Line reactors need

[g.mccormick]

We are building an air flow stand that has ABB vfd running a 40hp inverter duty motor. The motor is coupled to a blower.

The panel for the high AC is going to be extremely tight with having two line reactors on it (incoming to drive and load side of the drive). I'm wondering if just getting rid of the reactors will be ok.

The output from the drive is only going to be 5 to 6ft to the motor.

What does everyone think?

 

[bce123]

I would use one the line side

 

[dmargineau]

The line reactor (obviously connected to the Line Side of the VFD) is installed for the protection of the (upstream) supply power of the drive, preventing VFD generated non-linear oscillations to reach other devices connected to (fed by) the same transformer; I would not recommend the removal of the line reactor since ABB VFDs are notorious for "pushing" self-generated waveforms within the line circuits.
The load reactor could be removed within certain conditions, one of which could be the short field wiring run; if you decide to remove the load reactor make sure the motor feed wiring is exactly conforming to the ABB specifications.

 

[Lancie1]

The line reactor (obviously connected to the Line Side of the VFD) is installed for the protection of the (upstream) supply power of the drive,...

Because this reactor protects the upstream equipment, there is not much arguement for it having to be located near the VFD (specially if you use shielded VFD cable or metal conduit). It could be moved farther upstream to a less-crowded area. All you need is a fuse, breaker, or switch on that line so that you can connect the reactor at that point.

 

[g.mccormick]

Thanks guys, I was able to shift some stuff around and get the reactors on the panel nicely. I'm stuck with only using 36x36 enclosure, it gets full quickly.

Thanks again.

 

[DickDV]

At 40hp, you have either an ACS800 or ACS550. Both have internal 3% input reactors or the equivalent built in standard. An additional reactor will only lead to excessive voltage drops under heavy loads. An MG1P31 inverter duty motor 6 feet from the drive most definitely does not need a reactor.

 

[bce123]

ABB so that's what the extra b is for line reactor? I always use on with my AB power flexes

 

[Highland Controls]

For the ACS550 I believe that the line reactors are only in the R5-R8 frame sizes. R1-R4 frames have a DC choke instead. 40HP could either be an R4 or R5, depending voltage, etc.

 

[g.mccormick]

Its the ACS550 R4 frame. I did not spec the drive or reactors (I originally wanted to use Automation Direct). Another guy worked with the electrical supply house to spec the drive and reactors. Maybe I need to make a call to ABB.

 

[g.mccormick]

I looked at the Technical manual, built in AC reactor is only in R8 size.

 

[Highland Controls]

ABB makes very good drives, so I think you have the right hardware. ABB is always going to officially say you need a line reactor, and always recommend a load reactor. You might be able to get away without the load reactor, but I would use a grounding brush for the motor shaft.

 

[Highland Controls]

I think it depends on where you read the specs, but it should be R5-R8 having a 3% reactor.

 

[g.mccormick]

I read the specs from the ABB tech manual. My drive is an ACS550 R4. No built in reactor.

Its all a moot point now, as I was able to get everything mounted nicely in the panel. No issues anymore.

New question. I am going to attempt to put an acrylic panel over the 480V in this panel. Has anyone had any luck trying to bend acrylic using a heat gun to heat it up? I going to try this and if anyone has any tricks I would appreciate them.

Thanks

 

[Tom Jenkins]

Dick DV is the expert, so I'd follow his recommendations. However, I can't resist putting in my two cents.

Drive harmonics is one of the least understood aspects of VFD applications, and is the lubricant of choice for more snake oil salesmen than any other aspect of the field.

For most applications the manufacturer's standard line reactor is sufficient. A load reactor is generally only necessary if you have long wire length between the VFD and the motor, and the definition of "long" varies with manufacturere and motor size and voltage. I have rarely used load ractors, and only after having a trusted tech guy with a respected manufacturer (like ABB) look at my specific application. I have occasionally used reflective wave trap to mitigate dV/dt insulation impacts on existing motors.

Brushes to inhibit bearing fluting are not a bad idea, but I have to confess I've only used them on one project, a medium voltage drive, and I have had only one bearing fluting incident in the hundreds of VFD applications I've worked with.

One word to describe the most important aspect of harmonics control: GOOD GROUNDING. (OK, that's two words - I wanted to see if you were paying attention!) At the motor, at the VFD, at the control - nothing else works right if the grounding is poor.

Dick, please correct any mistakes in the above.

 

[DickDV]

No mistakes, Tom. But, the ACS550 in the smaller sizes does have a DC choke instead of a line reactor. This choke is the functional equivalent of an input reactor for harmonic suppression purposes and does not drop as much voltage. Still no reasonable need for an input reactor in the application we are discussing.

One other comment about reactors. THEY DROP VOLTAGE UP TO THEIR RATED % AT FULL RATED CURRENT. So, with an 3% input reactor and a 5% output reactor, that's 8% of the supply voltage gone at full load. Let's see, at 480VAC, that's 28.8V. Better hope your customer has a nice high voltage supply or there is going to be low voltage problems at the motor at full speed and full load.

Reactors are not the solution for every problem and they often make poor insurance too. Tom Jenkins has it right. Most of the time you don't need any, especially if you choose a good (that's an MG1P31) motor.