gmane.linux.distributions.emc.user

Re: Commutating Reactor

gene heskett — 2012-05-25T13:13:28

On Friday, May 25, 2012 09:04:33 AM John Thornton did opine:


John;  How far away are you from an actual 3 phase power source?  Might the 
one time construction costs the power peddlers want to bring it to you be 
competitive when spread out over the years?  In my own case, it would be 
about a 3 block run out here in this cul-de-sac about 50 yards inside the 
city limits.


Cheers, Gene

Re: Commutating Reactor

John Thornton — 2012-05-25T13:04:42

Totally missed the second paragraph... no I've not checked to see if it 
works on single phase. I'll get the model number in a bit. If you can 
decipher the Siemens documents my hat is off to you sir as it is really 
confusing to me.

John

On 5/25/2012 6:45 AM, andy pugh wrote:

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Re: Commutating Reactor

John Thornton — 2012-05-25T13:02:30

I sent perfect phase an email with a bunch of questions so we will see 
what they say. In the mean time I'll try the Fitch tuning method for the 
rotary phase converter.

John

On 5/25/2012 6:45 AM, andy pugh wrote:

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Re: Custom Encoders

andy pugh — 2012-05-25T12:35:35

The encoder needs a contrast between shiny and not-shiny. A hole is
not-shiny enough (and anything behind the hole is out of focus and
invisible)

Mounting is part of the reason I need a custom encoder, it has little
fingers to fit between the rotor magnets.

Re: Custom Encoders

John Thornton — 2012-05-25T12:24:33

That's a neat solution... how will you mount the disk? I assume the disk 
is a mask for a dark background?

John

On 5/25/2012 7:09 AM, andy pugh wrote:

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Custom Encoders

andy pugh — 2012-05-25T12:09:51

I have built a motor.
Internal space is quite tight, so I am using the Avago AEDR8340K
encoder detector
http://uk.rs-online.com/web/p/rotary-encoders/7160604P/
(Also available from Mouser etc). This is a 3mm x 5mm two-channel
quadrature detector. TTL output wires direct to Mesa / Parport / Pico.
I initially tried to make my own encoder disc by etch-resisting (with
a pen) some polished aluminium then etching with FeCl
http://youtu.be/c1zCG-uPaoM
This almost worked, but there was a problem with missed/multiple
counts. The AEDR application notes make it clear that it really can't
be expected to work right at anyhting other than native resolution. In
the case of the "K" variant that is 75lpi, which means 0.15mm (0.006")
slot width. i got a quote for Photochemical etching from Photofab
which was rather reasonable (£4 each) but with a £100 setup charge and
a 25 minimum quantity (s £200+ all in).
I then found that within half a mile of my house is a company who
specialise in laser cutting solder stencils for PCB assembly. They
have a machine with a 25um beam width optimised for cutting stainless
sheet:
www.sparkslaser.com
They are doing me 2 different parts for £50 (and have already given me
one fully-finished part as a "sample", which tested with 100% success
this lunchtime.

I will get pictures later.

This seems like quite an easy way to make a spindle encoder, for
example, where off-the-shelf encoders tend to have too small a bore. I
imagine that if Basildon has a stencil-making business, then they must
be numerous.

Re: Commutating Reactor

John Thornton — 2012-05-25T12:07:20

I have 2 10hp and 1 15hp motors and enough parts to make 3 rotary phase 
converters. Total capital invested is in the $750-$1000 range. That size 
motor used is cheap around here. As for turning it back into cash that 
would be more difficult as there is not much demand for phase converters 
that I know of in that size range but you can never tell I might be able 
to sell one or two for $500 or so.

I agree it would be a cleaner solution and I'm very tempted at this 
point. Without much research so far I assume I would need the $4.7k 
model 55 amp model. Further testing is needed... I seldom run more than 
one CNC machine at a time and almost never run the 3-phase manual lathe 
at the same time. So the $3.1k model may fill my needs with 30 amps.

The manual lathe and the CNC lathe are very happy running on a phase 
converter but I'd rather not have the noise of the idler motor in the 
shop as they seem to be a bit noisy... and I'm rambling on now just 
trying to make some sense.

I need to open a dialog with phase technologies and see what they say.

