ABB ACS Inverter - Match control frequency to input frequency?

Hi all.

I have a project whereby multiple different motor arrangements need to be sync'd up. Normally this is no issue as we would use all DOL so the speed would vary with supply frequency or we use VFD's. This time, we will be mixing VFD's and DOL driven motors and I worry that if the supply frequency varies, the motors will be operating at different speeds. They are driving fixed flow hydraulic pumps so varying flow is not catastrophic, but undesirable.

There is no need for the VFD's in this application but the hardware is already installed so we want the VFD to vary the output frequency to match the input frequency. ABB ACS550 series.

Does anyone know if this is possible. I am not an EE and have limited experience/knowledge of these sorts of things.
 
Hi James.

Sorry if not clear but I want the VFD to follow the input frequency, not another inverter. The other motors are driven direct from mains.
 
Hi James.

Not sure how a schematic will help but here is more information.

Motor "A" with a DOL starter to mains power. Runs at 1485RPM @ 50Hz.
Motor "B" with ACS550 Inverter. Set to run at 1485RPM.

Both are connected to the same mains power supply. Mains power supply frequency may vary 49-51Hz for example.
Motor A will vary in speed but motor B will not. If however, I can get the VFD to adjust its speed based on the frequency of the mains power supply, problem solved and they will both operate at near enough the same speed.
 
Hi James.

Not sure how a schematic will help but here is more information.

Motor "A" with a DOL starter to mains power. Runs at 1485RPM @ 50Hz.
Motor "B" with ACS550 Inverter. Set to run at 1485RPM.

Both are connected to the same mains power supply. Mains power supply frequency may vary 49-51Hz for example.
Motor A will vary in speed but motor B will not. If however, I can get the VFD to adjust its speed based on the frequency of the mains power supply, problem solved and they will both operate at near enough the same speed.
Why Motor B will need an Inverter if it not varying in speed??
 
I am expecting variable frequencies because of the location of the site and the possibility of backup generator usage.

The other option is removing the inverters and replacing them with regular soft starters but as you can imagine, if there is a parameter change or some other trick that can save that hassle, it is my first choice.
 
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