Tos FN22 milling machine (Deckel clone)

[Pete.]

That is a shame.

I was rooting for your rewired 2 speed motor.

Well actually I spent some more time in it yesterday evening. It seems that it will run indefinitely at anything above 30hz, but at 20hz the drive gets warm and shuts down after a fewmnutes and at 10hz it does't run for long at all. I might persevere with it as it is for the time being but keep a spare motor handy.

During my experimenting I have also fount that the speed settings on the feeds gearbox are not correct so it loooks like I have assembled it wrong. I don't quite know how I have managed that but it's got to come back out, which handily solves the problem of the botl that won't fit.

 

[Martin-Sy]

It seems that it will run indefinitely at anything above 30hz, but at 20hz the drive gets warm and shuts down after a fewmnutes and at 10hz it does't run for long at all.

As the VFD output frequency is reduced, the output voltage should be reduced too. This is normally done by the VFD.
The reason is that the reactance of the motor windings (think of it as resistance but for AC) falls with frequency so a lower voltage (at lower frequency) is needed to produce the same current.
If the voltage remains the same as the frequency is reduced the current will rise and the windings etc will overheat.

Perhaps the VFD is not configured appropriately? Do you have a manual for it or another VFD to try the motor on?

 

[daleyd]

As the VFD output frequency is reduced, the output voltage should be reduced too. This is normally done by the VFD.
The reason is that the reactance of the motor windings (think of it as resistance but for AC) falls with frequency so a lower voltage (at lower frequency) is needed to produce the same current.
If the voltage remains the same as the frequency is reduced the current will rise and the windings etc will overheat.

Perhaps the VFD is not configured appropriately? Do you have a manual for it or another VFD to try the motor on?

I think Pete is saying the drive is getting warm, not the motor? But perhaps I have read that incorrectly

 

[Pete.]

I think Pete is saying the drive is getting warm, not the motor? But perhaps I have read that incorrectly

Yes you are correct the drive heatsink was getting warm, which was accompanied with an overcurrent trip. When it's running at 50hz the heatsink runs much moore cool.

Martin, I do have another drive but it's only rated for 1.5kw though it does display monitoring info so I may well give it a try.

 

[Hopefuldave]

Yes you are correct the drive heatsink was getting warm, which was accompanied with an overcurrent trip. When it's running at 50hz the heatsink runs much moore cool.

Martin, I do have another drive but it's only rated for 1.5kw though it does display monitoring info so I may well give it a try.

The VFD should have a couple of parameters to set, which control the voltage and current delivered to the motor - if these are wrong it'll likely be trying to deliver too much current at low frequency and getting hot: you may have checked these out already, if so any eggs your granny needs sucking?

Most important, frst to set -
Motor Current - the full-load amps rating for the motor, read off the nameplate, for a conversion/rewire from 415 to 240 multiply the 415v current by 1.6 - 1.7 will be close enough.

Base or Nominal Frequency (or something similar) - the frequency where it delivers the full output voltage (Nominal Voltage) to the motor, this should be 50Hz that the motor's designed for.
IR Compensation Voltage - this boost the voltage at low frequencies - the basic Volt/Hz graph (V/F Ratio) would start at zero, so the volts are boosted at the low end to compensate for motor winding resistance - less steep slope starting a little way up the Volts scale - for big motors this should be set pretty low as there's not much winding resistance and not much winding AC impedance at low frequencies, or even switched off.
V/F Ratio - the shape of the graph, this may be configurable - if so the maker may offer "optimised" or something similarly named, which will be the choice for variable loads.

Hope this helps, if not try the 1.5 kw VFD but it may give overcurrent trips at startup?

 

[Sergei Slovenija]

The VFD should have a couple of parameters to set, which control the voltage and current delivered to the motor - if these are wrong it'll likely be trying to deliver too much current at low frequency and getting hot: you may have checked these out already, if so any eggs your granny needs sucking?

Most important, frst to set -
Motor Current - the full-load amps rating for the motor, read off the nameplate, for a conversion/rewire from 415 to 240 multiply the 415v current by 1.6 - 1.7 will be close enough.

Base or Nominal Frequency (or something similar) - the frequency where it delivers the full output voltage (Nominal Voltage) to the motor, this should be 50Hz that the motor's designed for.
IR Compensation Voltage - this boost the voltage at low frequencies - the basic Volt/Hz graph (V/F Ratio) would start at zero, so the volts are boosted at the low end to compensate for motor winding resistance - less steep slope starting a little way up the Volts scale - for big motors this should be set pretty low as there's not much winding resistance and not much winding AC impedance at low frequencies, or even switched off.
V/F Ratio - the shape of the graph, this may be configurable - if so the maker may offer "optimised" or something similarly named, which will be the choice for variable loads.

