Anyone live in North Florida or South Georgia?
Hello Guys,
?
Does anyone live in North Florida or South Georgia in the group?
?
The past 15 years we have been in the South and away from friends and family where I grew up and worked in Western NY. Haven’t found anyone with similar interests close by.?
We live 20 minutes South of Thomasville, GA in North Florida.
?
Been tired of talking to myself and our dogs for awhile now. Anyone close?
?
Regards,
Mike
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Re: vfd load reactor suggestions?
Hi Ross
All noted , and thanks for the sine filter link
My “how it works” comments were directed more to Sierra
The theme of this discussion has been whether EMCO motors can be damaged by use with a VFD , and if so how to mitigate it
The Sine Filter option crept into the thread after Carl reported that after damaging two motors with his inverter , he had installed a sine filter and no further problems? . .? I agree that simpler things like a small inductor would help and that is how we got onto microwave oven transformers ?
Regards,
Carvel ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Morepork via groups.io
Sent: Monday, March 24, 2025 2:19 AM
To: [email protected]
Subject: Re: [emcoV10lathe] vfd load reactor suggestions? ? Thanks Carvel, but my question was to Sierra as to the problem he wants to resolve by using a load filter, not what this does.? I'm well versed in principles of filters (reactor/chokes, sine filters, dv/dt filter etc.) being formally trained in power electronics - though this was many years ago:) Why I asked Sierra this question is to try to understand if the filter will be used to allow the output from the VDF to be motor friendly, resolve issues with harmonics, or problems with cable resonance from long cable lenghts. This would help in deciding on what filter is require. Harmonics will require a sine filter but if you just need to knock of the voltage spikes and so they are not reflected back, thus protecting the motor and VFD, then cheap dv/dt (EMC) filter should work - maybe even just a small inductor could work. Try also to keep the load cable as short as possible.? There are are sine filters on Aliexpress if you want to go down that route.? Haven't used them so cant comment on their quality but they seem to be affordable. ?
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Re: vfd load reactor suggestions?
Hi Vedran
Don’t know what the B-H curve for Microwave Oven Transformer looks like . It would make sense to operate near saturation as that would give a constant voltage feed for the magnetron
Maybe one of our members with a spare transformer , a variable supply and a couple of multimeters could measure it for us
Don’t think it would impact this application as the value is not critical
Regards,
Carvel ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Vedran via groups.io
Sent: Sunday, March 23, 2025 10:47 PM
To: [email protected]
Subject: Re: [emcoV10lathe] vfd load reactor suggestions? ? I'd chisel or hacksaw-off the secondary... 2000V is not something one just shakes off and hobbyists sometimes tend to keep kludges outside of appropriate enclosures. No need to press out what is left of copper inside the core after you cut the exposed parts off. Broken microwaves are regularly found at e-waste and metal scrapping places. Transformers are usually undamaged.? When taking one apart there are a few things to know 1. They contain a HV capacitor... usually it has a high value resistor in series so it drains in minutes to hours after being unplugged, but always assume the thing is alive and deadly. These also go up to 2000V. You can use a high value resistor across its terminals to drain the charge but you need to connect it with a known-good insulated pliers or similar tool. If you think the thing is discharged, confirm by sticking something metal across its contacts... needle nose pliers work pretty good. This tool also needs to be well insulated. And if it turns out the thing still has charge, you'll get a loud crack, big spark and a black mark on your tool to remind you of the event. 2. Magnetron contains two big and somewhat powerful ring magnets. These can be extracted, but they are secured with white or pink ceramic heat resistant material. Supposedly white is aluminium based and not particularly dangerous, but pink one is beryllium based and is a big health hazard if you inhale it (in dust form). I'm not sure how much of a risk this is, like if you'd have to sand the thing and sniff the dust or would just breaking the thing apart and being in the same room be enough. I also have no idea if color is actually tightly correlated to the material type, ie. if the white ones are always safe. In any case, do your own diligence if you plan to mess with one. As I understand, MOT cores are made to run on the edge of saturation - they even have magnetic shunts to dump a bit of flux. Does this matters in our case? You want magnetic coupling in transformers and in common/differential mode chokes, but not in this case. ? ? The goal is to have the magnetic fields linked.
Hi Bill
An interesting idea ?
You would just need to find 3 transformers with intact primaries with the same inductance
Coincidentally this might even be in the correct ball park ?
I have a figure in my head for the VFD inductor of ?10-30 μH/kW? . . . maybe someone else can confirm? . . . and a quick search throws up values of 20-30 μH for medium size microwaves ? !
