5HP reactors, 3/4HP motor

[ptonsparky]

Customer has 5 HP PowerFlex4 VFD complete with line and load reactors, enclosure, fans etc. He needs a reversing starter for a 3/4 hp. Will the reactors function well enough? Motor will be within 15 feet of the drive.

 

[Cow]

Where does a reversing starter come into play with a VFD? I think I need a one line diagram.

 

[ptonsparky]

If you have a vfd on the shelf, it is one heck of a lot cheaper than a new reversing starter, especially when the MCC is about 40 years old. And the MCC has a spare fused disconnect.

Has to do with the Run/Forward or the Run/Reverse thingys you get with them.

 

[tkb]

Why would you need a line and load reactor? I have only used line reactors.

 

[ptonsparky]

Why would you need a line and load reactor? I have only used line reactors.

The motor was 100 +-feet from the VFD in its past use. Not really worried about the 15', but if the load reactor is there already, why not. No drive cable is used, thwn & EMT.

 

[tkb]

The motor was 100 +-feet from the VFD in its past use. Not really worried about the 15', but if the load reactor is there already, why not. No drive cable is used, thwn & EMT.

Alrighty then. Works for me.

 

[Jraef]

So I still don't get the issue of the reversing starter if you have a VFD, because the VFD can be told to reverse the motor very simply, no contactors needed.

Are you replacing the VFD with a reversing starter and want to know if leaving the reactors in place is OK? If so, yes, but you will waste a little energy through the reactors.

Oh wait, are you wanting to use the over sized VFD instead of a reversing starter and want to know if having the line and load reactors on a smaller motor is OK? Then yes again, but same issue.

Generaly it were a vector drive, you couldn't use a 5HP drive on a 3/4HP motor because it's too small; most vector drives will have a lower limit of 50% of the drive rating, because for the vector to work it needs accurate current information and below 50% rating the measurement error gets in the way. But the PF4 is not a vector drive, so it doesn't care.

 

[ptonsparky]

So I still don't get the issue of the reversing starter if you have a VFD, because the VFD can be told to reverse the motor very simply, no contactors needed.

Are you replacing the VFD with a reversing starter and want to know if leaving the reactors in place is OK? If so, yes, but you will waste a little energy through the reactors.

Oh wait, are you wanting to use the over sized VFD instead of a reversing starter and want to know if having the line and load reactors on a smaller motor is OK? Then yes again, but same issue.

Generaly it were a vector drive, you couldn't use a 5HP drive on a 3/4HP motor because it's too small; most vector drives will have a lower limit of 50% of the drive rating, because for the vector to work it needs accurate current information and below 50% rating the measurement error gets in the way. But the PF4 is not a vector drive, so it doesn't care.

I thought I was clear, but I guess not. My help look at me with glazed eyes often enough so I should know better.

Wasting a bit of energy doesn't bother me and I don't think there will be a reflective wave problem @ 15' to the motor but if it won't hurt, I would just leave it in place.