Hope this helps, if not try the 1.5 kw VFD but it may give overcurrent trips at startup?

Or use automatic detection of electric motor characteristics in setup mode.

For most standard applications, this is sufficient (RPM while maintaining torque)

 

[Hopefuldave]

Or use automatic detection of electric motor characteristics in setup mode.

For most standard applications, this is sufficient (RPM while maintaining torque)

That *should* work, but do we know what's already configured? I hadn't looked at the book (https://www.manualsdir.com/manuals/566242/lenze-tml-flux-vector-drive-025kw-22kw.html?page=17) which shows "operating mode", probably wants C14 set to 4 for vector speed control and C48 set to 1 (calibration enabled), whch first needs C86-C91 entered from "nameplate" info, with the current adjusted for 415 to 240 rewiring. Page 22 of the book gives the commissioning steps which look simple enough (once the C86-C91 aarameters are set).

 

[Pete.]

This is the user manual I am following. I'm not using vector mode since I don't have all of the parameters to input, I have C14 set to either 0 or 2 I will have to check.

 

[Pete.]

OK so I have run this motor at 50hz for half an hour. The motor didn't rise in temperature at all but the driver got steadily warmer. At the end of 30mins I shut it down and looked it over, then went to start it again and the drive tripped with overload.

I think that the motor is simply drwing more current than a 3hp motor would normally pull. I have another flange-mount iron body motor here of the same HP and the windings in delta are 2.5-2.6 ohms. This motor is 1.8-1.9 ohms across the phases. The motor itself is showing no obvious signs of distress but I am thinking that the drive is going to be less and less happy until it lets out the smoke. I can find no setting in the drive to adjust voltage/frequency ratio.

The upshot is that I don't want to go ahead and finish comissioning the machine for the motor or drive to go pop so I'm going to fit a more modern motor.

 

[Pete.]

I got the gearbox out and stripped the top off. Had to remove the motor first as it wouldn't come out with that in place. As soon as I opened up the top I realised that I hadn't actually worked on this gearbox after all. I took the top off previously, inspected the internals, flushed out all the gunk but because everything was in such good condition I just left it alone.

The gearobx is quite complicated it has two sets of 3 sliding gears at the front which are operated by a hardened disc with grooves in each side and a set of 8 detents to select 8 gears. Then at the back there's a 1:2 reduction gear that operates another shifter to select low and high range. So, you turn the gear selector one full turn to select 8 low gears then as you go from 8th to 1st it selects a high range so you get 8 gears in low and 8 in high for 16 total. Very clever.



Somebody had been working in the gearbox previously and mis-timed the high-low selector gears, so it was throwing it into high half way through selecting the 1-8 gears which meant that instead of each gear being sequentially faster than the last it was all over the place in terms of feed rates.



They had also managed to put a slight bend in that shaft which made it tighten up every half turn, which I also took care of.

Finally the gear selection had never felt very 'positive' There is a detent plunger which screws into the casing and you can set the depth f it and lock it off with a locknut. When I got the detent wheel out I noticed that the plunger was stuck in. I loosened the locknut annd it popped out, Turns out that the locknut tightened against the rough surface of the casting so it was only contacting one side therefore when tightened down it was bending the plunger enough to make it bind and not pop out. You can see the marks on the nut on one side only.



The fix was simple, I de-greased the threads, left the locknut off and fitted the plunger with medium strength loctite. Now it's nice and snug and the gears select with a nice click.

So the gearbox is now re-assembled and back in the machine, and yes, I did remember to fit that case bolt.

 

[Seadog]

It's just like an 8-speed motorcycle gearbox, in particular the AMC box, which also use a face cam.

 

[Pete.]

This evening I've been making taper pins for the machine. I don't get many opportunities to use the taper attachment on my lathe so it was a nice diversion to set it up (even if it a royal PITA to dial in).

Metric taper pins have a taper of 1:50 so they increase 1mm in diameter for every 50mm travelled. used the DRO to set this up, simply by adjusting the angle until 50mm of z gave 1mm of X travel.



After that, cutting identical taper pins is easy



Here's the first one, going in to secure the y-axis handwheel. I have several more to make as some were damaged during dismantling, and a couple were replaced with bolts by someone previously.



Yeah, you can buy them but this is more fun

 

[minimutly]

So are you going to persuvere with the motor - perhaps get a bigger vfd, or limit the min Hz? 20Hz is a bit low for a drive motor?

