In need of solution

[boptrop]

Working on a pallet wrapper have a 4-20ma signal that I need to convert to 0-24V DC. Have DC power supply, 4-20 is generated by PLC. The device will need to be able to handle about .5A on the 0-24V. It will drive a clutch for pre stretch. Doesn't have to be full 24V output....but 15-16V would be nice.

If there is no device can some one chime in on how to do it with a POT? Or soemthing similar? Sorry don't know much about electronics..

Thanks,

 

[ptonsparky]

Working on a pallet wrapper have a 4-20ma signal that I need to convert to 0-24V DC. Have DC power supply, 4-20 is generated by PLC. The device will need to be able to handle about .5A on the 0-24V. It will drive a clutch for pre stretch. Doesn't have to be full 24V output....but 15-16V would be nice.

If there is no device can some one chime in on how to do it with a POT? Or soemthing similar? Sorry don't know much about electronics..

Thanks,

This may be a bit out of your skill level.

What is your budget for this project?

 

[boptrop]

LOL whats your price? I don't need the skill I need the device I described.
Im sure this can be done with the 24V power supply and a POT it no device exist.
I would have to do the research, which takes time and obviously it may be out of your skill level because you didn't post any meaningful solution.
along with the other 20+

 

[mgookin]

Working on a pallet wrapper have a 4-20ma signal that I need to convert to 0-24V DC. Have DC power supply, 4-20 is generated by PLC. The device will need to be able to handle about .5A on the 0-24V. It will drive a clutch for pre stretch. Doesn't have to be full 24V output....but 15-16V would be nice.

If there is no device can some one chime in on how to do it with a POT? Or soemthing similar? Sorry don't know much about electronics..

Thanks,

I've written a response 3 times now. This is tough with that information. It's not hard at all to do what you want to do but it does have to be done by someone who knows electronics.

Give us more info on that 4-20ma signal. How many volts and how many ma will it be? Is it active hi/lo or is it variable? Do you need different events to occur based on its magnitude?

And on the 0-24VDC well I can get you 0VDC real quick; here it is " ". Ok, joking aside, what voltage do you need? And what's the power on that?

I'm guessing you have a sensor kicking out a signal and from that signal you need to switch a relay with a DC coil to start or stop a process; correct? Been there done that.

Dial in that low power signal voltage & power, give us the DC you really want to use, then from that info go find a transistor to receive the low power signal and switch a leg of the circuit coming from the power supply. It'll cost you a dollar.

In the future please be more descriptive in the title of your thread. Everyone who posts here is looking for "a solution". Not trying to be rude; trying to help you.

With some more info we can probably get you on our way, even though this is a NEC forum with a primary objective of NEC compliance & building wiring systems.

 

[boptrop]

it needs to be proportional my friend......4ma=0v 20ma=24v simple
linear no high on low off bs

yea i know you guys specialize in arguing over gray areas...

the voltage is 0-24 DC as I stated and .5A as I stated do you need the power calculation from me???

I just cant stop here. I have been a master electrician for over 17 years and I expand what I do in the electrical field every day.
I don't need your criticism of what I ask....you can save that for your friends that think you are funny. I don't. Your questions posed to me are at most not worthy of my comments because if you read what I ask, you can figure out. So Don't be a jerk and keep your BS to your self. I have enough real world stuff to solve then to deal with some sarcastic troll.

 

[TommyO]

4-20 is generated by PLC.

Can the PLC be changed to generate a voltage (ex: different output module)

If not, I'd look at the PLC manufacturer to see if they have a ready-made adapter that does what you want.

It's possible to build one - but I think you're looking for something that if it breaks you can blame the manufacturer.

 

[Strahan]

it needs to be proportional my friend......4ma=0v 20ma=24v simple
linear no high on low off bs

yea i know you guys specialize in arguing over gray areas...

the voltage is 0-24 DC as I stated and .5A as I stated do you need the power calculation from me???

I just cant stop here. I have been a master electrician for over 17 years and I expand what I do in the electrical field every day.
I don't need your criticism of what I ask....you can save that for your friends that think you are funny. I don't. Your questions posed to me are at most not worthy of my comments because if you read what I ask, you can figure out. So Don't be a jerk and keep your BS to your self. I have enough real world stuff to solve then to deal with some sarcastic troll.

Wilkerson makes a unit that we use here at our plant which takes 0-10vdc and converts to 4-20ma. I know that's not exactly what you're looking for but I'm sure they make something that will work.

 

[Strahan]

Can the PLC be changed to generate a voltage (ex: different output module)

If not, I'd look at the PLC manufacturer to see if they have a ready-made adapter that does what you want.

It's possible to build one - but I think you're looking for something that if it breaks you can blame the manufacturer.

Good point if it's older AB stuff it can.

 

[boptrop]

I can do a 0-10V output on the plc or a 4-20ma, rebuilding from circuit board that no longer is available......

I have been looking for weeks....to no avail I guess the people that built the OEM circuit board had it custom made....i have yet to find a device that will do what I ask...

its OEM from Italy

American Tec support for the product is only knowledgeable with what the equipment was sold with....they don't do rebuilds..

 

[J.P.]

Wow.


Merry Christmas?

 

[boptrop]

yes merry x-mas. just don't start off with telling me that i can't solve it. It's man made it can be solved.

 

[TommyO]

I can do a 0-10V output on the plc or a 4-20ma

So I think a relay that can work on 10V would solve your problem.

 

[gar]

151223-2410 EST

boptrop:

There are several possibilities.