Just need to have someone with a multimeter that can measure inductance and start scrounging !
If you do go this route and leave the secondary winding ( unused for this ) in place just make sure the output terminals are well screened as you could have very high voltages appearing across them when there is current flowing through the Primary !
Regards,
Carvel ? From: [email protected] [mailto:[email protected]] On Behalf Of Bill Nite via
Sent: Sunday, March 23, 2025 7:05 PM
To: [email protected]
Subject: Re: [emcoV10lathe] vfd load reactor suggestions? ? If you’re looking for cheap, I have a DIY choke idea for you. The concept design came from a project I was researching to convert a straight AC welder to DC output, so the purpose of the choke was to help smooth the output of a bridge rectifier. I don’t know how if its capabilities falls within the range of what’s needed to protect your motor from the high voltage in your situation, but maybe Carvel or others can chime in to add their expertise to either say it won’t work, or possibly suggest tweaks to make it work. The design centers around the transformer from a scrap microwave oven. You cut the weld on each side of the transformer that holds the two halves of the laminations together. This allows you to remove the two coils and replace them with a single coil that can handle the current it needs to pass. In the case of the welder this choke is in series with the stinger of the welder, so it has to carry in the range of 100 to 200 amps, big wire, so you can only get about 9 wraps of wire, but this was supposedly sufficient. In your case you can use much smaller wire which allows more wraps and as a result better smoothing of the signal. Just thinking off top of my head here, but the primary coil originally in the transformer might have enough ampacity for your application. Maybe you won’t even have to cut it apart and install a new coil, just wire through the primary side of the transformer. I’m sure that the number of coils affects the inductance, and that in turn likely affects the frequency that it filters out, but how to figure that out I have no clue.?
Ok people who know the electrical theory please comment. It’ll be cheap but it might not work. Oh and I guess you’re going to need three of these, one for each leg coming off the VFD? Remember though, they're cheap. They’re on the side of the road all the time. I happen to come across something saying that treadmills have chokes on their motors, so that’s another possible source that you can scrap from things people throw away. Search microwave oven transformer on YouTube and you can find all sorts of fun things they’re good for.? Bill Nite (knows enough electrical to be dangerous)
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Re: vfd load reactor suggestions?
I have an original (old) emco 240v 3ph motor which I am running via a vfd and I don't want to wipe out the motor's insulation from the vfd spikes. It is an intermittent us hobby machine, from project to project. Sierra
On Sunday, March 23, 2025 at 05:18:41 PM PDT, Morepork via groups.io <ross.a.jennings@...> wrote:
Thanks Carvel, but my question was to Sierra as to the problem he wants to resolve by using a load filter, not what this does.? I'm well versed in principles of filters (reactor/chokes, sine filters, dv/dt filter etc.) being formally trained in power electronics - though this was many years ago:)
?
Why I asked Sierra this question is to try to understand if the filter will be used to allow the output from the VDF to be motor friendly, resolve issues with harmonics, or problems with cable resonance from long cable lenghts. This would help in deciding on what filter is require.
?
Harmonics will require a sine filter but if you just need to knock of the voltage spikes and so they are not reflected back, thus protecting the motor and VFD, then cheap dv/dt (EMC) filter should work - maybe even just a small inductor could work. Try also to keep the load cable as short as possible.?
?
There are are sine filters on Aliexpress if you want to go down that route.? Haven't used them so cant comment on their quality but they seem to be affordable. ?
?
Ross
|
Re: vfd load reactor suggestions?
Thanks Carvel, but my question was to Sierra as to the problem he wants to resolve by using a load filter, not what this does.? I'm well versed in principles of filters (reactor/chokes, sine filters, dv/dt filter etc.) being formally trained in power electronics - though this was many years ago:)
?
Why I asked Sierra this question is to try to understand if the filter will be used to allow the output from the VDF to be motor friendly, resolve issues with harmonics, or problems with cable resonance from long cable lenghts. This would help in deciding on what filter is require.
?
Harmonics will require a sine filter but if you just need to knock of the voltage spikes and so they are not reflected back, thus protecting the motor and VFD, then cheap dv/dt (EMC) filter should work - maybe even just a small inductor could work. Try also to keep the load cable as short as possible.?
?
There are are sine filters on Aliexpress if you want to go down that route.? Haven't used them so cant comment on their quality but they seem to be affordable. ?
?
Ross
|
Re: vfd load reactor suggestions?