 

[Pete.]

So are you going to persuvere with the motor - perhaps get a bigger vfd, or limit the min Hz? 20Hz is a bit low for a drive motor?

Nope, the motor is going.

I wasn't ever confident that the modifications I made by re-configuring the windings wouldn't have some undesirable effect. When I was a teenager I worked for a while for a company that designed and built prototype brushless DC motors. My job was bulding lamination stacks, insulating them with plastic coating, installing the windings and encapsulating them. Being only 17 I didn't understand a lot of what I was doing just followed an instruction sheet but I do remember that there was a very clever guy there with some fancy software on a PC and he would sometimes explain why I was making stacks with 1 more lamination, or slightly different width slits etc and I understand that even subtle changes can have a large effect on a motor, and I made huge changes. I don't know what the problem is that's causing the VFD to heat up but I do know that it could be any of a number of things. I think it's fruitless to invest any more time into a part that's hidden out of sight within the machine just for originality's sake when I can just buy a modern replacement with modern vfd-friendly insulation. It was an interesting idea but for me it just didn't work.

I will fit a different motor and think about the optioon of getting this one re-wound as a straight 4-pole motor by someone who knows what they are doing.

 

[RichardM]

This evening I've been making taper pins for the machine. I don't get many opportunities to use the taper attachment on my lathe so it was a nice diversion to set it up (even if it a royal PITA to dial in).

Metric taper pins have a taper of 1:50 so they increase 1mm in diameter for every 50mm travelled. used the DRO to set this up, simply by adjusting the angle until 50mm of z gave 1mm of X travel.

View attachment 420468

After that, cutting identical taper pins is easy

View attachment 420469

Here's the first one, going in to secure the y-axis handwheel. I have several more to make as some were damaged during dismantling, and a couple were replaced with bolts by someone previously.

View attachment 420470

Yeah, you can buy them but this is more fun

Are you going to tap the ends so the blind ones are easily removable in the future?

 

[Pete.]

Are you going to tap the ends so the blind ones are easily removable in the future?

None are in blind holes otherwise yes I would.

 

[Pete.]

Well, this motor is giving me a rollercoaster ride and no mistake. In the words of Brian Stimpson "I can take the despair it's the hope I can't stand".

I wanted to test the functions of the feeds gearbox after rebuilding and re-fitting it so I put the motor back in and wired it up to the VFD. This time however I went through the whole printed-off parameter list and checked/adjusted/noted down the settings, and during this excersise I found out that you CAN monitor Output Frequency, Motor Voltage, DC bus voltage, Motor Current and Controller Load using parameters C50-C56. I also realised that stuff labelled as "will be automatically programmed" can be manually entered.

I also found I had set C16 'V Boost optimisation' to 30 when the default is 0. I don't know why that was at 30 it's possible I thought I was adjusting min frequency because it's the only 30 setting I remember putting in.

So after inputting some motor data fro the plate (some as a best-guess), adjusting some parameters and monitoring motor amps/controller load I now have it so I can run it at any speed right down to 10hz without tripping out the controller, and the high-pitched whistle which was there at any frequency below 20hz is completely gone, and the motor starts more smoothly too. It draws the most amps (8) at 45hz but only 6.x at 50 hz and it drops off into th 3.xamps as the frequency gets higher. Down at 20-30hz it's drawing about 6a per phase which is about 65% load on the controller. It's a shame I have no comparative data from before when it was getting hot but I made all the initial parameter changes before discovering that I could monitor current and load.

The only fly in the ointment is I can generate a DC bus overvolt fault up around 80hz if I adjust the speed up and down too quickly in that range. I've got a lot more testing to do I'm going to adjust the cosine phi setting up and down a bit and see what effect that has, adjust the v-boost setting according to the note attached and I have yet to adjust slip compensation which I'm expecting to have a measurable effect but that will be much later when I can put some load on the motor.

I'm still going to get a modern motor because there's still no telling if this one is going to work out, and even if the motor's 1960's insulation is going to cope long-term with the VFD transients, but right now, it's working well enough that it can stay put.

BTW I did test the function of the feeds gearbox and now all 16 feed rates are working exactly as they should be.

 

[Brad93]

Well, this motor is giving me a rollercoaster ride and no mistake. In the words of Brian Stimpson "I can take the despair it's the hope I can't stand".

I wanted to test the functions of the feeds gearbox after rebuilding and re-fitting it so I put the motor back in and wired it up to the VFD. This time however I went through the whole printed-off parameter list and checked/adjusted/noted down the settings, and during this excersise I found out that you CAN monitor Output Frequency, Motor Voltage, DC bus voltage, Motor Current and Controller Load using parameters C50-C56. I also realised that stuff labelled as "will be automatically programmed" can be manually entered.