Just reading the PT instructions they do show that they take the single 
phase and convert it to DC then back to AC but only do that for one leg...

http://www.phaseperfect.com/files/op_inst_pt.pdf

A snippet of the manual

The input module takes power from the input lines and charges a DC bus. 
The output module then draws power
from the DC bus to generate an AC voltage referenced to L2 of the input.

L1 and L2 of the single-phase input pass directly through the phase 
converter to provide two legs of the threephase
output. A manufactured phase is combined with the two input legs to 
produce three-phase output power.
Hence, the three-phase output voltage will be equal to the single-phase 
input voltage (e.g. a 240 VAC
single-phase input will produce 240 VAC three-phase output).

The three-phase output is delta configured. While the phase-to-phase 
voltages are equal, the phase-to-ground
voltages are not equal. Phase-to-ground voltage for both T1 and T2 
should be approximately 120V. Phase-toground
for T3 should be approximately 208V. For three-phase loads that are 
designed for delta connection, the
load derives its voltage phase-to-phase, so the phase-to-ground voltage 
should not affect the operation of the
equipment. If the connected load has a neutral connection and requires 
wye configured power, the output
of the phase converter must be passed through a delta-to-wye isolation 
transformer before connection to
the load.

Thanks
John

On 5/25/2012 6:45 AM, andy pugh wrote:

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Re: Commutating Reactor

andy pugh — 2012-05-25T11:45:02

It might be a better / cleaner solution, though. And it might release
some capital if you can sell your existing rotary convertors?
How much other 3-phase kit do you have?

I have found a lot of documentation on the Siemens site:
http://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&siteid=cseus&aktprim=0&extranet=standard&viewreg=WW&objid=10804939&treeLang=en
Which infeed unit do you have? Have you checked to see if it can be
configured for single-phase operation?
(it looks like SimoDrive is the drive part, and the Dc converter will
be something else)

Re: Commutating Reactor

John Thornton — 2012-05-25T11:15:26

Do you have an example circuit of this that I can drool over?

Thanks
John

On 5/24/2012 11:50 PM, Erik Christiansen wrote:

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Re: Commutating Reactor

John Thornton — 2012-05-25T11:13:16

I can get the model number in a bit but it is a dual trace scope with 
storage. The second trace would show up as a horz line so I'm sure I had 
some knob in the wrong spot. I tried to follow the instructions but 
could not find where it showed how to make a dual trace. It would be 
nice to compaire at least one line phase to the generated phase.

Thanks
John

On 5/24/2012 9:17 PM, gene heskett wrote:

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Re: Commutating Reactor

John Thornton — 2012-05-25T11:08:28

Jon,

Thanks for that lead, a quick search and I found a 6 page instructions 
for making a 10hp and tuning it up as well. He goes into great detail 
and makes it simple to try. I see his start circuit is a bit different 
than mine as he uses a control transformer but I have a large box of 
phase converter parts so I can duplicate the drawing exactly.

http://www.practicalmachinist.com/FitchWConverter.pdf

I'll probley wire up the 10hp this week end and give that a shot before 
running off to buy the generator.

Thanks
John

On 5/24/2012 8:42 PM, Jon Elson wrote:

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Re: Commutating Reactor

John Thornton — 2012-05-25T10:56:41

It's hard to say but I "think" the 15hp motor worked the best. I've been 
running and trying different things for a 1 1/2 years so my memory is a 
bit clouded on exactly how it worked or didn't work. I do know at one 
time my workaround was to ramp up the spindle from 2k to 6k and it ran 
like that and that was on one of the 10hp motors.

Do you think adding a line reactor after the rotary phase converter 
would help in any way? I can get a 3 phase 20hp one for $150 so it is 
cheap enough to try if anyone thinks it might help in any way.

http://www.automationdirect.com/adc/Shopping/Catalog/Drives/GS2_%28115_-z-_230_-z-_460_-z-_575_VAC_V-z-Hz_Control%29/AC_Line_Reactors/LR-2020

Taking the reactor out of the VMC sure made it worse... and the scope 
trace looked horrible jagged.

