Hi Sir

[Lancie1]

Crying Baby,

There must be some language difficulty here. I have read all the messages, and looked at the whole picture.

I think that most of your helpers are so far above your level of knowledge that there is a great problem with communication and understanding.

Here is my opinion. You do not know that VFD's (Variable Frequency Drives) are made to take an analog signal input from a Programmable Logic Controller and convert that signal to a variable Alternating Current voltage and frequency, that is commonly used to control an AC motor. VFD's can do this with no modifications and no changes. That is why everyone is having trouble to know how your professor considers this to be a challenge. I suppose that he does. If so, then your problems are solved!

1. Buy a low-cost Variable Frequency motor drive, with a 0-10 volt DC signal input. This is a standard type. Most of them also have 4 to 20 miliampere inputs also.

2. Get an analog output module for your PLC. This will produce a varying signal that is used to tell the VFD how fast to run the motor.

3. Connect the terminals of the analog output module to your VFD signal input terminals.

4. Connect at least three On/Off PLC output terminals to the Start, Stop, Forward, and Reverse control terminals of the Variable Frequency Drive.

4. Write a program that will Run Forward, Stop, Run Reverse, and change the speed of the motor, using the variable speed drive.

5. Add any other things that your professor requires for you to get a passing grade!

That is it; so simple when you condense it down to the basic things.

 

[crying_baby]

Crying Baby,

There must be some language difficulty here. I have read all the messages, and looked at the whole picture.

I think that most of your helpers are so far above your level of knowledge that there is a great problem with communication and understanding.

Here is my opinion. You do not know that VFD's (Variable Frequency Drives) are made to take an analog signal input from a Programmable Logic Controller and convert that signal to a variable Alternating Current voltage and frequency, that is commonly used to control an AC motor. VFD's can do this with no modifications and no changes. That is why everyone is having trouble to know how your professor considers this to be a challenge. I suppose that he does. If so, then your problems are solved!

1. Buy a low-cost Variable Frequency motor drive, with a 0-10 volt DC signal input. This is a standard type. Most of them also have 4 to 20 miliampere inputs also.

2. Get an analog output module for your PLC. This will produce a varying signal that is used to tell the VFD how fast to run the motor.

3. Connect the terminals of the analog output module to your VFD signal input terminals.

4. Connect at least three On/Off PLC output terminals to the Start, Stop, Forward, and Reverse control terminals of the Variable Frequency Drive.

4. Write a program that will Run Forward, Stop, Run Reverse, and change the speed of the motor, using the variable speed drive.

5. Add any other things that your professor requires for you to get a passing grade!

That is it; so simple when you condense it down to the basic things.

thank you so much lancie1.
i was at the verge of losing hope.

 

[Registered]

I would like to say this has been an interesting thread to follow.

I would like to say that it would work.

I will say that I have been drinking.

I may be posting under the influence.

I would like to say the "professor" has a grip on things.

I would like to take a nap now.

I think that some of the "top" people on this site, many who have posted on this thread, some who have not, could do this hair-brained idea. However, I think that if they HAD the TIME, and HAD the MONEY to through away, that thay ARE SMART enough NOT to do it.

I think when I wake up, this thread will not be here, that it was just a bad dream.

 

[rsdoran]

i need a beer...wait i am drinking one!

 

[CaseyK]

Ron:

One beer is not enough, neither is two!

I know I haven't had enough yet, but then, I haven't had my nap either.

After he has a few hundred hours in this, He may catch on, and maybe not.

On the other hand, I hate to see the sacrifice of a GE Micro, but sometimes, ya just gotta.....

Maybe things will be better in the morning, and maybe not.

best regards.....casey

 

[Colossalnut]

Love this one!
Many decades ago I wanted to make an amplifier so I attached a 120v line to a speaker!!!! Hahahahahahaaa......It DID amplify for about a milisecond! What fun we have in learning......

 

[Fred Floggle]

Wow Just how far can the thread wander ? What is frightening is the lack of knowledge exhibited by some in the method of operation of AC drive systems - there are a few little soldiers who need to go back to first principles and read just how a simple AC drive works

 

[CaseyK]

As I wander through this post, I think I have finally figured out what he is after...

it is noload. he professor is interested in only to c the PLC able to control the motion of the ac motor,
the motion r start, stop, forward, reverse, and brake, and possibly crude position control using open loop no feedback

the professor, wants to c that, PLC can actually control the ac3phasemotor, compared to the conventional, connect to supply and turn the switch on that kind of stuff.

to connect it to another load , will be out of the scope of the proposal.

He seems to want a vaiable speed reversable micro fractional horsepower 3 phase DC servo motor demo display.

Heck, thats easy. (9 volt battery with a pot and a dpdt center off switch. Slightly more complicated with a plc.

 

[elevmike]

Casey,

Hows them MGDs hold'n up?

 

[CaseyK]

I'm dry, have 3 Miller Lite ponies.
Bob's out, all he has left is Foster's and Guiness.
My son had a table full of MGD Lite dead injuns left over from last night.

Road Trip!

Is there a ferry from Milwaukee to D'troit? Figure if I go to Milwaukee, they'll give me beer to leave!

So, how's Dr. Mike been?

Did the poor guy on the delleted thread figureout the meaning off life, and find pops a girlfriend?

 

[DonsDaMan]

You know, Casey, re-reading the post... He needs only a reversing contactor and some kind of positioning without feedback. Dunno how he's going to do the last, really... the "no feedback" part.

Nowhere does it state "speed control." Just forward, reverse, stop, and some kind of crude positioning.

Nothing about changing the speed.

I hope C_B is not trying to do the same thing. Like I said, I'd like to see what the professor actually asked for.

 

[CaseyK]

If there is a PLC god, this project WILL be built, and there will be a thread, similar to "Learning By Doing", so we will all be able to follow it.

I think the variable speed control is a must, to get the positioning down. And maybe not.

Heck, if he doesn't need much speed, let's go to Radio Shack and get him a TV rotor!

Wait, that's too simple.

But then...

ok. forget about , the pwm and inverters,

and

i try to control the motion of the 3phase acmotor . that is my bottomline.

It is beyond me, Dan.

I think DickDV needs to get in THE final word, then close the thread.

best regards.....casey

 

[DonsDaMan]

Wait! I've got it!

Put the Motor on a car. Use one of the multiple stop light programs around this site to control its motion.

Problem solved.

 

[CaseyK]

Wait! I've got it!

Put the Motor on a car. Use one of the multiple stop light programs around this site to control its motion.

Problem solved.

P E R F E C T !

Makes perfect sense to me.

and I wrote:

It is beyond me, Dan.

Sorry about that DON! Even with the new glasses, I still don't see so well.

Now, to find a use for those washing machine programs!

take care.....casey

 

[rsdoran]

His objective can be done in many ways with the GE micro, the simplest being use reversing contactors. This would allow stop, start and reverse but no braking but that too could be accomplish with a little reading. I may have some that I will give if it will help...along with a wiring diagram.

Somewhere I offered info on reversible solid state relays...forgot if it was this thread or another now.

Using the GE micro and PWM to drive an inverter circuit is impossible and impractical. I didnt see until late that a GE micro was mentioned.

Could something be developed to drive an inverter? YES, but crying baby needs to read alot more.

MGD? I like my beer darker than fluids left in the bathroom!