Designing a new system. ISO suggestions

Cookz615

Member
Join Date
Feb 2017
Location
tennessee
Posts
18
Hello,

I have been tasked to design a new control scheme for a system we have in our plant. My plan is to use all AB controls, which is a requirement, by the facility. I will be running 10 VFD's that will handle recirculation pumps. My plan is to use PF 755"s. I am also going to be running quite a bit of remote IO. I will be setting up a DLR topology for most of it. One thing I am unsure of is how to choose which control logix processor I'm going to use. To be honest with you I've never gotten the opportunity to pick. I figured I would reach out to you guy's for some insight and guidance. Any suggestions or advice would be appreciated. Thanks!
 
Processor really just depends on how much logic you need to run your process.

1756-L8x are the newest, vary in memory size, but you may not need that much horsepower. CompactLogix is quite capable. ControlLogix gives you more flexibility, especially with communications should you need additional network interfaces, perhaps a DeviceNet card, DHRIO (legacy) and can handle very large complex processes. If your process is pretty localized I would be surprised if you actually needed a ControlLogix.

Layout all the remote IO nodes you need, all the IO you need, and all the logical programs you believe you will need. The user manual has some information on calculating memory needs. Also, include what your budget is, money to be saved here if you quoted/budgeted a 1756-L85 and can get away with something much smaller.
 
What is the motor voltage?
how far is it from the vfd's to the motors?

if you are using 440 volts, and the distance from the vfd to the motor is more than 50ft(I think), you will need load reactors, maybe even line reactors.

you also need to use shielded vfd cable in the panel and motor wiring to reduce noise.

you need to calculate heat and may need an a/c unit.

be aware of NFPA 70 (nec), 70e (are flash), 79 electrical standard for industrial machinery. if this is for a classified area, you have special rules.

main power in one section with the contactors and power bus, vfd's in another section, controls in another section, use finger safe items everywhere.

regards,
james
 
One thing to keep in mind if you do decided to go with the ControlLogix side of things is that the L8's are only very slightly more expensive than the L7's ($200 list price between L83 and and L73), but the L8 saves you the cost of an additional ethernet card since it has a built in ethernet port. So as a package the L8 saves you about $3k over an L7 with and EN2T ethernet card, and in my experience so far the L8 has a scan time about 1/10th the scan time of the L7.

-Benaiah
 
Also keep in mind that if you go with a L8x, you would still need to buy a EN2TR if you want to use DLR, the L8x only has a single port.
 
Also keep in mind that if you go with a L8x, you would still need to buy a EN2TR if you want to use DLR, the L8x only has a single port.

Good point. You also need to stay with the L7 for now if you want a safety controller. The L8's with safety are coming out later this year (supposedly).

-Benaiah
 
Huge thanks to guy's for all of the insight. I am pretty green to this side of things. This is actually the first project I get to lay out from the ground up. You guys insights are really helpful. I will look into and take into consideration all of these suggestions. I will be sure and repost how things go. Again, THANK YOU!!!
 

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