VFD Motor Load Reactor 5

[itsmoked]

For a 3ph, 5hp, 460V, motor a 1000ft from its VFD what do you suggest for protection from standing wave issues, a reactor?

For a line/load reactor (from MTE) I'm seeing numbers like $800!!!

Do I want a Line/Load reactor, or a sine wave motor protection filter? Or, a DV/DT Motor protection filter?

You can't just use an input reactor on the output can you?




Keith Cress
kcress -

http://www.flaminsystems.com

 

[dpc]

Keith,

You might check with these guys also:

http://www.transcoil.com/Products/VFDOutputSide.nws

I'm pretty sure you don't need a sine wave filter. The DV/DT is the concern for long output leads.

AFAIK, the output reactors are pretty similar to the input reactors.

But I'm sure the experts will be along shortly.....

Dave

 

[CJCPE]

Both Trans-Coil and MTE seem to be recommending dv/dt filters for 1000 ft. The list prices are $527 for the former and $702 for the latter in a NEMA 1 enclosure. The net selling prices are likely competitive with each other, so the net selling price is likely to be somewhat less than $500. Just reactors are only good for short distances and sine wave filters are only needed for longer distances.

 

[itsmoked]

Thanks gents. That is what I'm starting to see in my thrashing about.

It seems a lot of reactor makers are saying that theirs can be applied to the input OR the output, calling them input/output reactors.

Of course I think I'd be fighting the dV/dT fight in this case which they don't seem to mention with the exception of MTE who makes "dV/dT filters". Which mysteriously enough, weight exactly the same 74lbs as the input/output reactors. Me thinks this is whole thing is just an exercise in label swapping..

Keith Cress
kcress -

http://www.flaminsystems.com

 

[DickDV]

In order of increasing protection, line reactor, dv/dt filter, and sine filter. And that applies for both input and output sides of a drive.

For 5hp, 460V, 1000ft, and an MG1 P31 motor, I would expect a sine filter would be required. I have application data from MTE and TCI and, if I'm reading it right, that's the judgement from both.

1000ft motor leads is simply extreme length on a drive and, yes, the sine filter generally will cost about as much as the drive.

 

[burnt2x]

How about moving the drive a bit closer to the driven motor? We did this once but I guess a different case is just different! LOL

 

[jraef]

Keith,
The only difference is a set of filter components (essentially snubber circuit) on a PC board, adds no weight.




"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[itsmoked]

burnt2X; It is a deep well. Very hard to fit that drive down the hole. Even worse trying to poke the little buttons down there.

I'm going to have them re-evaluate a DOL installation. Barring that, they need to go with the Full Monty $$$.

jraef; Thanks for that detail.

I learned something here, Thanks all.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Very hard to fit that drive down the hole. Even worse trying to poke the little buttons down there.

Nah, you just need a bigger hole or longer fingers....

I once did work in developing a submersible VFD for a company in Oregon called Selectric who made one that did fit down the hole with the motor. All they had coming back up the pipe was the power leads and a comm link for the operator interface. One of those great ideas in theory, not terribly practical in reality.

 

[itsmoked]

It actually makes good sense! Just the execution was off.

You need to communicate with the drive using carrier current so you don't need a highly problematic little cable for it, which has to add fragility and cost.

The VFD could be insanely small with the inherent water cooling.

Lets do it.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

What didn't work about it was that the technology to make a truly submersible package was not (is not?) there. One tiny little leak and it was all over, so then you had to look at the cost of pulling a pump/motor/drive combo up from a deep well because the drive crapped out. The first customer that had to do that sent them a bill for the expese and the litigation costs to defend themselves forced them to abandon the idea.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[ozmosis]

If the motor is on a submersible pump, then often the pump manufacturer will demand a dv/dt or sinewave filter as a minimum between VFD and their pump motor. I know Grundfos do.
Do not forget the voltage drop in the reactor/filter. It is an often missed factor and can lead to increased current demand if not factored in.

 

[MAGTiger]

Keep in mind that the voltage drop of a reactor is almost entirely reactive so it doesn't directly subtract from the supplied voltage from the drive. Use vector math. You'll find that it causes a relatively small drop for a 1.5% filter. you probably won't loose more then 0.7%. Also be careful not to over do the cable oversizing. Obviously you need some oversize to compensate for the resistive drop, but that oversized cable has additional capacitance which is the real enemy here.

Neil