Re: [Emc-users] Input Line Filters?

[Dave Cole]

I would definitely put a reactor, filter/s, or isolation transformer on 
the front end of the cheap drives.
If you are not running the drive cables (the cables between the drives 
and the motors) in conduit or metallic seal tite, I would use shielded 
cable.
Otherwise you risk RFI issues.     I've seen some horrible RFI issues 
with cheap AC drives.


Some drives require reactors between the drives and the motors if the 
line lengths are long..  like over 100 ft.


I've had good luck with Automation Directs line filters.  And you can 
run multiple AC drives off a single Automation Direct filter, but you 
need to make sure you don't exceed the current ratings, etc.


Dave

On 8/15/2019 5:21 PM, Todd Zuercher wrote:

I am preparing to install a half dozen el cheapo Chinese VFDs on a machine.  
Any one have any idea if I need to or should be putting input line filters on 
them?  No mention of anything like this in the Chinglish manual.  If so how do 
you choose what size?  Could I use 1 big one, or will I need a separate one for 
each drive?
How about rectifiers on the output lines?  I'm assuming those are rated by kva.

They are 3ph 220v 3kw drives and spindle motors.

Is it possible to set the speed on all of these using a single analog command 
signal (they will all need to run at the same speed anyway.)

Todd Zuercher
P. Graham Dunn Inc.
630 Henry Street
Dalton, Ohio 44618
Phone:  (330)828-2105ext. 2031


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Re: [Emc-users] Input Line Filters?

[Gregg Eshelman via Emc-users]

A properly made VFD should have nothing between it and the motor, except 
perhaps a manual disconnect, which you'd only open after the input power is 
disconnected. If the VFDs have a remote control input like RS485, USB, a 
network jack etc. it should be possible to use an SBC like a Raspberry Pi or 
Beagle Bone to have a single control input and multiple outputs. If high 
precision  matching of the motor speeds is required a setup like that could be 
programmed to individually adjust the signal to each VFD and motor pair. Get 
things mapped well and when you turn the control to 500 RPM you could be 
confident that all the motors are turning really close to that.
 
If the VFDs have a way to sense if the motor is actually turning at the desired 
speed, and can communicate through their remote port, you could have remote 
sensing of motor failure or jams and have the SBC shut it all down.

On Thursday, August 15, 2019, 5:54:36 PM MDT, Todd Zuercher 
 wrote:  
 I am preparing to install a half dozen el cheapo Chinese VFDs on a machine.  
Any one have any idea if I need to or should be putting input line filters on 
them?  No mention of anything like this in the Chinglish manual.  If so how do 
you choose what size?  Could I use 1 big one, or will I need a separate one for 
each drive?
How about rectifiers on the output lines?  I'm assuming those are rated by kva.

They are 3ph 220v 3kw drives and spindle motors.

Is it possible to set the speed on all of these using a single analog command 
signal (they will all need to run at the same speed anyway.)  
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Re: [Emc-users] Input Line Filters?

[andy pugh]

On Fri, 16 Aug 2019 at 01:53, Todd Zuercher  wrote:

> I am preparing to install a half dozen el cheapo Chinese VFDs on a
> machine.  Any one have any idea if I need to or should be putting input
> line filters on them?  No mention of anything like this in the Chinglish
> manual.  If so how do you choose what size?  Could I use 1 big one, or will
> I need a separate one for each drive?


The filters are given a rating including  the power output they are
intended for
They are very cheap on eBay, but if this is a commercial installation then
eBay might not be a viable source.
"Rasmi" is a good search term, they don't seem to make anything but power
filters.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916

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Re: [Emc-users] Input Line Filters?

[Jon Elson]

On 08/15/2019 04:21 PM, Todd Zuercher wrote:

I am preparing to install a half dozen el cheapo Chinese VFDs on a machine.  
Any one have any idea if I need to or should be putting input line filters on 
them?  No mention of anything like this in the Chinglish manual.  If so how do 
you choose what size?  Could I use 1 big one, or will I need a separate one for 
each drive?
How about rectifiers on the output lines?  I'm assuming those are rated by kva.

RECTIFIERS on the VFD output?  Or, did you mean reactors?  
If 50/60 Hz motors, it should not need reactors.  Some high 
frequency motors may need reactors on the outputs to reduce 
circulating currents due to the very low inductance of those 
motors.

Is it possible to set the speed on all of these using a single analog command 
signal (they will all need to run at the same speed anyway.)

You might run into ground loop issues tying multiple VFDs to 
one speed control voltage.
VFDs are pretty big noise sources.  But, some of the better 
VFDs have a totally floating analog input section, and those 
should be fine.  The really cheap VFDs do not isolate the 
analog input from the mains rectifier, and those would cause 
a fireworks show if you connect the inputs of several 
together.  Better check with an Ohmmeter.


Jon


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[Emc-users] Input Line Filters?

[Todd Zuercher]

I am preparing to install a half dozen el cheapo Chinese VFDs on a machine.  
Any one have any idea if I need to or should be putting input line filters on 
them?  No mention of anything like this in the Chinglish manual.  If so how do 
you choose what size?  Could I use 1 big one, or will I need a separate one for 
each drive?
How about rectifiers on the output lines?  I'm assuming those are rated by kva.

They are 3ph 220v 3kw drives and spindle motors.

Is it possible to set the speed on all of these using a single analog command 
signal (they will all need to run at the same speed anyway.)

Todd Zuercher
P. Graham Dunn Inc.
630 Henry Street
Dalton, Ohio 44618
Phone:  (330)828-2105ext. 2031


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