Just to refresh the circuit is: [ stuff in brackets ] is inside the machine.

phase converter > [ step up transformer > commutating reactor > infeed 
unit (power supply)]
On 5/24/2012 8:37 PM, Jon Elson wrote:

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Re: Commutating Reactor

John Thornton — 2012-05-25T10:42:27

Thanks for the price sheet. That is over double what I can get a diesel 
generator for around here.

John

On 5/24/2012 3:54 PM, Dave wrote:

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Re: Commutating Reactor

Dave Caroline — 2012-05-25T05:01:36

Remember this is an LC network running at some amps and the current is
not in phase with the voltage.
so switching at zero volts might mean very high currents at that instant

Dave Caroline

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Re: Commutating Reactor

Erik Christiansen — 2012-05-25T04:50:35

No, not really that hard. There is no practical reason to allow
substantially different voltages on the capacitors, if fast switches are
used, as suggested. It takes only a transistor, a diode, and a resistor
to add a zero crossing detector to the micro.¹ Now it can switch the
capacitors in and out at near-zero voltage, twice per mains cycle, if
necessary. (Alternatively, before relying on zero crossing detection
built into the SSRs, I'd like to read the datasheet, and check them out.)

Erik

¹ Ideally connected to an interrupt input. (And then drive some triacs
  to switch the capacitors. It'll be cheaper than SSRs.)

Re: Need Help from U.S. Users & Companies - APT (Automatically Programmed Tools)

Matt Shaver — 2012-05-25T02:58:28

On Thu, 24 May 2012 10:28:03 -0400
"Kent A. Reed" <kentallanreed-Re5JQEeQqe8AvxtiuMwx3w< at >public.gmane.org> wrote:


I haven't seen much of it, but I suspect that it's a lot better and
AFAIK, all in Fortran. I had the same sort of reaction to the IBM360
version myself, not to disparage in any way the exceptional work done by
Brent Muller to make it run on Linux. The motivation for trying to get
a later version is to supply guys like you & Brent with a better
starting point from which to proceed.

Thanks,
Matt

P.S. All of the user stories have been very useful! Additional "use
cases" are desired and appreciated!

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Re: Commutating Reactor

gene heskett — 2012-05-25T02:17:05

On Thursday, May 24, 2012 09:59:35 PM John Thornton did opine:

I hadn't considered that aspect of it John, but I suspect you are 99.44% 
correct.


Not surprising.  The tektronix that existed in the 60's, was gone by the 
late 70's and its all been downhill since (IMO).

Most tek scopes are at least dual trace, is that one a single trace?

There are even 4 trace scopes out there, Hitachi makes a fine one.

But in a pinch, set the camera on a tripod, hook the scope up, triggered by 
its internal line sample, then adjust the sweep speed to show about 1.5 
cycles and take a pix.  Move the probe to the next phase and take a pix, 
and finally to the 3rd phase and take another picture.  Then disconnect the 
probe as its not made for continuous duty at those voltages.

Then, using the scopes face bezel as the registration, merge all 3 shots 
into one common image.  Since the scope is synched to its own supply, the 
phase differences can be measured from this merged image.  My guess is that 
the positive going slope of the 3 traces will not be equally spaced 
horizontally.  And it should be.

Cheers, Gene

Re: Flash hole drill sizes for BP with 209 ignition?

gene heskett — 2012-05-25T01:51:41

On Thursday, May 24, 2012 09:49:28 PM John Thornton did opine:


PLease ignore me John, and thanks for not biting back, I was really tired 
when I wrote that.  My apologies.

Cheers, Gene

Re: Commutating Reactor

Jon Elson — 2012-05-25T01:42:06

Ummm hmmm, not quite as bad as I expected, but you probably need some
of the options, so even the smallest would end up at $4k.  Maybe you could
provide your own input reactor for a lot less than $900.  And, there's no
guarantee this would fix the problem, either!

There used to be a guy, Fitch Williams, on rec.crafts.metalworking that was
the expert on rotary converter tuning.  He had a technique for getting the
L-L variation down to +/- 2 V or so on almost every unit.  You might search
for some of his write-ups on this.

Jon

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Re: Commutating Reactor

Jon Elson — 2012-05-25T01:37:24

Did any of these motors make a difference (better or worse)?

Jon

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Re: Commutating Reactor

Jon Elson — 2012-05-25T01:34:57

Got a price on those?  better be sitting down when you ask!

Jon

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