PLC's, was Re: IGBT long life at 3X rated Ip?? Re: 15kva 14.4 kV ... (fwd)

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Moderated and approved by: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Mon, 25 Dec 2006 21:20:38 EST
From: FIFTYGUY@xxxxxxx
To: tesla@xxxxxxxxxx
Subject: PLC's, was Re: IGBT long life at 3X rated Ip??  Re: 15kva 14.4 kV ...

 
In a message dated 12/25/06 9:49:18 A.M. Eastern Standard Time,  
tesla@xxxxxxxxxx writes:

>Sorry to hear this bad news.  I've used about 40 of them over  the past 
years 

>and so far, knock on wood, absolutely none of them have failed in  any 
>manner.



It may be a difference of environment. If  you're using yours in museum 
settings, they may not experience the temperature  fluctuations, vibrations, filth, 
moisture, electrical noise, and general abuse  that industrial environments 
foster. 
    
>Curious --- with all your experience Phil, what brand do you  recommend?



    I've got experience with the old Square-D Symax,  the old Cutler-Hammer, 
a couple of the OMRONs, several of the Telemecanique's  (the older, cheaper 
ones were crap), many Allen-Bradleys (Micro 1000, 1200,  1500, 500, modular 
5/01's thru 5/05's, modular 550, PLC-5's), a coupla Motorola  68000's, and even an 
ancient Giddings & Lewis. 
    I'm most comfortable with Allen-Bradley, because  IMHO their programming 
software is the best. But if you can't afford the  programming software and 
Tech Support, and you don't have to coordinate with  legacy A-B systems, I'd go 
with Siemens. 
    Siemens micros have all kinds of nice features,  like built in PID 
control blocks (as has already been mentioned here), simple  communications setup, 
face dial (for a manually adjustable analog input),  very compact size, and 
FREE software and FREE Tech Support. Their programming  manuals tend to be 
in-depth, even if less intuitive than A-B. Their Logo series  is nice if you really 
need to monitor or change programming right on the  controller, or have 
minimal text readouts for the operator. Their software also  allows you to program 
in either ladder logic or function blocks, whichever you  prefer.
    A-B has been steadily losing ground to Siemens  all over the world, 
although I'm sure there's many huge legacy users that are  going to stick with A-B.
 
-Phil LaBudde