connecting a PLC to Inverter

Join Date
Nov 2013
Location
Port Talbot
Posts
3
Ive been asked to connect a small PLC monitoring system for a fish farm to control 2 inverter for air blowers. The alarm systems have been set up to activated outputs on the PLC and then in turn, activate the inverter drives. I have very little experience with connection PLC systems and would like some advice on how to connect

I have 6 positions for each relay output which are as follows
N/O
24v
C
I/O 1
N/C
0v

I have to connect in up to an ABB ACS150 Inverter drive.
Any help would be appreciated
 
With relay outputs, you have no way of generating an analog signal for speed (actually frequency). So, you will have to configure the drive to run at a constant speed whenever it is told to run.

The ACS150 has a frontmount potentiometer on it so I would configure it for terminal strip operation (Remote) but with the speed on the potentiometer. All you really need with that arrangement is a dry contact closure to run the drive. Open is Stop and closed is Run.

Connect the PLC contact with one side on the drive's 24VDC power terminal and the other side to the Run/Stop terminal, usually defaulted to DI1.
 
Plc connections

Thanks for you quick response. The inverter drive is set up using standard macro and using input DI1 & DI2 with the drive frequency set to specific points. I need to have 2 inputs into the inverter as normally it will run at 40Hz but when the low level alarm activates, a signal is sent to the Inverter to ramp up to 50Hz. The plc has been programmed for this purpose and I need to clarify what from the plc goes to where on the inverter. It get further complicated but when I know how to connect 1 drive, I can easily connect the remainder
 
With relay outputs, you have no way of generating an analog signal for speed (actually frequency). So, you will have to configure the drive to run at a constant speed whenever it is told to run.
You can set multiple constant speeds using only digital I/O on these drives. In the 'standard' and '3-wire' configurations, two of the DI/O are used to select from pre-set constant speeds (or front panel potentiometer). So you could, configure the preset speeds to use the potentiometer, and constant speeds of 40, 45, 50 Hz and use the PLC to select them. You can configure the drive for up to 8 speeds. Check out group 12 parameters Constant Speed.
 
What you may not be understanding here is that you have programming in your PLC, and you have programming in your drive. As far as the wiring goes, all you need to do it wire outputs of the PLC to inputs of the drive. The rest is done in programming in both devices. Since the drive is typically less flexible, I generally start with the recommended programming in the drive for a pre-set multiple speed application like this, it makes troubleshooting for the drive easier for the next poor schmuck that comes along after something breaks. Then once you establish that drive setup, write your PLC program to make that work for you with all of your other conditions.

In my experience, most small drives like this will have a setup available that will correspond to digital inputs 1 and 2, where input 1 is run in speed one, input 2 is run in speed 2. But it also could be that input 1 is just Run, then input 2 is selecting speed one if low (off), speed 2 if high (on).

YMMV
 
What type of PLC are you going to be using.

Essentially, all you have to do is hook up the outputs of the PLC to the inputs of the inverter and vice versa. (Assuming 24VDC outputs from PLC).

Looking at the defaults it would go something like this:
DI1 -- +24V to turn motor on / 0V to turn motor off
DI2 -- 0V to select forward (not used)
DI3 -- +24V to select 40Hz / 0V to select 50Hz
DI4 -- 0V to select 40Hz / +24V to select 50Hz
DI5 -- 0V to select standard acceleration (not used)

Normal operation would be DI1 and DI3 on. Alarm would turn DI3 off and DI4 on. DI2 (direction) and DI5 (ramp) probably don't need to be used.
 
It can be simpler than that. DI1 is Run/Stop as Timbert describes but set the VFD minimum frequency in Para. 1104 to 40hz. Then set Fixed Speed 1 (Para. 1202) to 50hz and connect your second switched 24V signal to DI3.

Now, with neither signal present, the motor does not run. With DI1 only present, the motor will run at 40hz. With DI1 and DI3 both present, the motor will run at 50hz. With DI3 only, the motor also does not run. So, DI1 selects Running or Not Running while DI3 selects 40 or 50hz.

I would suggest a jumper from AI1 to Analog Ground also to make sure no noise can get into AI1 and disturb the 40hz signal.
 
Output Signal

There are not any designated outputs on the drive itself. Is there a way to pull a signal from the drive to send to a PLC to determine if it is running or not? Is it possible to accomplish this using the NO or NC contacts on the drive? Thank you.
 
There are not any designated outputs on the drive itself. Is there a way to pull a signal from the drive to send to a PLC to determine if it is running or not? Is it possible to accomplish this using the NO or NC contacts on the drive? Thank you.
Are your sure? most drives have a error or "drive ok" output or contact which, most of the time nowadays, can be re-programmed to a lot of states, including "running"
 
I am using the 150, so that is probably what I need. I have looked through the manual and have not seen any parameters that will give a running bit indicator. I will give this a shot though. Thank you.
 
Well, correct me if I'm wrong, but the manual I linked to shows specifically that if you change the parameter 1401 from '1' to '2' then the N.O. contacts will indicate that the drive is 'Running: Start signal on, Run enable signal on, no active fault' - isn't that what your wanted.

You also mention in post #12 something about 'a running bit indicator'. The 1401 parameter change doesn't affect any 'bit' that could or may be accessed via some communication connection with the drive, just the N.O. contact which is what you asked for in post #9.
 
That is all correct. I guess I should have used different terminology than running bit indicator. I was really just looking for any way to show if the drive was running or not, and it seems like this parameter mentioned will do just that. So that should be good. Thank you.
 

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