Stop motor when torque/current limit, Schnieder Altivar 12

Hello!

We are having some trouble with pieces falling in between a chainbelt and destroying alot in the process.

The machine is using a Altivar 12 (ATV12H037M2) drive to control this motor.

I have activated the feature "Application Overload time delay".
But im a bit unsure if it works when you go with lower speed since this function compares with the rated motor current?

Most of the time it runs around 30-40hz.

Is there anything else/more you can do or are you limited with the Altivar?

JockeData said:

Hello!

We are having some trouble with pieces falling in between a chainbelt and destroying alot in the process.

The machine is using a Altivar 12 (ATV12H037M2) drive to control this motor.

I have activated the feature "Application Overload time delay".
But im a bit unsure if it works when you go with lower speed since this function compares with the rated motor current?

Most of the time it runs around 30-40hz.

Is there anything else/more you can do or are you limited with the Altivar?

Click to expand...

I'm not familiar with the 12's, but the function you need is also called, in the hardwired world, a "Shock Relay", for Di/Dt type of overload.

If the drive has a "shear pin" parameter that might do what you want. Failing that if you can set up the drive to output torque or current to a plc then you could code whatever overloads you wanted with that data.

jdbrandt said:

I'm not familiar with the 12's, but the function you need is also called, in the hardwired world, a "Shock Relay", for Di/Dt type of overload.

Click to expand...

This looks like the kind of thing im after! I will look into this. Thanks!

Mill_Control said:

If the drive has a "shear pin" parameter that might do what you want. Failing that if you can set up the drive to output torque or current to a plc then you could code whatever overloads you wanted with that data.

Click to expand...

Nope, cannot find something similar like that on this drive.

Mill_Control said:

If the drive has a "shear pin" parameter that might do what you want. Failing that if you can set up the drive to output torque or current to a plc then you could code whatever overloads you wanted with that data.

Click to expand...

AB Power flex 755, 753, 525.....problem solved...

The shear pin thing is Rockwell terminology for the same feature the OP is looking for.

Looking up the manual, I see 'Overtorque' detection. Modify parameters F615 to F619, pg132:

http://www2.schneider-electric.com/mwg-internal/de5fs23hu73ds/progress?id=6DcU95ElLBxm4cOQjWl1eyMa3sr5DKLhtG4tk3a7jEQ,

Not real familiar with Altivar 12 but if the output relay can do level detection, set the relay to pick up on top current or top torque level. Wire the NC contacts into the drive External Fault terminals to form a closed loop that opens on excess current or torque. If the drive doesn't have External Fault capability, wire it into the momentary stop button circuit so it forces a stop when the relay picks up.

AGill said:

Looking up the manual, I see 'Overtorque' detection. Modify parameters F615 to F619, pg132:

http://www2.schneider-electric.com/...=6DcU95ElLBxm4cOQjWl1eyMa3sr5DKLhtG4tk3a7jEQ,

Click to expand...

That link doesn't work, but I have a feeling it's not going to an ATV12 manual. There is no "F615" in an ATV12.

Yes, this would have been a lot easier in something like a PowerFlex 520 series, but you don't have one of those. It does appear this drive is designed more as a "pump and fan" drive, so it doesn't have the kind of features typically found in machine control applications. So yes, it appears as though the closest thing you have available to you on that drive is the "Application Overload" function in I_O_; tOL and LOC. But you are correct, it is only adjustable down to 70% of the programmed motor FLC, plus it will only work if the motor is NOT accelerating or decelerating, meaning it has to be "at set speed", whatever that is. So if you are at 30-40 Hz, and assuming it's a 60Hz motor, you are at 50-80% speed, meaning it's most likely that your running current may ALREADY be lower than the lowest setting of that feature. That would mean you are not going to be able to use that.

The only other thing you can possibly do, as per DickDV's suggestion, is to program the Relay R1 (assuming you are not using it for anything else) as "I threshold reached" (Code CtA), then go to parameter Ctd (Motor current threshold) and set it to a value that corresponds to what you want to indicate. The "Motor current threshold" parameter can be set from 0-150% of the DRIVE'S current rating. So you will need to do a little math, and a little experimentation to find the right level. Then wire the NC side of that relay in series with the Run command (there is no External Trip function available for the Digital Inputs on that drive either, as he had suggested), then wire the NO side of the relay to a pilot light telling the operator what's going on.

If you are already using relay R1 for something else, you could use the triac output, L01. But that is essentially the equivalent of a "Normally Open" contact, but logically, you need it to be like a Normally Closed, to OPEN on the "Motor current threshold" trip. You can apparently change the logic using the next parameter for LO1, called LOis (I think) to nEG, meaning Negative Logic (I assume). The manual is typical for a Schneider manual, translated from French so it makes it difficult to understand. {That's why I have always HATED Schneider drives as an integrator...}. That will not however leave you with any way to indicate why it has stopped. So it might mean running L01 to an external relay with a Form C contact and using like R1 above (in Positive Logic).

If you are using both R1 and LO1 for other important functions, I'm afraid you are SOL with that drive...

My apologies, I erroneously found the 212 manual.

After finding the correct manual, it does appear the 'Application Overload' is your best bet. But as jraef stated, the motor must be at steady state speed and the threshold is limited to 70% of nominal current, which either may limit this feature from working for you.

+1 to jraef for the research on using the threshold function.

Another consideration may be to use the current limit 2 function, CL2. It can be set all the way down to 0.25 of the rated current. Note this just limits the current.

There still needs to be a way to trigger the 2nd current limit ( LC2 assignment). Since the issue is occurring at 30-40Hz, there needs to be a sufficient rise in current/torque when pieces fall between the chainbelt and then the method jraef described may come into play. Confirm if the condition is detectable in terms of current/torque.


Otherwise, there is minimal differentiation in terms of current or torque from normal operation. In which case, might have to also consider mechanical ways to keep pieces from falling in- guarding and traps, if possible.. or consider functions in one of the more full featured Altivar's - 312 or 71.

Not sure how the 'shear pin' feature differentiates between normal operation and jam type conditions if the threshold is still within the normal operation range.

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You guys are awesome!

I will try out jraefs tip of connecting a relay to the output and trying to control the values there. We have decided that we should try and use the same speed all the time on the machine. So that we can have a stable stop function.

We would ofcourse like to make it 100% safe mechanically so the pieces wont fall down but this is a heat oven for shrinking plastic, so we need the space in the belt which is where the pieces get stuck. Luckily this only happens like once a month. But it still needs a solution because it destoys alot!

I will also give the shock relays a try on some test rig. Can be usefull in the future!

Thank you so much for all the input!