adccommunitymod (AutomationDirect) asked a question.
GS1 drive index conveyor
Created Date: April 26,2006
Created By: dfleonard
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Has anyone set up this drive to index a conveyor? The positioning of the product needs to be comparable to a DC drive and motor. I am looking to use the 1/4hp drive with a 1/4hp motor. Basically looking to replace a like DC drive Hp set up. Would I just need to keep the motor extra cool? Or would a vector drive be the only way?
Created Date: November 10,2006
Created by: dfleonard
Has anyone ever done this (use a GS1 on a indexing conveyor)? How much is too much start and stop on the GS1 drive? 40 ppms?
It sounds simple I was just told by a competitive "salesman " that the GS1 will burn up if you start and stop it too often.
Created Date: August 24,2007
Created by: dfleonard
Anyone got any input on this? Suggestions? is a GS2 a better fit?
Do you need more information perhaps?
The conveyor is currently powered by a 1/4hp 2500rpm DC motor that has a 10:1 ratio gearbox. Rpm output is 250. The motor is stopped and started a maximum 40 times per minute.
Created Date: August 24,2007
Created by: milldrone
dfleonard,
I don't know if I can help but I have a few questions. Warning: some of your answers may lead to other questions.
1. Is the plan to reuse the gearbox?
2. What rpm does the existing DC motor run at now?
3. Can you get an amp reading on the existing drive?
4. What supply voltage are you now using? what supply voltage would you like to use?
5. Indexing stops aside, does the conveyor change speeds as in variable? If it does how slow? (motor rpm)
6. Just for general info. Are there any maintenance issues with the DC drive like excessive brush wear?
7. Is there a brake?
8. What sort of control do you now use on the DC drive?
Created Date: August 24,2007
Created by: Tech Guy
One of our customers did an indexing table with a GS2 that was very similar to this. It worked fine. You might need braking resistors and/or a gearbox depending on the inertia that the conveyor has.
Milldrones questions are good starters as to whether it will be a good fit for you or not.
Created Date: August 24,2007
Created by: dfleonard
Thanks for the responses.
Presently The PLC, thru an analog module, provides an 0-10VDC to the DC drive's isolated input module.
Yes, this will be variable speed.
As far as the Gear box ratio. Its still open. I will try to keep the AC (inverter ready) motor going at a decent rpm at the conveyors minimum speed(which I can set). Most people want to run fast though.
My biggest concern is starting and stopping at a Maximim cycle rate of 40cycles per minute. Can the GS1 handle this rate. Or is the GS2 better equipped. Should I over size the drive? Say a 1/2hp drive with a 1/4hp motor.
I can bench test several setups at various speeds and watch motor temps and driver problems.
But I am trying to get the best bet (theorectical) "for the money " scenario would be, before spending the cash.
From what I have researched Vector drives would do the bestr but are significantly more costly and would eatup any money saved by eliminating the PLC's analog output module.
I plan to control the speed via modbus communication available on my HMI.
Thanks in advance for advice.
Created Date: August 24,2007
Created by: krak
have you considered a clutch set up? perhap between the motor and gear box?
Created Date: August 24,2007
Created by: milldrone
dfleonard,
Should I over size the drive? Say a 1/2hp drive with a 1/4hp motor.
I would not even blink on this one. Go with the 1/2 HP drive. Given the stop start nature of the application.
My biggest concern is starting and stopping at a Maximim cycle rate of 40cycles per minute.
Believe it or not this is where a VFD really shines. Because the motor is "on the ramp " during acceleration it doesn't get hit with the 600% of full load amps when it's near zero speed. The large current makes a lot of heat very fast in the motor. Most of the time a general comparison can be made HP for HP when talking AC vs DC.
Can the GS1 handle this rate. Or is the GS2 better equipped
I think all of the GS2 units have dynamic braking as standard and the GS1 units do not. I cannot even see any brake terminals in the catalog for the GS1. Automation direct would be a better source of info in the GS1 to GS2 comparison department. I have no hands on experience with the GS1. But my gut feel is that because of the dynamic braking issue the GS2 would be the way to go.
Presently The PLC, thru an analog module, provides an 0-10VDC to the DC drive's isolated input module.
money saved by eliminating the PLC's analog output module. I plan to control the speed via modbus communication available on my HMI.
If I'm interpreting your comments correctly this can be done but he HMI needs to be the master. You will have to hard wire the start and stop commands from the plc to the drive. Unless your HMI is capable of this.
Some more questions.
1. You mention "indexing " do you mean stopping in an exact position like 47 degrees of shaft rotation or similar?
2. What rpm does the existing DC motor run at now?
3. Can you get an amp reading on the existing drive?
4. Presently is your analog output module the only control on the DC drive?
Created Date: August 24,2007
Created by: dfleonard
1. You mention "indexing " do you mean stopping in an exact position like 47 degrees of shaft rotation or similar?
Presently I am stopping a product on the conveyor with in a given area. The package does not have to stop on a dime, it just needs stop at a consistent place. Kind of quickly lets say .1 second ramp down time.
2. What rpm does the existing DC motor run at now?
About 1750rpm @ max speed and 800 rpm @ minmum speed. This is the motor speed. The gearbox is a 10:1 reduction.
3. Can you get an amp reading on the existing drive?
The amp reading on the output of the existing DC drive is approximate 1.5A at full speed unloaded (as in no product on the conveyor). Heaviest product range would be similar to two reems of copy paper. So we are not talking huge loads.
4. Presently is your analog output module the only control on the DC drive? No I use a contact closure from the PLC to activate or deactivate the inhibit terminals of the DC drive.
If I'm interpreting your comments correctly this can be done but he HMI needs to be the master. The HMI can be set up as a master modbus terminal.
I agree the GS2 with dynamic braking sounds like the way to go. But I may experiment with GS1 just to see.
Created Date: August 24,2007
Created by: dfleonard
Originally posted by krak:
have you considered a clutch set up? perhap between the motor and gear box?
That is a possibilty depending on the costs
Created Date: August 24,2007
Created by: milldrone
dfleonard,
The amp reading on the output of the existing DC drive is approximate 1.5A at full speed
I should have also asked for voltage.
Is this amp reading during steady run? What we need is the peak amps during acceleration.
Another question. Does the existing DC drive regen? Can you read any amps as the motor is stopping? Not while it's stopped but as it's trying to stop. What I'm trying to get a feel for is how fast the conveyor stops on it's own without any help from the motor. If the motor needs to slow the conveyor down to get the cycles per minute then we have to have dynamic braking. DC injection braking would not work.
Inhibit contact ahhh! Is this a Dart brand controller?
Hey maybe Tech Guy will share some of the specifics of the job he mentioned.