application ) but if it is too different from the idle speed- usage of inverters have to be carefully done since line reluctances will drop down like anything and the current may shoot up.

I will prefer a gear shifter in these conditions. mechanical, hydraulic or any other type.

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Signode
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#3

Re: Running an AC Motor in Idle Mode

02/04/2009 11:09 PM

OK.

If I set a value (for example 5HZ) in Min Freq parameter, it fulfills my requirement as when SP Ref < 1V, motor run at 5HZ but the scale (1V = 5HZ) distorts. I have inverter 1305-3HP Allen Bradley.

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tooz
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Australia - Member - New Member Engineering Fields - Electrical Engineering - New Member Engineering Fields - Electromechanical Engineering - New Member

Join Date: Jan 2008
Location: Mount Gambier, South Australia
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#4

Re: Running an AC Motor in Idle Mode

02/05/2009 12:57 AM

Hi,

We probably need a little more info to give you a good answer. With your print/ink rolls, do they have a seperate drive? The machine I worked on was a flexopraphic printer, with 4 print heads around a main drum, with a mechanical gear to the drum.

If you have a seperate drive, it would be easy on most VSD's to use a digital input on the drive to switch the drive reference from the common reference to run at a fixed preset speed when unloaded, and not have to do any PLC programming.

Trevor.

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double_j_b
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#5

Re: Running an AC Motor in Idle Mode

02/05/2009 9:07 AM

What kind of Press do you have and what is the current drive setup on the machine.

i.e. clutch drive from press and from idle motor of the anilox or are you running a servo driven machine?

Lots of questions to be answered before proper assistance can be given.

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