View attachment 420590

I also found I had set C16 'V Boost optimisation' to 30 when the default is 0. I don't know why that was at 30 it's possible I thought I was adjusting min frequency because it's the only 30 setting I remember putting in.

View attachment 420591

So after inputting some motor data fro the plate (some as a best-guess), adjusting some parameters and monitoring motor amps/controller load I now have it so I can run it at any speed right down to 10hz without tripping out the controller, and the high-pitched whistle which was there at any frequency below 20hz is completely gone, and the motor starts more smoothly too. It draws the most amps (8) at 45hz but only 6.x at 50 hz and it drops off into th 3.xamps as the frequency gets higher. Down at 20-30hz it's drawing about 6a per phase which is about 65% load on the controller. It's a shame I have no comparative data from before when it was getting hot but I made all the initial parameter changes before discovering that I could monitor current and load.

The only fly in the ointment is I can generate a DC bus overvolt fault up around 80hz if I adjust the speed up and down too quickly in that range. I've got a lot more testing to do I'm going to adjust the cosine phi setting up and down a bit and see what effect that has, adjust the v-boost setting according to the note attached and I have yet to adjust slip compensation which I'm expecting to have a measurable effect but that will be much later when I can put some load on the motor.

I'm still going to get a modern motor because there's still no telling if this one is going to work out, and even if the motor's 1960's insulation is going to cope long-term with the VFD transients, but right now, it's working well enough that it can stay put.

BTW I did test the function of the feeds gearbox and now all 16 feed rates are working exactly as they should be.

If you want to bring the motor over and run it on pure mains three phase you're more than welcome

 

[Pete.]

If you want to bring the motor over and run it on pure mains three phase you're more than welcome

Can't do that it's permanently wired for 240v 3 phase, but thanks for the offer

 

[Hopefuldave]

Well, this motor is giving me a rollercoaster ride and no mistake. In the words of Brian Stimpson "I can take the despair it's the hope I can't stand".

I wanted to test the functions of the feeds gearbox after rebuilding and re-fitting it so I put the motor back in and wired it up to the VFD. This time however I went through the whole printed-off parameter list and checked/adjusted/noted down the settings, and during this excersise I found out that you CAN monitor Output Frequency, Motor Voltage, DC bus voltage, Motor Current and Controller Load using parameters C50-C56. I also realised that stuff labelled as "will be automatically programmed" can be manually entered.

View attachment 420590

I also found I had set C16 'V Boost optimisation' to 30 when the default is 0. I don't know why that was at 30 it's possible I thought I was adjusting min frequency because it's the only 30 setting I remember putting in.

View attachment 420591

So after inputting some motor data fro the plate (some as a best-guess), adjusting some parameters and monitoring motor amps/controller load I now have it so I can run it at any speed right down to 10hz without tripping out the controller, and the high-pitched whistle which was there at any frequency below 20hz is completely gone, and the motor starts more smoothly too. It draws the most amps (8) at 45hz but only 6.x at 50 hz and it drops off into th 3.xamps as the frequency gets higher. Down at 20-30hz it's drawing about 6a per phase which is about 65% load on the controller. It's a shame I have no comparative data from before when it was getting hot but I made all the initial parameter changes before discovering that I could monitor current and load.

The only fly in the ointment is I can generate a DC bus overvolt fault up around 80hz if I adjust the speed up and down too quickly in that range. I've got a lot more testing to do I'm going to adjust the cosine phi setting up and down a bit and see what effect that has, adjust the v-boost setting according to the note attached and I have yet to adjust slip compensation which I'm expecting to have a measurable effect but that will be much later when I can put some load on the motor.

I'm still going to get a modern motor because there's still no telling if this one is going to work out, and even if the motor's 1960's insulation is going to cope long-term with the VFD transients, but right now, it's working well enough that it can stay put.

BTW I did test the function of the feeds gearbox and now all 16 feed rates are working exactly as they should be.

The Bus Overvoltage will be happening when decelerating, the motor acts as a generator and tries to dump all the stored energy in spinning motor, pulleys, gears, shafts etc back into the VFD - this all charges the bus capacitors beyond normal voltage and that's what it's complaining about. Either you can add a braking resistor* (or if you're unlucky it may need a brake controller wiht electronics in) OR.. not slow down so fast!


* if it's just a resistor required, those nice Chinese gents inhabiting EvilBay do them very cheaply, or a pair of oven elements wired in series will work - check the book of mistranslated words to see.