I'd chisel or hacksaw-off the secondary... 2000V is not something one just shakes off and hobbyists sometimes tend to keep kludges outside of appropriate enclosures. No need to press out what is left of copper inside the core after you cut the exposed parts off. Broken microwaves are regularly found at e-waste and metal scrapping places. Transformers are usually undamaged.?
When taking one apart there are a few things to know 1. They contain a HV capacitor... usually it has a high value resistor in series so it drains in minutes to hours after being unplugged, but always assume the thing is alive and deadly. These also go up to 2000V. You can use a high value resistor across its terminals to drain the charge but you need to connect it with a known-good insulated pliers or similar tool. If you think the thing is discharged, confirm by sticking something metal across its contacts... needle nose pliers work pretty good. This tool also needs to be well insulated. And if it turns out the thing still has charge, you'll get a loud crack, big spark and a black mark on your tool to remind you of the event. 2. Magnetron contains two big and somewhat powerful ring magnets. These can be extracted, but they are secured with white or pink ceramic heat resistant material. Supposedly white is aluminium based and not particularly dangerous, but pink one is beryllium based and is a big health hazard if you inhale it (in dust form). I'm not sure how much of a risk this is, like if you'd have to sand the thing and sniff the dust or would just breaking the thing apart and being in the same room be enough. I also have no idea if color is actually tightly correlated to the material type, ie. if the white ones are always safe. In any case, do your own diligence if you plan to mess with one.
Carvel As I understand, MOT cores are made to run on the edge of saturation - they even have magnetic shunts to dump a bit of flux. Does this matters in our case?
Chris You want magnetic coupling in transformers and in common/differential mode chokes, but not in this case.
The goal is to have the magnetic fields linked.
Chris P
Hi Bill
An interesting idea ?
You would just need to find 3 transformers with intact primaries with the same inductance
Coincidentally this might even be in the correct ball park ?
I have a figure in my head for the VFD inductor of ?10-30
μH/kW?
. . . maybe someone else can confirm? . . . and a quick search throws up values of 20-30
μH
for medium size microwaves ? !
Just need to have someone with a multimeter that can measure inductance and start scrounging !
If you do go this route and leave the secondary winding ( unused for this ) in place just make sure the output terminals are well screened as you could have very high voltages appearing across them when there is current flowing through the Primary !
Regards,
Carvel
?
From: [email protected] [mailto:[email protected]]
On Behalf Of Bill Nite via
Sent: Sunday, March 23, 2025 7:05 PM
To: [email protected]
Subject: Re: [emcoV10lathe] vfd load reactor suggestions?
?
If you’re looking for cheap, I have a DIY choke idea for you. The concept design came from a project I was researching to convert a straight AC welder to DC output, so the purpose of the choke was to help
smooth the output of a bridge rectifier. I don’t know how if its capabilities falls within the range of what’s needed to protect your motor from the high voltage in your situation, but maybe Carvel or others can chime in to add their expertise to either say
it won’t work, or possibly suggest tweaks to make it work. The design centers around the transformer from a scrap microwave oven. You cut the weld on each side of the transformer that holds the two halves of the laminations together. This allows you to remove
the two coils and replace them with a single coil that can handle the current it needs to pass. In the case of the welder this choke is in series with the stinger of the welder, so it has to carry in the range of 100 to 200 amps, big wire, so you can only
get about 9 wraps of wire, but this was supposedly sufficient. In your case you can use much smaller wire which allows more wraps and as a result better smoothing of the signal. Just thinking off top of my head here, but the primary coil originally in the
transformer might have enough ampacity for your application. Maybe you won’t even have to cut it apart and install a new coil, just wire through the primary side of the transformer. I’m sure that the number of coils affects the inductance, and that in turn
likely affects the frequency that it filters out, but how to figure that out I have no clue.?
Ok people who know the electrical theory please comment. It’ll be cheap but it might not work. Oh and I guess you’re going to need three of these, one for each leg coming off the VFD? Remember though, they're cheap. They’re on the side of the road all the time.
I happen to come across something saying that treadmills have chokes on their motors, so that’s another possible source that you can scrap from things people throw away. Search microwave oven transformer on YouTube and you can find all sorts of fun things
they’re good for.?
Bill Nite (knows enough electrical to be dangerous)
|
Re: vfd load reactor suggestions?
The goal is to have the magnetic fields linked.
Chris P
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Show quoted text
Hi Bill
An interesting idea ?
You would just need to find 3 transformers with intact primaries with the same inductance
Coincidentally this might even be in the correct ball park ?
