[BBMNet]

Hello.

What you take as a second transformer is a line filter. It is used to minimize the amount of electric "noise" generated at the switching transistors from being fed back into the power lines. Some disk capacitors might also be connected to it.

For some VFDs that filter is an optional external component and some already include it as in the one you have. There are even some line filters that are connected between the VFDs and the motors they drive. Their function in this case is to protect the switching transistors from the EMF generated at the motor in particular when slowing down as the motors work as generators at least for a moment. That is also the reason why some VFDs also use external power resistors. They help dissipate the excess charge fed back by the motors.

I don´t know what type of filter your VFD has. The VFD to line or the VFD to motor but most probably the first one.

In reference to its use you should consider that the actual power obtainable from the VFD must be derated when connected to two lines instead of three. To be on the safe side estimate an actual loose of at least 40%. If your drive is a 3 HP unit you should drive a motor no bigger than 1.8 HP.

I hope this clears up some things.

I noticed that you already got ideas on how to connect this drive. I hope it al works well

Best regards.

[Jim Dawson]

Hello.

What you take as a second transformer is a line filter. It is used to minimize the amount of electric "noise" generated at the switching transistors from being fed back into the power lines. Some disk capacitors might also be connected to it.

For some VFDs that filter is an optional external component and some already include it as in the one you have. There are even some line filters that are connected between the VFDs and the motors they drive. Their function in this case is to protect the switching transistors from the EMF generated at the motor in particular when slowing down as the motors work as generators at least for a moment. That is also the reason why some VFDs also use external power resistors. They help dissipate the excess charge fed back by the motors.

I don´t know what type of filter your VFD has. The VFD to line or the VFD to motor but most probably the first one.

That is not correct. There was no VFD in the original system. There is no line filter supplied with the VFD, it is a separate item. The second large transformer in the pictures is the power transformer for the servo drives.

In reference to its use you should consider that the actual power obtainable from the VFD must be derated when connected to two lines instead of three. To be on the safe side estimate an actual loose of at least 40%. If your drive is a 3 HP unit you should drive a motor no bigger than 1.8 HP.

Derating is only done in the case that the VFD is not rated for single phase input. If the VFD is rated for single phase input, it will drive a motor at it full rated power on single phase.

[mactec54]

That is not correct. There was no VFD in the original system. There is no line filter supplied with the VFD, it is a separate item. The second large transformer in the pictures is the power transformer for the servo drives.



Derating is only done in the case that the VFD is not rated for single phase input. If the VFD is rated for single phase input, it will drive a motor at it full rated power on single phase.

You would have a hard time finding a single phase rated VFD Drive to run a machine that size which would need a minimum of a 5Hp VFD Drive, so derating is always a norm above 2Hp