When instlling VFD's

I'm joining this conversation a little late so I hope no none minds if I throw my 2 cents in.

Keeping your motor lead length as short as possible is always preferred but you can get away with long lengths if you do it right.

1. Turn your carrier frequency down as low as possible. (This reduces the severity of the reflected wave)

2. Use high quality low capacitance, shielded VFD cable. (This further reduces the reflected wave issues and reduces high charging currents on start up.)

3. Spec your motor to have the highest voltage rated insulation you can get. (Even if there is some reflected wave happening the better insulation can withstand it better.)

4. If your VFD has a parameter that helps reduce reflected waves, turn it on. (In AB drives the software drops pulses to help break up refled waves.)

Check out these links, I've found them to be useful and informative.

https://literature.rockwellautomation.com/idc/groups/literature/documents/in/drives-in001_-en-p.pdf

https://literature.rockwellautomation.com/idc/groups/literature/documents/wp/drives-wp019_-en-p.pdf
 
The load reactor looks like a transformer.

Yes it does.

I forgot to mention in my previous post that installing a load reactor or filter can also help, but they don't fix everything. They each have pros and cons, and installation position in relation to the motor and the drive can be critical.
 
Button

PU
EXT

Operation mode switchover
Used to switch between the PU and
External operation mode.
When using the External operation mode
(operation using a separately connected
frequency setting potentiometer and start
signal), press this key to light up the EXT
indication.
(Press MODE simultaneously (0.5s) (Refer to
page 54), or change Pr. 79 setting to change
to combined mode .)
PU: PU operation mode
EXT: External operation mode
Cancels PU stop also.
 
Look into the specific drive you're intending on purchasing on maximum motor lengths.

This is an extreme example, but it just so happens that yesterday, I put an ABB ACS310 on a 230v well pump that is 720' in the ground. I just learned a hard lesson. The drive would throw a ground fault alarm at startup due to "excessive motor cable length" per the manual.

Per ABB tech support, I installed a TCI V1k dv/dt filter with a TCI KDR line reactor at their recommendation to help mitigate the issues. But the motor lead length is still beyond what ABB manual allows.

I was also told, higher end drives as well as oversizing VFD's are possible options, as they often come with a longer allowable motor lead length that is less restricting.

Just a heads up. Do your homework first.
 
Look into the specific drive you're intending on purchasing on maximum motor lengths.

This is an extreme example, but it just so happens that yesterday, I put an ABB ACS310 on a 230v well pump that is 720' in the ground. I just learned a hard lesson. The drive would throw a ground fault alarm at startup due to "excessive motor cable length" per the manual.

Per ABB tech support, I installed a TCI V1k dv/dt filter with a TCI KDR line reactor at their recommendation to help mitigate the issues. But the motor lead length is still beyond what ABB manual allows.

I was also told, higher end drives as well as oversizing VFD's are possible options, as they often come with a longer allowable motor lead length that is less restricting.

Just a heads up. Do your homework first.


I haven't found what the length is yet been going threw the manual and sent a text to the guy I order these from waiting to hear back.
 
All the above recommendations are good. Here's the cable you could use: https://lappusa.lappgroup.com/motors-drives-cable.html

Some vendors don't have all the specs in one manual unfortunately. But, most will have the same basic problem, without a 'software solution', since the IGBT's are mostly the same for all manufacturers.

I generally suggest similar to the statement above, bu thingstodo:
As mentioned, over 200, maybe 250 feet, you add load reactors (5% or 3% of full load current, depending on who you talk to). This stretches out the pulses, rounds out the corners sort of.

Over 250 you can use a dv/dt filter up to around 1000 feet. This further stretches the voltage changes.

Over 1000 feet you are best to use a sine wave filter. Output of the sine wave filter only looks like a sine wave at rated current, frequency, and voltage.

But I would limit the first step (w/o an output reactor) to about 100'. I'd also suggest input reactors on any application. Our power is not getting any cleaner!
 

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