I have a figure in my head for the VFD inductor of ?10-30
μH/kW?
. . . maybe someone else can confirm? . . . and a quick search throws up values of 20-30
μH
for medium size microwaves ? !
Just need to have someone with a multimeter that can measure inductance and start scrounging !
If you do go this route and leave the secondary winding ( unused for this ) in place just make sure the output terminals are well screened as you could have very high voltages appearing across them when there is current flowing through the Primary !
Regards,
Carvel
?
From: [email protected] [mailto:[email protected]]
On Behalf Of Bill Nite via groups.io
Sent: Sunday, March 23, 2025 7:05 PM
To: [email protected]
Subject: Re: [emcoV10lathe] vfd load reactor suggestions?
?
If you’re looking for cheap, I have a DIY choke idea for you. The concept design came from a project I was researching to convert a straight AC welder to DC output, so the purpose of the choke was to help
smooth the output of a bridge rectifier. I don’t know how if its capabilities falls within the range of what’s needed to protect your motor from the high voltage in your situation, but maybe Carvel or others can chime in to add their expertise to either say
it won’t work, or possibly suggest tweaks to make it work. The design centers around the transformer from a scrap microwave oven. You cut the weld on each side of the transformer that holds the two halves of the laminations together. This allows you to remove
the two coils and replace them with a single coil that can handle the current it needs to pass. In the case of the welder this choke is in series with the stinger of the welder, so it has to carry in the range of 100 to 200 amps, big wire, so you can only
get about 9 wraps of wire, but this was supposedly sufficient. In your case you can use much smaller wire which allows more wraps and as a result better smoothing of the signal. Just thinking off top of my head here, but the primary coil originally in the
transformer might have enough ampacity for your application. Maybe you won’t even have to cut it apart and install a new coil, just wire through the primary side of the transformer. I’m sure that the number of coils affects the inductance, and that in turn
likely affects the frequency that it filters out, but how to figure that out I have no clue.?
Ok people who know the electrical theory please comment. It’ll be cheap but it might not work. Oh and I guess you’re going to need three of these, one for each leg coming off the VFD? Remember though, they're cheap. They’re on the side of the road all the time.
I happen to come across something saying that treadmills have chokes on their motors, so that’s another possible source that you can scrap from things people throw away. Search microwave oven transformer on YouTube and you can find all sorts of fun things
they’re good for.?
Bill Nite (knows enough electrical to be dangerous)
|
Re: vfd load reactor suggestions?
Hi Bill
An interesting idea ?
You would just need to find 3 transformers with intact primaries with the same inductance
Coincidentally this might even be in the correct ball park ?
I have a figure in my head for the VFD inductor of ?10-30 μH/kW? . . . maybe someone else can confirm? . . . and a quick search throws up values of 20-30 μH for medium size microwaves ? !
Just need to have someone with a multimeter that can measure inductance and start scrounging !
If you do go this route and leave the secondary winding ( unused for this ) in place just make sure the output terminals are well screened as you could have very high voltages appearing across them when there is current flowing through the Primary !
Regards,
Carvel ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Bill Nite via groups.io
Sent: Sunday, March 23, 2025 7:05 PM
To: [email protected]
Subject: Re: [emcoV10lathe] vfd load reactor suggestions? ? If you’re looking for cheap, I have a DIY choke idea for you. The concept design came from a project I was researching to convert a straight AC welder to DC output, so the purpose of the choke was to help smooth the output of a bridge rectifier. I don’t know how if its capabilities falls within the range of what’s needed to protect your motor from the high voltage in your situation, but maybe Carvel or others can chime in to add their expertise to either say it won’t work, or possibly suggest tweaks to make it work. The design centers around the transformer from a scrap microwave oven. You cut the weld on each side of the transformer that holds the two halves of the laminations together. This allows you to remove the two coils and replace them with a single coil that can handle the current it needs to pass. In the case of the welder this choke is in series with the stinger of the welder, so it has to carry in the range of 100 to 200 amps, big wire, so you can only get about 9 wraps of wire, but this was supposedly sufficient. In your case you can use much smaller wire which allows more wraps and as a result better smoothing of the signal. Just thinking off top of my head here, but the primary coil originally in the transformer might have enough ampacity for your application. Maybe you won’t even have to cut it apart and install a new coil, just wire through the primary side of the transformer. I’m sure that the number of coils affects the inductance, and that in turn likely affects the frequency that it filters out, but how to figure that out I have no clue.?
