Schaublin 125-CNC retrofit.

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19 Dec 2021 18:22 #229501 by Alexander470815
Well I was one of them saying that this does not work.
The line reactor is made to improve the power factor of the drive, it reduces the pulse current pulled from the mains.

Additional stress for the motor windings comes from two factors.
-higher voltage (with long cables much higher than the DC bus voltage >1000V at a 400V VFD )
-super fast voltage rise and fall times (highest with short cables)

Basically you want to remove these high frequency parts from the output waveform.
For a working filter just a inductor wont cut it.
RC, LR filters have super high losses and are only good for signal purposes.
So we are down to a LC Filter as a low pass to only let through the power for the motor and not this PWM rubbish.

These things are called output filters and are available from many manufacturers.
I have seen them from Siemens, SEW, Lenze, Danfoss and others too.
They are all connected between the drive and the motor.

To make yourself a picture I can recommend this document.
files.danfoss.com/download/Drives/doc_MG90N502.pdf

Or in German:
files.danfoss.com/download/Drives/doc_MG90N503.pdf

On Page 13 and 15 you can see the filters compared.
A dU/dT Filter is basically just a weaker version of a sine wave filter.
With this you can truly get a sinusoidal voltage for the motor.

This will help to not fry the windings of the motor.

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19 Dec 2021 22:58 - 20 Dec 2021 03:20 #229523 by spumco
Replied by spumco on topic Schaublin 125-CNC retrofit.
Mark,

I don't have a youtube account so I can't reply to comments there.

Line/load reactors are the same thing*, and contrary to some of the YT comments they aren't transformers.  They also aren't the same thing as input or output side EMI/RFI filters.

Rather than taking my word for it, please feel free to peruse a number of 'professional' discussions of load reactors - including Lenze.

-Ralph

trimantec.com/blogs/t/why-use-line-reactor

ctmmagnetics.com/what-are-lineload-reactors/

www.galco.com/circuit/reacsolu.htm


* - same device, but called 'line' when installed between VFD and incoming line voltage and 'load' or 'output' between VFD and motor

 
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Last edit: 20 Dec 2021 03:20 by spumco. Reason: Additional infor & sources

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20 Dec 2021 05:43 #229541 by Alexander470815
Line and load reactor are quite similar.

But a load reactor will do very little to keep away those voltage spikes and high voltage rise times from the motor insulation.

When using a Motor with unknown insulation status it is best to use at least a dv/dt (dU/dt) Filter or even better a sine wave filter.
The last of them will give the motor a truly sinusoidal voltage.

dv/dt and sine wave filters are more than just a reactor.
They are LC filters, they are even mentioned in your first link.

I suggest you read the output filter design guide from danfoss that I posted a link to.
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02 Jan 2022 11:03 #230536 by RotarySMP
I didn't get much done over the holidays...
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09 Jan 2022 12:55 #231245 by RotarySMP
After teasing it a few times, this week I really did make electrical installation progress.
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10 Jan 2022 09:37 #231293 by arvidb
Replied by arvidb on topic Schaublin 125-CNC retrofit.
For drawing wiring diagrams, QElectroTech works very nicely! It lets you e.g. place contactor coils and contacts in different places/pages and then keeps track of where they are for you.

Example diagram:
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10 Jan 2022 15:35 - 15 Jan 2022 20:24 #231312 by RotarySMP
Thanks. That has got to be better than doing it in Visio (Mini-lathe) or PDF writer (Changing the Maho schematics one line at a time.

I'll give that a try.
Mark
Last edit: 15 Jan 2022 20:24 by RotarySMP.

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14 Jan 2022 04:41 #231729 by spumco
Replied by spumco on topic Schaublin 125-CNC retrofit.
I'll have to check out QElectro Tech.  Looks nice.

TinyCAD is another useful tool.  Not great for ladder diagrams, but excellent for color-coded schematics.  Bit of a steep learning curve designing your own symbols but once you figure it out it's easy to cook up specialized components like PLC's, drives and sensors.

sourceforge.net/projects/tinycad/

 

 
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15 Jan 2022 12:05 #231887 by RotarySMP
Nice schematic.
I think QET is really good. Probably capable of 10x what I need, but that way you can place and snap components on the grid and auto connect then is really fast to use.
Mark

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16 Jan 2022 11:01 #232001 by RotarySMP
Thanks to Arvidb for the idea of this week video...


...pretty random, but I hope regular viewers can follow it.
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