# VFD control push button issue



## earle13 (Jun 17, 2015)

Hi guys,

I have 2x Schneider ATV312 VFD's ive just installed. 

They were working normally from the local keypad on the drive. I then added 1x n/o start button and 1x n/c stop button and pot's to each drive, which is very basic.

I followed the logic input drawing provided with the drives and they aren't working. I have a supply wire coming from the 24v terminal on the VFD, which goes to the start of the start button them loops across to the start of the stop button as to supply both buttons. I then have a wire going from the end of the start button to terminal LI3 as it shows on their drawing, then a wire going from the end of the stop button to terminal LI2. 

I assumed these would be wired in as temp push button to trigger the logic inputs and the drive would stop or start as to the assignment of the internal inputs. 
I changed the input parameter to 3 wire and none of the buttons do anything. I then changed it to 2 wire and my stop button starts the drive but my start button doesn't stop it (confusing but i thought they might have been reversed. 

This has confused me a little as i thought the inputs would just need to be triggered momentarily with the 24v.

If anyone understands what im talking about or the issue/solution i would definitely appreciate some feed back. As an Electrician i am still learning everyday.


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## MDShunk (Jan 7, 2007)

Your stop button needs to be a normally closed contact. I think to terminal LI1. That's the most common mistake.

Is your pot properly wired and turned up? Did you set the parameter to look at analog input 1 for the speed reference?


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## earle13 (Jun 17, 2015)

Thanks Stop button is a N/O contact. 

And yes the pot's are tested and working


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## earle13 (Jun 17, 2015)

Sorry i wasn't watching what i was typing. 

My stop button has a n/c contact. N/o for the start


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## MDShunk (Jan 7, 2007)

I just re-read what you wrote, and I'm about 99% sure that stop goes on LI1 and start on LI2. I'm not even sure what LI3 is used for. Probably configurable or maybe forward/reverse. Double check your inputs are on the right terminals.


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## earle13 (Jun 17, 2015)

Sorry again, you're correct. 

My stop is going to li1 and my start to li2, im not using li3 as i don't need to reverse.


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## MDShunk (Jan 7, 2007)

So if you're using the right contacts and you've got stuff wired on the right terminals, that leaves parameters. Those drive suck to program, in my opinion. I think the only two you need to change would be the speed reference to come from analog input AI1 and the I/O command to be 3-wire. Oh... some drives have a little dip switch or maybe a shorting block jumper that you have to put to something like "source" to use the drive's internal 24v power for the control stuff instead of supplying your own.


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## ponyboy (Nov 18, 2012)

Yeah you should be bringing power out of the +24 terminal on the drive, through your push buttons, and back to the proper drive terminal LI1 I think. There's probably a jumper on the +24 terminal but you gotta just jam your conductor in with it. 


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## micromind (Aug 11, 2007)

In addition to the above........

Is the control scheme set for source logic or sink? Source is like switching the hot, sink is like switching the neutral. Use source, it's easier to understand. This is usually set by either dip switches or jumpers, not programming. 

Once in a while, I'll have an issue with the pushbuttons. Sometimes (rarely), the PB cannot handle the low current of the drives inputs. I've actually measured 24DC across closed contacts of new PBs and relays. The solution is to get low-current contact blocks. 

I don't know about Square D, but a lot of drives have an 'enable' terminal that needs to be connected. This is often done with a factory installed jumper, but not always.


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## earle13 (Jun 17, 2015)

Thank you mate for the help.

The dip switch is set to SINK, and i am getting 24v across the N/C contact block which confused the hell out of me haha


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## earle13 (Jun 17, 2015)

Ok so i bridged out LI1 with the 24v terminal on the 3 wire setting and it did nothing. Then tried it on the 2 wire setting and the enable works then i can ramp the motor up with the pot. 

Im guessing im missing something in regards to the 3 wire control.


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## MDShunk (Jan 7, 2007)

Hang on a sec... did you put the switch to SOURCE yet?


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## earle13 (Jun 17, 2015)

Yep, dip switch has been on source the whole time.


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## earle13 (Jun 17, 2015)

Ok i got it, played with some of the parameters and now 3 wire control is working.

Thank you for all the input.


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