Ok people who know the electrical theory please comment. It’ll be cheap but it might not work. Oh and I guess you’re going to need three of these, one for each leg coming off the VFD? Remember though, they're cheap. They’re on the side of the road all the time. I happen to come across something saying that treadmills have chokes on their motors, so that’s another possible source that you can scrap from things people throw away. Search microwave oven transformer on YouTube and you can find all sorts of fun things they’re good for.? Bill Nite (knows enough electrical to be dangerous)
|
Re: vfd load reactor suggestions?
Sierra,
?
If you’re looking for cheap, I have a DIY choke idea for you. The concept design came from a project I was researching to convert a straight AC welder to DC output, so the purpose of the choke was to help smooth the output of a bridge rectifier. I don’t know how if its capabilities falls within the range of what’s needed to protect your motor from the high voltage in your situation, but maybe Carvel or others can chime in to add their expertise to either say it won’t work, or possibly suggest tweaks to make it work. The design centers around the transformer from a scrap microwave oven. You cut the weld on each side of the transformer that holds the two halves of the laminations together. This allows you to remove the two coils and replace them with a single coil that can handle the current it needs to pass. In the case of the welder this choke is in series with the stinger of the welder, so it has to carry in the range of 100 to 200 amps, big wire, so you can only get about 9 wraps of wire, but this was supposedly sufficient. In your case you can use much smaller wire which allows more wraps and as a result better smoothing of the signal. Just thinking off top of my head here, but the primary coil originally in the transformer might have enough ampacity for your application. Maybe you won’t even have to cut it apart and install a new coil, just wire through the primary side of the transformer. I’m sure that the number of coils affects the inductance, and that in turn likely affects the frequency that it filters out, but how to figure that out I have no clue.?
Ok people who know the electrical theory please comment. It’ll be cheap but it might not work. Oh and I guess you’re going to need three of these, one for each leg coming off the VFD? Remember though, they're cheap. They’re on the side of the road all the time. I happen to come across something saying that treadmills have chokes on their motors, so that’s another possible source that you can scrap from things people throw away. Search microwave oven transformer on YouTube and you can find all sorts of fun things they’re good for.?
Bill Nite (knows enough electrical to be dangerous)
|
Re: V10P Headstock Fiber Gear Replacement
Ryan,
profile shift selects a different section of the same cycloid curve that defines the tooth shape.
So the module, pressure angle and tooth count remain while the center distance changes, and teeth get stronger.
Unit is module.
Bo?o
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Show quoted text
On 22. 3. 25 17:06, Ryan Harmon via groups.io wrote: Further update - I found a different gear generator add in for fusion 360. This one includes a "Profile shifting coef".
This may be exactly what I need. It seems like a profile shift of 0.4 (whatever the unit is) puts me almost exactly at the dimensions I'm measuring from the original.
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Re: vfd load reactor suggestions?
Hi Sierra and Ross
Right? . .? today is Sunday so let’s see what we can do ?
Firstly to recap for Ross as to why we want to do this
The output of a VFD is a square wave of full voltage but varying interval
This output therefore consists not only of the 0 – 60Hz fundamental that the motor wants , but also a lot of high frequency high voltage components which can damage the insulation on older motors and cause motor failure
( In this discussion Carl reported two motor burnouts for this reason before he installed a filter ?)
One option when using a VFD with older motors ?is therefore to use a reactor to reduce these high frequency spikes
Newer motors with higher grade insulation are generally OK
Not all VFD’s are the same and differ in terms of the type of control circuitry and the type of output devices used ( MOSFET or IGBT’s ) so some VFDs are happy to look into a load reactor while others such as your TECO example might not be
Both my Yaskawa and Hitachi drives show load reactors as standard options? . .? see this example ?. . ..but check the owner’s manual for yours first ?
So to come back to Sierra’s question? , what is a reactor and what does it do ?
In this context a reactor is basically a choke which in turn is basically just a coil of wire wound on a laminated steel core
As such it has a certain inductance ( measured in millihenry’s – mH ) and exhibits a certain amount of “AC resistance” to AC current passing through it
HOWEVER? . .? this “AC Resistance” ?which we refer to as “Reactance” is proportional to frequency which is where the trick comes in
So low frequency current at motor frequency goes through virtually unhindered while the high frequency components encounter significant resistance and are therefore filtered out or at least reduced ?
So the gauge of the wire used must be heavy enough to carry the motor current and the insulation must be tough enough to withstand the spikes which it is being subjected to
For completeness , in the VFD literature we will also see reference to “ lineside reactors” ?
