# VFD .Two starters and thermal overloads ??



## BBQ (Nov 16, 2010)

Not an expert here but as far as I know you really do not want to put a starter on the output side of a drive. 

To run two motors from a single drive you would place just overload units on the load side and wire these OLs to shut the drive itself off.


Also if the two belts have different loads on them they will not always run the same speed even though they are run from a single drive.


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## the resistance (Jan 26, 2013)

I was thinking it could be possible if the drive has a 110 volt start input I could wire the coils of the starters in parrallel with the start input.The two motors are top and bottom conveyors for a bag smashing system that gets air out of bags . ineed to slow both conveyors equally.


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## BBQ (Nov 16, 2010)

the resistance said:


> I was thinking it could be possible if the drive has a 110 volt start input I could wire the coils of the starters in parrallel with the start input.


Why would you want to do that?

The VFD is your starter, all you need to do is provide individual overload protection for each motor. The OLs control contacts would be wired to tell the drive to shutdown.

Having a starter on the output of the drive is a bad idea, if one or both of the starters was to open while the drive was running it could fry the drive.


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## the resistance (Jan 26, 2013)

25,562 post on here BBQ makes you at least seem to have the potential to be a expert.lol


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## Safari (Jul 9, 2013)

BBQ said:


> Why would you want to do that?
> 
> The VFD is your starter, all you need to do is provide individual overload protection for each motor. The OLs control contacts would be wired to tell the drive to shutdown.
> 
> Having a starter on the output of the drive is a bad idea, if one or both of the starters was to open while the drive was running it could fry the drive.


deep fry thats the right word:laughing::laughing:
hey guys what type of drives are you using? mostly here we provide input mostly three phase to the drive,parametize the drive then connect the output directly to the motor without external overloads, we depend on the electronic overload of the drive.then of course provide the digital i/o and mostly one anolougue input (potentiometer) to suit their application.

but mostly as i read most threads in this forum mostly guys talk about the external overloads. ami missing something?


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## varmit (Apr 19, 2009)

If you install two motors on one VFD, on the load side of the drive install ONLY overloads for each motor- DO NOT INSTALL CONTACTORS. Wire the O/L contacts to the drive enable or stop. As long as this is not a high starting torque application, it should work fine.

Installing a contactor between a VFD and a motor is a drive killer.


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## BBQ (Nov 16, 2010)

the resistance said:


> 25,562 post on here BBQ makes you at least seem to have the potential to be a expert.lol


Potential to yes.

In reality I just don't shut up. :laughing:


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## the resistance (Jan 26, 2013)

With the starter coils in parrallel with the start input they would always open and close together, I was trying to be cost effective and economical by using existing components and only buying one drive but i think because of the setup its going to require two because the overloads arent capable of being wired into the drive inputs with existing components . I havent purchased the drive(s) yet just submitting a quote .Thanks


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## 8V71 (Dec 23, 2011)

BBQ said:


> In reality I just don't shut up. :laughing:


Case in point....103 posts in 31 minutes.  :jester:


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## JRaef (Mar 23, 2009)

the resistance said:


> With the starter coils in parrallel with the start input they would always open and close together, I was trying to be cost effective and economical by using existing components and only buying one drive but i think because of the setup its going to require two because the overloads arent capable of being wired into the drive inputs with existing components . I havent purchased the drive(s) yet just submitting a quote .Thanks


You are over thinking this. You do NOT need the "starters" any more, and in fact it is a bad bad bad idea to leave them in. Lose them, and replace them with low cost stand alone OL relays, then wire the OL relay aux contacts in series to the VFD control command circuit to shut it down if either motor overloads. You are trying hard to save money by leaving unacceptable components in the system, potentially risking the most expensive part of that installation, the VFD. Penny wise, pound foolish.


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## Safari (Jul 9, 2013)

varmit said:


> If you install two motors on one VFD, on the load side of the drive install ONLY overloads for each motor- DO NOT INSTALL CONTACTORS. Wire the O/L contacts to the drive enable or stop. As long as this is not a high starting torque application, it should work fine.
> 
> Installing a contactor between a VFD and a motor is a drive killer.


thanks varmit.am yet to wire two motors to one drive but i get the circuit you explained on how to wire an overload.thank you:thumbsup::thumbsup:


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## Jlarson (Jun 28, 2009)

Just get stand alone mounting bases for the OL relays and slap a load reactor on there and you are ready to go with your multi-motor plan.


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## JRaef (Mar 23, 2009)

Jlarson said:


> Just get stand alone mounting bases for the OL relays and slap a load reactor on there and you are ready to go with your multi-motor plan.


Good idea on the load reactor for multiple motors, I should have mentioned that. :thumbsup:


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## frenchelectrican (Mar 15, 2007)

Jlarson said:


> Just get stand alone mounting bases for the OL relays and slap a load reactor on there and you are ready to go with your multi-motor plan.


That what I did few time.

But let the OP know they will have to fine tune the VSD for little more variation on speed due some case it may get bounced feedback signal which I have ran into before and once I put the load reactor that useally stop them in track and all the mulit moteurs I set up ran much better.

Merci,
Marc


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## varmit (Apr 19, 2009)

frenchelectrican said:


> That what I did few time.
> 
> But let the OP know they will have to fine tune the VSD for little more variation on speed due some case it may get bounced feedback signal which I have ran into before and once I put the load reactor that useally stop them in track and all the mulit moteurs I set up ran much better.
> 
> ...


This especially true if the wire length is considerably different to each motor.


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