Re: 180 BPS synch? (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 16 Jul 2007 17:51:50 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: 180 BPS synch? (fwd)

Yes, Phil, your right, it's 4-20mA. Thanks for the correction. I'm 
probably going to replace my Altivar 31 with a brand new ABB 3 HP drive 
I have sitting on my desk. Something I've been wanting to play with but 
just haven't got around to it.

Take care,
Bart

Tesla list wrote:

>---------- Forwarded message ----------
>Date: Sat, 14 Jul 2007 16:25:37 EDT
>From: FIFTYGUY@xxxxxxx
>To: tesla@xxxxxxxxxx
>Subject: Re: 180 BPS synch? (fwd)
>
> 
> 
>In a message dated 7/14/07 9:05:52 A.M. Eastern Daylight Time,  
>tesla@xxxxxxxxxx writes:
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>>The VFD itself is wired up to accept a 0 to 10mA signal that  controls 
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>>the speed from 0 to 500 Hz.
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>    Shouldn't that be 4-20mA? One of the advantages  of a 4-20mA current loop 
>signal is to avoid the noise of zero mA meaning  "zero signal". Hence the 
>minimum 4 mA...
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>>I use an Altivar 31 VFD by Telemecanique. Telemecanique was once  known 
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>>as "not the greatest of VFDs". That has changed in the past 4  years. The 
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>>company actually was revamped. Nowadays, their drives are probably  the 
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>>easiest to use and are now very reliable. Especially the Altivar 31  
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>>series (versus the old Altivar 28 which was pure Telemecanique of  old).
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>Now that I've finished laughing so hard that I  had to pick myself up the 
>floor, I find myself wondering if you're actually  *serious*! 
>    I finished replacing the fourth ATV 31 drive  (from 2kW to 15kW) in a 
>brand new installation. Four drives in less than a  year of operation? I 
>cannibalized all of them. Most failed due to the "brick"  having bad connections. They 
>went to a design that clamps down, so  the brick leads spring against pads on 
>the circuit board, instead of  bolting or soldering to connections to it. One 
>had a blown input rectifier,  which when replaced allowed control and display 
>power but the output was still  dead as a doornail (even though the display 
>told me it was running  OK).
>    "Easiest to use"? Are you kidding??? Where do I  start... no local keypad 
>jog function, no local/remote key on keypad, no  easy-to-replace keypad 
>(without disassembling the drive), no parameter storage  in keypad, no built-in 
>line or load reactors, no provision for external  powering/switching of cooling 
>fan, no built-in macros for common user  applications, a *very* primitive LED 
>display (three letter codes derived from  7-segment LED's, and the codes are in 
>French/IEC abbreviations), no standard  provision for encoder interface, 
>included hard copy manual is minimal.
>    IMHO the only thing I like about Telemecanique  is their cable safety 
>switches (which they pioneered). If it's Tele, you name  it, I've worked with it. 
>I tried to get an Alitvar 41 (IIRC) which was a very  cost-effective drive. I 
>needed a 20kW for a fan application, and they  don't make 31's bigger than 
>15kW. We got a great price break from our vendor  on Tele crap, and I wanted to 
>keep things standardized. But apparently  although they list that product on 
>the Tele website, they only offer it in  Europe.
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>>when it comes to motor control, 3-phase is industry standard  and VFD's are 
>>their industry standard control module.
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>    Depends very much on the industry! I've seen two  brand-new printing 
>presses built and installed at two different local  factories in the last two 
>years that both had 40+ HP *DC* motors as the main  drive! I've worked on all 
>brands and vintages of those things, and can say  with no reservation that a DC 
>motor is a complete waste (and liability!) for  that application. But it seems 
>that's all the "old" engineers will trust.  Shame, I've seen tiny AC motors run 
>big presses, and spec'ed and installed a  big 60 HP AC motor and C-H SV9000 
>drive on an old press. Both run  flawlessly...
>    Some places still use a lot of single phase  motors for smaller loads and 
>machine automation. Steppers are popular for  slow-speed positioners. On that 
>note, I've seen plenty of brand-new DC servos  on new equipment. 
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>>In motor control, Allen Bradley is still top of line for  VFD's.
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>    Are you trying to kill me with laughter, Bart?  :)
>    Their new Powerflex line is interesting, but you  can keep your 1305's 
>and 1336's. Too many problems with those in too many  applications to list here.
>    OTOH, A-B is the "Dark Side" of Rockwell  Automation. Reliance has always 
>made very tough stuff. I've seen old Reliance  drives, of all types, 
>soldiering on long after they've become obsolete. They  still seem to make a very 
>tough AC drive with a good reputation. I wish I've  had more than a passing chance 
>to work with modern Reliance AC drives, so I  could confirm my good 
>impression.
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>>But the others now are right there with them in capability. The  main 
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>difference is that industries are >tied into a particular breed by the  code they 
>write. It would be an expensive task 
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>>to change over to something else. So, they stick with what they are  
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>>familiar with. I do the same. I understand that situation  completely.
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>    True, and nothing can make or break you like  being tied to a particular 
>brand by nothing more than a salesperson or  engineer's inconsiderate 
>preference (usually a kickback).   
> 
>  IMHO the Cutler-Hammer SV(X)9000 drives have given me the best  luck over 
>the long run, although the manual is a bit difficult in places.  Sumitomo 
>drives were built like a battleship. ABB makes a very nice and  affordable AC 
>drive, but their DC drives are a nightmare. Baldor drives are very  user-friendly, 
>but always seem to have issues with control power supplies.  Eurotherm drives 
>are *way* over-engineered for programming options (difficult to  commission), 
>and not robust enough. Hitachi and Mitsubishi AC drives are about  the 
>cheapest I've found, and seem to do fine. 
> 
>-Phil LaBudde
>Center for the Advanced Study of Ballistic  Improbabilities
>
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>
>************************************** Get a sneak peak of the all-new AOL at 
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