These are connected between the mains supply and the VFD on occasion ?
They can be used where the supply is noisy to keep such noise out of the VFD , or to stop noise generated by the VFD from feeding back into the supply and upsetting other sensitive equipment on the same circuit , but these do not normally feature in our applications
Hope this all makes some sense
Carvel
?
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From: [email protected] [mailto:[email protected]] On Behalf Of Sierra Tunafish Monkeymind
Sent: Sunday, March 23, 2025 2:38 AM
To: [email protected]
Subject: Re: [emcoV10lathe] vfd load reactor suggestions?? Ha, this now has me as more confustercatededed than I was before…. except on tuesdays unless it’s Friday, with an added, better better not and soon? So much to consider and it’s hard to know Sierra
On Mar 22, 2025, at 4:09?PM, Morepork via groups.io <ross.a.jennings@...> wrote: ? Sorry cant help with a inxpensive recommendation but you may want to check you VFD manual.? My TECO manual actually recommends NOT adding any capacitive, LC or RC components on the load side.? It does, obviously, recommend a reactor filter for the Line side for improving power quality - PFC and harmonics etc - and line thermal relays. That said, I do understand the reasoning for some DV/Dt sine filtering on the load side for longer cable lenghts to prevent voltage spikes and, I guess more importantly for you, help prevent "laminar squeal" and deteriation of the winding insulation on older motors.? If the latter is the case then the best option, really, is to replace the motor with a inverter duty type, but that could come at a higher cost than a sine filter.
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Re: Ps, Re: [emcoV10lathe] vfd load reactor suggestions?
Please note this explanation works on concept level, and is not always what is actually happening.
VFD itself doesn't produce voltage spikes, it turns the power fully on and fully off very quickly and varies how long it's on each cycle (square wave in the picture below). Effective voltage is an integral of that (sine wave in the picture below). Think about it like blipping a motor on a big wheel bandsaw a few times to get it up to speed slowly. It has a lot of inertia and each time you blip the motor on you add energy to the system.
VFD on-off output is then smoothed by the winding which resists current change, effectively making a low pass current filter - higher frequency is blocked and lower one is allowed through. 
When you switch the power off on the winding (or any inductor) it still opposes any current change and it starts dumping stored magnetic energy to keep the current going, but if you just disconnected the power the current has nowhere to go. This results in a voltage rise (spike) over the winding and this voltage can be significantly larger then what was originally supplied by the VFD. This is similar to the water hammer that occurs when you close off the tap quickly. Spikes are very short and they don't have a whole lot of energy, but you get one each time the VFD switches, which is usually 4-20 thousand times a second (4-20Hz). Maximum voltage the spike will hit depends on the speed the VFD transistor switches off. You could make the transistor turn off slower, but that results in heat (in the transistor) and overall inefficiency which is not good. 
VFDs (good ones at least) include some sort of a freewheeling diode variant that
allows the inductor current to keep flowing after the power is switched
off.
Simplest way is to include a diode in parallel to the inductor so when power is switched off, current can flow the diode instead of through the VFD and "freewheel" between the winding and the diode (VFDs don't actually use diodes for this, but the principle is the same). Bicycle analogy works for this, bad idea circuit is like a fixie - if you try to stop pedalling, the energy in the system will still force your legs up and down. A regular freewheeling bike will allow for the pedals to remain stationary even when the bike is still moving. So far so good, but each wire is an inductor, capacitor and resistor in one, so there are higher order effects because of that and other reasons. For instance, diode needs a bit od time to start conducting. It means it won't get the first (and the worst) of the voltage spike.
When you add filters to the motor, you're either slowing down the switching speed, thus making the spikes smaller or trying to arrest the voltage spikes once they occur (or both).?
On Sun, Mar 23, 2025 at 12:13?AM Sierra Tunafish Monkeymind via <barkingcarpet= [email protected]> wrote:
Ok, so it is there to smoothe it out, but, what of the voltage spikes/wave form whatevers(I’m outta my apples n oranges here) but, don’t the vfd’s output voltage spikes? Are the chokes set or can so set so that it does not go above 240 volts? Yes, I’m confused by it ? Hi Sierra
The choke / reactor is there in series to smooth out the current going through it , so the voltage rating is just an insulation issue
So the voltage rating must be equal to or higher than whatever voltage your VFD is pushing through it
Am I making any sense ?
