Can anyone help with a parts source?

Hey all,

I am retroing a series 2, and I am having trouble finding a good supplier(s).
I need the following, (if you respond would you be willing to give manufacutrer and part #)?

1). a 50,000 mf or greater Cap, 150v or higher for the power supply.
2). a bleed resistor that can handle the above cap.
3). I would like to use a Thermresistor for the primary side of my transformers, to help on the inrush, but I dont know how to size them or where to get them. I have 220v on the primaries, and 70v and 40A on the secondaries.
4). bridge rectifier, 600+V, and 50+ amps
5). Has anyone found any good deals on "Glass Scales" liner encouders? I had priced them from Newell, and acurite for 0.001 resolution but the ranges for all three was from $1,300.00-$1,800.00.......rediculously out of my price range, if you don't know of any that is ok, I will go with the old tried and true servo mounted encouders.
6). Does anyone have an extra Boss 6 series 2 maintanance manual they wouldnt mind parting with. I priced one from bridgeport and they wanted 125.00, and the Manuals dot com only has them on CD, (I would prefer paper/manual). The reason is, the rear electrical cabnet is still intact, I would like the schematics on it, so I can see what I can re-use and what I can throw away. (note the entire Boss 6 control is gone).
I am currently using Rutex drives and servos/Mach3

Thanks in advance,

scott

1 thru 4 = try Digikey or Mouser - bleeder resister of 3.5K, 1/2W should suffice for cap.
5 = Bridgeprot tried the encoder f/b via linear scale on Z with their Eztrak instead of servo mounted ecoder. They found that they had to revert to servo mounted encoder when CNC'ing Z due to too much problem with oscillation due to clearance and slop. They ultmately wend to BOTH on Z (encoder and linear scale - scale for DRO in manual mode, encoder for servo f/b in auto mode)
6. The schematic will probably only give pictoral representation of the component - it will probably NOT give the actual specs (IE KVA of transformers, turns ratio, etc) outside of fuse values. You'll get as much out of reading the specs printed on any of the parts. The CD's from Machinemanuals will let you print out the pages individually - I can't get the ones I bought from them to print out anything en masse (what a PITA). NOTE: I found that the anti-copy/digital rights manager they use with their offerings did NOT want to work with any version of Adobe under ver 6.

NC Cams,

so what size thermrestor would your recommend???


scott

Sorry to report that I'm not familiar with the design vagaries for sizing a thermistor.

The commercial circuits on my machines are all merely fused.

You could always use a relay along with a digital timer circuit in conjunction with a normal resistor instead. That is what I had planned to do in my PSU design for both inrush and bleed.

You'll specifically note in the attached COMMERCIAL servo system that will run 3 large servos a conspicuous absence of relays, thermistors, digital timing circuits and other gingerbread in the DC power supply circuit.

The only "protection" for inrush involves fuses in the AC side of the transformer, that's it.

Could it be that merely properly selecting and matching components is all that is needed???? Perish the thought...

NC Cams,

Thanks for the schematic, I feel a little better about just going with fuses. I had read a few places that some where recommending thermresistors....... So, I was trying to keep up with what the latest and greatest may be, I have NO desire to fry any of my expensive stuff.........

I STILL would like to know where I could get a:

50,000 mf (or greater), 150V (or greater), Capacitor for my power supply, most of the stuff in the "Can type", caps at this volatage where around 5,500 mf or so. I did search digikey, and mouser........any other clues??? I have approximatly 42 amps on the secondary side. I am using the rule of thumb recommended by Rutex of 1,000mf per amp of power....

I would sure like some help in locating a "high" voltage, high mf Cap..... prefably the screw on terminal type.

scott

NC, Correct me if I'm wrong, but I also see an absence of any substantially large capacitors between the transformer and the servodrives either. In which case it would explain why a inrush resistor and bleed resistor are not required.

While I'm not particularly over qualified on the electrical/electronics side of things myself, I have sought advice from friends who are highly qualified and do this for a living, not to mention building some crazy stuff in their spare time like 8ft tesla coils and 600amp PWM motor controllers.

Both of them told me that with the transformer/cap/bridge psu design I had in mind I would need to limit the inrush to the capacitor otherwise I'd blow fuses, and if the fuses were rated high enough to survive this then they wouldnt help much in a serious fault condition.

Quote:

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Originally Posted by NC Cams

You'll specifically note in the attached COMMERCIAL servo system that will run 3 large servos a conspicuous absence of relays, thermistors, digital timing circuits and other gingerbread in the DC power supply circuit.

The only "protection" for inrush involves fuses in the AC side of the transformer, that's it.

Could it be that merely properly selecting and matching components is all that is needed???? Perish the thought...

---

I seem to recall reading somewhere that toriod transformers have core characteristics that cause the inrush current to be higher than that of 'conventional' transformers. That said, the power supply I built for my machine does not have a thermistor. It does have a circuit breaker.

Ken

Please, I didn't want to start a "War".

I really just need to know WHERE and WHO to get the above noted Cap, (any help and/or part numbers would be appreciated). #2). Do you who have done larger supplies have you used thermresitors and if so, how do you size them, and if you went with a differernt approach to the inrush issue and found one that WORKS in practice, please feel free to drop some advice/schematic "how to", on me.

scott

You do know that you can also mount caps in PARALLEL.

Two 140vdc 10000uf caps mounted in parallel amounts to 20,000uf or 8 totaling 80,000uF and will probably be cheaper and easier to get than 1 big 80K uF moster.

Instead of mounting 1 big one, you can mound several small ones remotely at the various driver cards. If the 3 cards will each provide say 15 amps, use the rule of thumb uF value remotely mounted at that card as opposed to a monster suitable for 45 amps to commonly draw from.

YOu can aslo limit inrush by using small gage wire as in 16 or 18 gage instead of 10 or 12 from transformer to the 3 caps. Keep in mind that the transformer windings also need ot be considered when you do the inrush limiting deal.

Yes rules of thumbs are good, but you also have to consider what each amp will draw and whether they will draw max current simutaneously. This is where the engineering part comes into play.

Part numbers and prices: no matter how you ask, Digikey and/or Mouser are your best bets.

Alternate sources would be surplus electronics component houses but this will not necessarily be easy either. Electronic Surplus in Cleveland OH has a website and caters to DIY sales - surely there are others. Simply google "surplus electronics components" and take your pick...

UKROBOTIC: there IS an unvalued cap in the DC servo circuit schematic that FU9 and FU10 feed - it has the 3.3K ohm bleeder resistor across it. FU9 and FU10 are rated at 25 amps each.

The cap is not huge electricaly - I think it is 40 or 50,000 uF but I don't recall anymore - sadly it is mouned in a way that you can NOT easily read the value on it and it is a major huge PITA to disassemble the P/S to read what the cap value is.

The servos are rated at something like 19-20 amps each if I recall.

Between the 3-6 feet of 16-18 gage interconet wire in the cabinet and anther 6-8 feet out to the servose, and the fuses, they seem to have the circuit pretty robust with regard to inrush issues.

We've never popped a DC servo fuse and we had the servos go up against the limits a number of times. BTW, we suspect that the DC servos may have never drew peak current because of soft current limits that were programmed into the sytem by the software.