Controlling direction on VFD with analog signal

ferrari_man · Jun 17, 2009

Hello

I have a -10V to +10 V signal from a device which I would to control a VFD with. The problem is that I need it to work like this.
-10V full speed reverse (and -5V is 50%)
+10V full speed forward (and +5V is 50%)
0V stop.

We have a lot of teco t-verter E2 series, so if they were able to do it, it would be great.

An other solution was to control it like this (because I also have a 0 to 10V signal available)
But then it would have to be like this:
5V means stop
From 5 to 10 V the motor runs one way ( 10V is full speed one way)
From 5 to 0 V the motor runs the other way (0V is full speed the other way)

I like the first method best because if connection is lost then the motor just stops. (it not dangerous but still)

hope for a reply

Ferrari_man

cjd1965 · Jun 17, 2009

Hi
+/- 10V DC is standard for most drives, as this is a potentiometer signal level. I am unfamiliar with the make you have.You may need to configure the drive pamameters and/or dipswitchs.

The only other 'standard way' is to have digital signal to enable the reverse

Look in the manual or post a link here

leitmotif · Jun 18, 2009

ferrari_man said:
Hello

I have a -10V to +10 V signal from a device which I would to control a VFD with. The problem is that I need it to work like this.
-10V full speed reverse (and -5V is 50%)
+10V full speed forward (and +5V is 50%)
0V stop.

We have a lot of teco t-verter E2 series, so if they were able to do it, it would be great.

An other solution was to control it like this (because I also have a 0 to 10V signal available)
But then it would have to be like this:
5V means stop
From 5 to 10 V the motor runs one way ( 10V is full speed one way)
From 5 to 0 V the motor runs the other way (0V is full speed the other way)

I like the first method best because if connection is lost then the motor just stops. (it not dangerous but still) hope for a reply Ferrari_man

How are you going to "generate" ie what is source of -10 to + 10 V. While this sounds like a good idea I just dont feel all that confident it will work. When is the voltage close enough to zero to stop the unit +/- 0.1, or 0.01, or? I believe you will find that the potiontemeter or a variable input will only control speed proportional to voltage. Direction Fwd or Rev will be controlled by Fwd Rev inputs. Also how will you allow for E stop if needed / desired?

Dan Bentler

ferrari_man · Jun 18, 2009

Here is a link to the manual
http://www.teco.com.tw/sa/file/teco_product_en/45A9C328-60DE-4E03-A2DC-39429D924CB2/E2MANUALV09.pdf

I see point Dan and it has also been on my mind how accuate the voltage should be for stopping. I was maybe hoping to be able to set a min. voltage for the speed. I have seen this solution work on a servo drive but I have no infomation on how they did it.

( how fast can you change the direction with a digital signal, was just wondering )

ferrari_man · Jun 18, 2009

The only infomation I have from the system I have seen is:

Our systems offers:
• Plug and play
• Communication via serial port (RS485)

• Digital positioning system
• Fail safe brake system
• Std. analog input, 2 signals, ± 10 VDC each

• 110/220/380VAC 50/60 Hz

And it is SEW EuroDrive they use..

milldrone · Jun 18, 2009

ferrari_man,

Automation direct GS2 VFD's can do the 0-10V fwd - rev thing you are asking about. I'm sure others have this ability also.

After briefly parsing through the Teco manual It appears that what you want is beyond the Teco unit's ability. If you were to have a PLC interpret the 0-10V signal and hand off a FWD REV command in addition to the analog signal, this would be possible. A "dead band" could be programmed if there was a need to stop the motor at say 4.8 V to 5.2V.

ferrari_man · Jun 18, 2009

milldrone said:
Automation direct GS2 VFD's can do the 0-10V fwd - rev thing you are asking about. I'm sure others have this ability also.

Sound great. Any chance you could show me that this function is called. Maybe with a link to a manual. Then I could look if some of our VFD also have this function.

Ferrari_man

bernie_carlton · Jun 18, 2009

Here is the link to the manual - http://web2.automationdirect.com/static/manuals/gs2m/gs2m.html

Check 'Chapter 4' - specifically 'Example 3' on page 4-37

OkiePC · Jun 18, 2009

Rather than rely on the deadband in the drive analog input for "run enable", it would be wise to have a PLC controlled relay for enabling the speed control when it is not commanded to be zero. The last thing you want is for the driven motor to "have a fit" (jump forward for example) because of faulty analog wiring or induced noise on the signal. Then, in the PLC code, you can keep the enable relay energized if you need a quick response across the zero boundary or are still in fully automatic mode and only going to be stopped a couple of seconds, for example.

Still go ahead and program the deadband, and you can adjust it to avoid stall conditions which may exist at low frequencies on a V/Hz drive. but don't count on it 100% to keep the motor stopped.

Paul

Controls_Engineer79 · Jun 18, 2009

I'd have to agree with paul and Dan here, im pretty anal about saftey and i cant say i like the idea of having an analog signal controling direction- - ive always seen that as a speed control only - with relays or a plc having control of the "go/no go" part of the circuit.... mostly because when your dealing with analog theres always that SLIMEST of chances that you'll get noise - or a bad wire - - as paul notes - i mean sure say you install the system and everything works great - then 5 years from now, someone installs something else close by that generates nose on ur signal

then its "boom goes the Dynamite"

DickDV · Jun 18, 2009

The first analog control style is called bipolar 0-10V and is fairly common on mainstream brand drives. The second with zero speed at 5V is called joystick control and is somewhat less common. I do know that ABB drives have both capabilities but I am sure there are plenty of others.

Controlling direction on VFD with analog signal

ferrari_man

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