Carvel ? ? Thank Ye Carvel. I get confused with the voltage ratings on the ones I see listed at 4 and 600v and am unsure if I need something specific for 240v, or if they are rated for higher but limit it via some other parameters or settings? ? Hi Sierra
The chokes / reactors will be heavy , even smaller one ? , so you want something not too far away? . .?
Suggest do a search along the lines of “ VFD load reactor I kW “ and see
I notice lots of stuff , new and used, on our well known auction site ?
Regards,
Carvel ? ? Can anyone point me towards an "inexpensive" load reactor/filter which I can put between my vfd and the older emco motor? The motor is a 3ph 220v .81KW.
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Re: can I drill the hole in the carriage for the cross slide lead screw hole through?
Eric
You'll obviously make your one choice in the end, but if it was my machine, I'd keep the current leadscrew arrangement if possible. I think I went looking once and decided a ball nut should fit inside the space of the original nut without serious modifications to the original casting. I couldn't tell you which size ballscrew I was looking at though. You could probably get away with NEMA 23 size stepper or servo that can be installed with output towards the operator as Roman already showed. If your machine is mounted high enough, you might even be able to mount the motor underneath the carriage where it won't bother you at all. At that point, you can keep the handwheel in the original position on the end of the leadscrew and have the whole thing add just the thickness of the toothed belt pulley in front of the machine.
Keep in mind that classic machine (sliding ways, non ball screw) CNC conversions are not recommended as they tend to wear quickly. When cranking the machine by hand you are rather limited by how fast and how often you can make it move. CNC has almost no such limitations (in practical terms) and will add figurative miles quickly. You should also consider modifying the machine for automatic lubrication to help with wear.
Hi Eric
Thanks for the positive feedback? . . .? the group is what the members make it , so at best we are just really there to grease the wheels? . . .? or should that be lead screws . . . ?
I am not a CNC expert and none of my machines have gone that route , so I will just have to salute as you guys go past
My only suggestion would be that if I was going to engage in some major structural modification to the machine I would try and source a duplicate spare part before I start , so that if it doesn’t work out I can always backtrack to a working original machine ?
Regards,
Carvel ? From: [email protected] [mailto:[email protected]] On Behalf Of eric warner via
Sent: Saturday, March 22, 2025 3:39 PM
To: [email protected]
Subject: Re: [emcoV10lathe] can I drill the hole in the carriage for the cross slide lead screw hole through? ? Thanks for getting back to me.? I figured that one or the other of you would reply :).? I've been on this group for years and greatly appreciate all of your wisdom and help that you have shared with others and I have quietly gleaned over the years.??
A number of years ago I designed and built a CNC retrofit on my V-10 using stepper motors and a MAXNC controller (long gone CNC company running on MS-DOS...).? I ran this system for years and it was one of the best things I did on my lathe.? The controller has subsequently died and I have about a 6" long extension out the front of my lathe now that just always seems to get in the way.? I have a handwheel on the backside of the stepper to manually drive the motor until I get my new CNC controller wired up and running.? I also have a large amount of backlash in the cross slide lead screw, so this got me thinking...??
My thought was to replace the lead screw with a new lead screw and nut (eliminate much of the backlash) and mount the motor on the backside.? I could then run the lead screw out the front and put the nut on the cross slide rather than in the carriage.? The only downside is that the end of the screw will be sticking out the front at the same distance always (unless I add a spline connection and have the lead screw move back and forth through the spline, but I don't think I want to go to that level of complexity...). Originally what got me thinking down this path was that I wanted to put a longer lead screw on so that I could run the cross slide out further to be able to get enough clearance under an 8" diameter part that I need to turn...? That idea is no longer running, but moving the motor to the backside is still on my mind...
Again your help and comments are greatly appreciated!
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Re: FB2 Mill 3 Phase Motor Help
Hi Jay
That ties up with the info which I have from RIFA capacitors and other
The automatic feed with its gearing and inertia can present a significant load even without actually driving a cut , and particularly when cold , so you might have to wire in an additional start capacitor for it? . . .? try it and see but get an extra one when ordering to avoid the irritation ?
Let us know how it goes
Carvel ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jay via groups.io
Sent: Sunday, March 23, 2025 10:33 AM
To: [email protected]
Subject: Re: [emcoV10lathe] FB2 Mill 3 Phase Motor Help ? I was always planning on running the motor at constant speed, and I had forgotten about the capacitor option. I think I might try that in the first instance, and see if I'm happy with that setup. Thanks for the reminder of that.? I found this video giving a guideline on capacitor size: I'm going to get a 3.5uF cap for the power feed, and 20uF for the spindle. I read that a starter cap is only really needed when the motor starts under load, which this will not, so I'll forego that for now.?
