Auto pump control

Hi,

I am using a Micrologix 1200 to control pumps and need a little help in writting the code for it.

Basically the operation is like this.
We have 5 pumps.
One pump needs to be running constant to keep a certain pressure of water.
When the pressure drops I need an assist pump coming on.
If the pressure is still too low a second assist comes on, and still low a third assist comes on.
I can't run the 5 pumps together.
Also, I would like to rotate the duty on these pumps automatically.

I have writen the code for the pressure drops, but the rest i am struggling a little with.

Any help would be great.

Thanks, Conor

Fuzzy logic this is a prime example instead of level your using pressure. So take your pressure readings run less than equal statements when the pressure goes below a specified point activate the next pump in sequence one way for the rotation is to assign each pump a bit value = to the output and you could use the SQO statement to control which ones come on at given points Post what you have thus far and we will be glad to help edit forgot to add you will probably need to look up the status bits related to the RTC for your time periods I beleive the micrologix has a real time clock

Hi,

I have attached the as zip of the rss file of what I have so far

your version of RS logix appears to be incompatible with mine as I cannot open this file can you print it to a PDF? You can use the PDF995 printer emulation program just type pdf995 on google and it will pull the site to download the utility. Also are you familiar with the SQO instruction or would you prefer a different method?

also find out if your Micrologix 1200 has a 1762-RTC installe with it you are probably going to need this to rotate the duty. Particularly if your concerned about equal time on each pump as the primary.

http://literature.rockwellautomation.com/idc/groups/literature/documents/wp/1764-wp002_-en-e.pdf

here is the instruction set for your controller in case you don't have it

in regards to pump rotation use the S:40 or RTC.0.hr instruction to keep track of the running hours when it reaches a set number of hours via a counter/compare instructions go to the next pump as primary. If you wish to use the SQO use the primary pump number to set the start point on the SQO statement. so you can have a truth table similar to the following keep in mind I'm only showing the bit pattern under display special you will still need to set the mask and the stepping instructions to control the SQO placement.

to avoid confusion the outputs read right to left not left to right

00001 pump one primary
00011 pump one pump two
00111 pump one pump two pump three

00010 pump 2 primary
00110 pump 2 and pump 3
01110 pump 2 and pump 3 and pump4

00100 p3 primary
01100 p3 p4
11100 p3 p4 p5

01000 p4 primary
11000 p4 p5
11001 p4 p5 p1

10000 p5 primary
10001 p5 and p1
10011 p5 p1 p2

this should get you started tie in the pressure values to control you R statemants needed by the SQO statement and the pump rotation use the SQO start position

here is an example of two groups using straight I/O switch between groups I went with the pressure as straight inputs as if there were three sensors that close when a specific pressure is reached you can easily change this by implementing your pressure controls. This is merely an example without the SQO working on the reset aspects of the SQO method Ie what to do if you test the pressure and find its gone too high and want to reverse the sequence for that reason the method here may be better suited for you

I just realized my descriptors are a little confusing it should be mid low pressure instead of mid pressure and extreme low pressure instead of high pressure. I would also have a timer to prevent the pumps from chattering on/off and a safety rung to turn off all pumps if the pressure gets too high. I also have to add some timers and XIC statements to prevent a jump from 1 punmp on to all three on before you see if two pumps can reach pressure in a reasonable amount of time

Thanks Mordred. I will check it out in work in the morning.

Hello Conor,

You have gone the PLC way..but this is a standard application for all Altivar 61 (schneider electric product) variable speed drives.

They come with an option of multi-pump card, which does exactly what you are planning.

In case you have already bought the PLC, then go ahead, but for future projects VSd with multipump card is a good option.

I have done more than 25 quadruplex skids (with VSD) for constant pressure control and thay are working fine.

Cheers.

look through this one it has less mistakes in it keep in mind I'm writing this only to demonstrate one or the other method the other method I'll try to work on today. My time doing this is limited so the programs may be missing some things I did not think of

Pdf file attached.

Hi,

I have attached the pdf file (thanks Mordred for download).

Can someone read and review please.

Thanks, Conor

rung 0001 has no input you will want to add a start button and a stop button use that to control your always on bit. I see you are going to install a maintenance selector switch for pump availability which is a good idea. However if a pump is not available in a group you may want some logic to prevent pump groups that use it from activating. Will make an interesting truth table LOL. How are you planning on doing the pump running feedback ? I'm not sure what the counters are for however. Seems to add unnecessary confusion and I don't beleive you wil need counters unless I'm missing something the 4.5 min timers is a good idea however. So am I correct in that you have three pressure sensors? each set at a different value or is it one sensor with a pressure return reading via analog of ascii?

mordred said:

rung 0001 has no input you will want to add a start button and a stop button use that to control your always on bit. I see you are going to install a maintenance selector switch for pump availability which is a good idea. However if a pump is not available in a group you may want some logic to prevent pump groups that use it from activating. Will make an interesting truth table LOL. How are you planning on doing the pump running feedback ? I'm not sure what the counters are for however. Seems to add unnecessary confusion and I don't beleive you wil need counters unless I'm missing something the 4.5 min timers is a good idea however. So am I correct in that you have three pressure sensors? each set at a different value or is it one sensor with a pressure return reading via analog of ascii?

Click to expand...

I have a water level switch. This is I:0/0.
Then I have a pressure transducer with an Analogue output feeding into a panel meter. The panel meter has relay outputs, so I:0/2 is low low pressure and I:0/3 is pressure achieved. I haven't changed the descriptions yet but they should read this. I also may have to look at the usage of the xic and xio bit from these.

I am using the counters for the pump selection. As stated already, I don't mind changing any of this as per your instructions

Conor