If you use the 4-20 mA output and need a linear proportional signal to drive the clutch, then use a current sensor followed by a voltage amplifier that cancels out the 4 mA to produce 0 V out with 4 mA in. Scale the amplifier gain to produce 24 V out with 20 mA in. Then use the 0 to 24 V to drive a power amplifier to power the clutch.

If you use the 0 to 10 V signal, then it is not necessary to remove the 4 mA offset.

0.5 A at 24 V is not a large signal to created.

I suspect that what you really want to control is the current to the clutch. This could be done by pulse width modulation of of your power supply.

Buying existing equipment to do the job is the most desirable. You might look for a progtammable DC power supply that can both source and sink current. This would effectively be the power amplifier to the clutch. If the power supply's output can be controlled from a voltage, then you only need the translator from 4-20 mA or 0-10 V.

A DC motor controller might be adapted to be your power amplifier.

Do some Internet searching for the above devices and see what is available.

If response time is not a major factor, then a reversed biased diode across the clutch could be used to eliminate a need for a sink capability. In this case a programmable voltage regulator solid-state device could control the voltage and therefore current to the clutch, or an emitter follower.

The response time of your system and the clutch time constant have a lot to do with how simple you can make the control.

Your clucth coil has a resistance of about 24/0.5 = 48 ohms. What is its inductance and how much does that vary as a function of current. By any chance is this a magnetic particle clutch.
http://www.warnerelectric.com/magnetic-particle-clutches-brakes.asp

I have a Placid Industries brake B35 24 V DC 9 W 35 #-in torque.
http://www.placidindustries.com/brakespecs.html

Do some searching and provide more information. Unfortunately some of the above responses have no idea what you want to do.

.

 

[ptonsparky]

Use a CLICK with an analog I/O. You set the parameters of how you want it to work with the 4-20 input.

I dont know if a small dc drive for a motor really cares if it is supplying a clutch or visa versa.

Have fun.

 

[Johnnybob]

If you have an allen bradley slc plc, you want a 1746 N04V or N04I analog module, don't know anything about italian made plc's.

 

[Johnnybob]

I dcan't seem to load a .pdf attachment. Anyway, I have an analog scaling chart I made in school, but it seems to be 8kb to big lol.
So 0-10v = 32767 binary counts. 20ma =6,384 binary counts. 4ma = 3277 counts. You need this to find the scaled value. so first, slope = Y max - Y min divided by X max - X min. then, since 4 ma doesn't correspond to 0 on the vector, you need the offset which is: Y max - (slope x X max)
Don't know if this helps, as I'm not sure what you nreally need. an allen-Bradley 1746-N04V analog module alows analog switching of an external 24v power supply.

Oh yeah! Merry Christmas!

 

[Aleman]

http://www.axiomatic.com/4-20ma-din-controller.pdf


Or something similar. I am assuming the clutch has variable tension etc. But the 4-20mA can't directly drive it.

I used to play around with electronics quite a bit. If was working on a DIY solution I would probably just use an op amp setup as a voltage follower,
then run the 4-20mA through a resistor to build a voltage input for the amp. Use the amp to drive the clutch.

 

[Smart $]

Are you adding the clutch, or is it already in place? If it is still in the design stage, I'd recommend going with a compressed-air clutch and using an I/P transducer.

 

[boptrop]

Thank you very much for all the replies they have been a good read for me...

-Gar...the clutches you have links to are similar to the one that is on the machine, I had a link to the MFG (which is Italian). I have searched the OEM drawings that I have and can't find it now.
-Time is not important in the reaction of the clutch as it will be manually input for pre-stretch by the user. I am not integrating it with a pid loop or combining it with a load cell- or anything of that nature.

-The inductance of the clutch, I can't tell you as I can't find the part specifications and I dont have the equipment to measure it....... Like I said before I had the manufactures web page up and It had some of those clutches pictured as u have in your links but I was unable to narrow it to the clutch that was on the machine...

The power supply that I have can't be manipulated, it powers the PLC and all the sensors, I had wanted to use it to power the output of the device. I would have to purchase another PS (one that is programmable). The OEM cabinet is getting very tight beacuse of the drives and , terminal strips PLC and other components and I don't have allot of room left (before failure most stuff was all in the circuit board). - So a DC motor controller is a great Idea but I don't think I have the room... and it will add to the heat in the cabinet...not in need of a fan yet!

"If response time is not a major factor, then a reversed biased diode across the clutch could be used to eliminate a need for a sink capability. In this case a programmable voltage regulator solid-state device could control the voltage and therefore current to the clutch, or an emitter follower."

This sounds interesting to me but I dont have the knowledge to build it (component selection and wiring)?

I can also program the PLC to output 0-20ma if that simplifies things.

What would be most helpful is a component list of what it would take to build what you describe in the quote above.

-Taking a look at the remaining posts.

ptonsparky...can you provide a link to this device? A small dc Drive sounds promising to me if I can get a small one (din rail mount preferred)...Is that what the CLICK is?

Johnybob...Its a Unitronics PLC....I didn't pick it, my boss imposed it on me. Next time I will use ab. This PLC has been a PIMA!
yes the PLC probably cant drive it, I cant find in the plcs specifications the load that can be imposed on the outputs so I don't want to risk burning it up. once this thing is done and tested at my location it will be shipped to another location several states away and I dont want to have to go out there and work on it much less look like a fool because of undersight.

-AlemanThe link you posted looks promising, but i don't like it as a connector arrangement. (if it were DIN rail mount!)...Gar...does this look like it will work?

http://www.axiomatic.com/4-20ma-din-controller.pdf

Again the lasts posts have been most helpfull and I appreciate the time spent. Please follow up if you can and have a great X-Mas

 

[boptrop]

See above Smart $
all-ready in place just rebuilding controls.