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Re: FB2 Mill 3 Phase Motor Help
Hi Carvel,
?
I was always planning on running the motor at constant speed, and I had forgotten about the capacitor option. I think I might try that in the first instance, and see if I'm happy with that setup. Thanks for the reminder of that.?
?
I found this video giving a guideline on capacitor size:
I'm going to get a 3.5uF cap for the power feed, and 20uF for the spindle. I read that a starter cap is only really needed when the motor starts under load, which this will not, so I'll forego that for now.?
?
Thanks
Jay
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Re: vfd load reactor suggestions?
I don’t want to fry the old/original Emco 220v 3ph motor running it on my vfd. It is an intermittent use mostly hobby machine, which goes from project to project as needed and sits between.
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On Mar 22, 2025, at 6:55?PM, Morepork via groups.io <ross.a.jennings@...> wrote:
? Sorry.? Maybe I should have started by asking what is the problem are you trying to resolve with a load reactor/filter???
?
Ross
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Re: vfd load reactor suggestions?
Sorry.? Maybe I should have started by asking what is the problem are you trying to resolve with a load reactor/filter???
?
Ross
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Re: vfd load reactor suggestions?
Ha, this now has me as more confustercatededed than I was before…. except on tuesdays unless it’s Friday, with an added, better better not and soon? So much to consider and it’s hard to know
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On Mar 22, 2025, at 4:09?PM, Morepork via groups.io <ross.a.jennings@...> wrote:
? Hi Sierra,
?
Sorry cant help with a inxpensive recommendation but you may want to check you VFD manual.? My TECO manual actually recommends NOT adding any capacitive, LC or RC components on the load side.? It does, obviously, recommend a reactor filter for the Line side for improving power quality - PFC and harmonics etc - and line thermal relays.
?
That said, I do understand the reasoning for some DV/Dt sine filtering on the load side for longer cable lenghts to prevent voltage spikes and, I guess more importantly for you, help prevent "laminar squeal" and deteriation of the winding insulation on older motors.? If the latter is the case then the best option, really, is to replace the motor with a inverter duty type, but that could come at a higher cost than a sine filter.
?
Anyway good luck.
?
Ross
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Ps, Re: [emcoV10lathe] vfd load reactor suggestions?
Ok, so it is there to smoothe it out, but, what of the voltage spikes/wave form whatevers(I’m outta my apples n oranges here) but, don’t the vfd’s output voltage spikes? Are the chokes set or can so set so that it does not go above 240 volts?
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On Mar 22, 2025, at 3:00?PM, cwlathes via groups.io <carvelw@...> wrote:
? Hi Sierra
The choke / reactor is there in series to smooth out the current going through it , so the voltage rating is just an insulation issue
So the voltage rating must be equal to or higher than whatever voltage your VFD is pushing through it
Am I making any sense ?
Carvel ? ? Thank Ye Carvel. I get confused with the voltage ratings on the ones I see listed at 4 and 600v and am unsure if I need something specific for 240v, or if they are rated for higher but limit it via some other parameters or settings?
On Mar 22, 2025, at 1:11?PM, cwlathes via groups.io <carvelw@...> wrote: ? Hi Sierra
The chokes / reactors will be heavy , even smaller one ? , so you want something not too far away? . .?
Suggest do a search along the lines of “ VFD load reactor I kW “ and see
I notice lots of stuff , new and used, on our well known auction site ?
Regards,
Carvel ? ? Can anyone point me towards an "inexpensive" load reactor/filter which I can put between my vfd and the older emco motor? The motor is a 3ph 220v .81KW.
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Re: vfd load reactor suggestions?
Hi Sierra,
?
Sorry cant help with a inxpensive recommendation but you may want to check you VFD manual.? My TECO manual actually recommends NOT adding any capacitive, LC or RC components on the load side.? It does, obviously, recommend a reactor filter for the Line side for improving power quality - PFC and harmonics etc - and line thermal relays.
?
That said, I do understand the reasoning for some DV/Dt sine filtering on the load side for longer cable lenghts to prevent voltage spikes and, I guess more importantly for you, help prevent "laminar squeal" and deteriation of the winding insulation on older motors.? If the latter is the case then the best option, really, is to replace the motor with a inverter duty type, but that could come at a higher cost than a sine filter.
?
Anyway good luck.
?
Ross
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Sierra Tunafish Monkeymind
Morepork
Jay