Pumping relay setup

There will be one (or a few) right ways to do this, and a great many wrong ways. I forget the NO/NC/time configurations of various 8-pin or 11-pin relays and timers, and the function diagrams associated with each. Some manufacturer data would be helpful. Rather than model numbers, which everyone will have to look up, it would be better to provide the switching sequence and contact pin-out of the various components.

I would be tempted to use a low budget PLR system and do it all in the programming.

Teco PLR's are simple to use and program plus you can get the software free online before you buy the unit just so you can see if its what you can work with.

Here is where I get mine from. http://bb-elec.com/?gclid=CJ7S7_2Ht48CFRFSagod2hagcw The basic bottom end no frills unit is only $75 and still gives you 8 inputs and 4 relay outputs to work with.

pls. does ur low and high thesame as in high and low levels? If am corect, u will need level controls in addition to ur relays and timers. the contactors should be elrectrically inter locked for the two mixer pumps.

Dickson. Abuja, Nigeria.

I am using two NC closed floats to signal the relays.

This is the timer relay.

This is the Omron relay.

After seeing the relay diagrams, I went back to the original post. I couldn't fully figure out the rationale. Which float switch is lower, 1 or 2? Do the pumps feed into or out of the tank, or one of each?

Float 1 is in the mix tank. When the mix tank gets empty the float contacts close. That starts the feeder and the mixer. When the tank gets full the float contacts open, stopping the feeder and starting the mixer timer relay timeout for 20 minutes. When float 2 which is in the Delivery tank gets low the contacts close and the transfer pump brings fluid from the mix tank until the float goes high on a full tank and the contacts open. the transfer pump may not run while the mix tank is filling or mixing.

What are the coil voltages? This should be very simple wiring depending on coil voltages.

The coil voltages are 120 volt as are the pump, mixer and feeder.

Thanks! The picture clarifies things quite a bit.

Most of the "tetherball" float switches I've seen tend to switch at about the 3:00 position of their swing, and thus are not capable of large differentials. As a result, it usually takes two of them for each pump, one for low level (start pump) and one for high (stop pump), plus a latching relay.

There are at least three possible ways around this. 1) If such exists, a bi-stable ball that closes around 5:00 and opens around 1:00. Or 2) a pump of consistent displacement that can be started and timed, thereby eliminating the upper float switch. Or 3) Some kind of switch with a large differential, such as a diaphragm (air pressure) or ultrasonic switch.

Depending on just what kind of pumps you have, and how fast/slow the fluid might be used from the second tank, there are several combinations of options, each of which needs a compatible set of controls.

Tcmtech's earlier PLR (programmable logic relay) option may be configurable to match a number of such options, so it deserves a close look. I will now go back and give it a GA. (A PLR can be considered as a mini-PLC with just a few I/O and programmable timers. They come in handy DIN-rail-mount versions.)

Designing relay ladder logic control circuits is an enjoyable mental exercise. The current widespread use of PLC's seems to have resulted in a general decline in the ability to design this type of circuit.

Posted comments suggest that to design a circuit to meet Mr. Sandman's needs would be basic stuff, requiring almost no thought, but no sample circuit design has yet been proffered to illustrate that supposed simplicity.

Designing the required circuit exercised my mind for a couple of hours. I guess I wanted to see if I could still do it. Almost certainly there are other circuit strategies that would accomplish the same thing, but if this works Sandman 51, you are welcome to it.

PUMP CONTROL

- the ladder diagram assumes that the two float switches function as described- ie: one float per tank - each float device having a single set of contacts - closed when level low, open when level high.

- numbers on diagram correspond to relay and timer terminal markings.

Operation:

- At low level, Float 1 contacts close, energizing R1 (2,10), which starts Pump 1 through closing of R1 NO (6,7) contacts.

- R1 NC (6,5) contacts open, de-energizing Timer coil (timer control switch contacts 5,6 (not shown) jumpered together.

- Second R1 NO (2,3) contacts close, starting mixing pump and energizing R2 (2,10)

- Tank fills, Float 1 contacts open, de-energizing R1 (2,10) which stops Pump 1 and energizes Timer coil through R1 NC contacts, starting timing cycle.

- Although R1 (2,3) contacts now open, R2 coil (2,10) remains energized and Mix Pump continues to run through closed R2 contacts (6,7) and closed Timer contacts (2,4).

- Timer times out, opens T contacts (1,4), shuts off Mix Pump and de-energizes R2 coil, opening R2 contacts.

- NC R2 and R1 contacts in series with Float Pump 2 contacts prevents Pump 2 from starting when Mixing Pump is running.

PS: not sure if diagram sent - notify if not

To Sandman 51: I can design a relay logic circuit, but I'm not a computer guy and how to send the circuit diagram to this space has baffled me. Contact me at

canadianslidewinder@hotmail.com and I will e-mail the attached circuit diagram to you and you can post it if you wish.

Your posting has been well discoursed with tremendious inputs from the very good colleagues u will always want to meet on this website.

What I want you to understand is to choose the item that will acheave you popouse. Runing a factory is all about money and minimizing Man Hour loses. picking a programable system is a very eazy thing to do but you will be compleatly enslaved to it in case of it becoming faulty. You will either waite for a repair or a replacement, considering ur location, that will take days and making nonsence of ur projections.

While appretiating all the inputs, I still want to remind u, ur having a very small system to contend with. My candid advice is for u to consider durability, maintenance and repair when selecting an item. Use ur relays, timer and level controls to solve ur problem, in the event of any fault, ur solution will be by the conner shops.

I will send pictures of level control u can sellect from that will solve ur problem. if ur still in need of the cct drawing pls. indicate ur intrest.

Dickson, Abuja Nigeria.

I am interested in the pictures of the level control if you could provide them. Thanks

Check your CR4 email.