selecting the right hardware

Hi guys, 

i'm renewing a control panael for a large packhouse, simple stuff essentially just 50 odd conveyors in 5 groups that need to come on at certain times

my intention is to do away with all the contactors and have a s71500 cpu with 5 et200sp slave stations, each station will represent a group of conveyors and control the motors via et200sp motor starters

firstly, does anyone have any insight into this kind of topology on why it might be a good/bad idea? secondly how can select the right cpu

cheers gents

IMHO using specialized IOs instead of standard IOs and bunch of additional devices reduces cabling. So less errors thus faster commissioning.

Selecting CPU is always tricky without some experience. I'd go for the weakest one at first. Yes, you must have some hardware to start with. Then after having software ready and its cycle time measured, it can be predicted which CPU to use in case required cycle time is exceeded.

Hi robbie c,

In my opinion, such a structure should work. You should first check if the ET 200SP motor modules fit your conveyor motors. You should also consider the need for fail-safe modules instead of standard modules. If you are already using ET 200SP and it is a simple application, you might also consider the CPU 1510SP-1 PN (or CPU1510SP F-1 PN). You can use this CPU instead of an ET 200SP interface module, which will reduce the cost.

Did you know that the Siemens TIA Selection Tool is a free tool for planning your application?

Kind regards
Stefan

thats my thinking, using single supply bus i/o instead of the amount of contactors and relays i can reduce cables in this panel by 70% roughly

also this is one of those rare occasions where money isn't really an issue so i think i'll select something i know to be fairly powerful at least then i'll have scope to increase the system later 

thinking 1516-cpn

indeed i was thinking the cpu1510 wich i've used before but with the extra slave stations and potential for expanding the system i was thinking something slightly more powerful 1516 perhaps 

also i'm considering throwing out the safety relay and installing fail safe cpu with fail safe modules instead 

as for motor starters i can confirm they suit my motors, i appreciate the insight!

3Φ Contactor accessory: busbar x2 / x3 / x4 / x5 greatly reduce the wiring INTO contactors on a single DIN rail.

However, you often end up adding contactor monitoring contact blocks, and for motors, you often need MSP (thermal overload / isolators) upstream of the contactor. In fact, Siemens noticed and offers the combo overload / monitor / contactor as a single part # - as well as the busbar accessory.

Just another way to think about it.  Also, when a single contactor fails, you lose control over one motor.  If you lose any component that takes out the ET200 motor controller system, you very well may lose control over all the motors.

Optimal selection is not a "professional or personal preference".  It's whatever is appropriate for a given project or set of projects of a given type.

If a system can tolerate a small number of motor controls to be inoperative (while awaiting parts or during troubleshooting / repair), contactors may be preferrred.

If a system is 100% or 0%, a more centralized control scheme - like you are investigating - may be preferred.

robbie c

thats my thinking, using single supply bus i/o instead of the amount of contactors and relays i can reduce cables in this panel by 70% roughly

also this is one of those rare occasions where money isn't really an issue so i think i'll select something i know to be fairly powerful at least then i'll have scope to increase the system later 

thinking 1516-cpn

thanks einstein i can appreicate what you're saying.

given the ease of control and amount of integrated feedback i can get from the et200sp motor starter i think i'm going to go in this direction and just make sure we are well stocked with spare interface modules and MS parts!