12V DC Motor Controls

[jeffc0987]

I am not an electrical engineer, nor do I know much about motor controls, and I was hoping to get pointed in the right direction for creating a custom programmable timer to drive a 12V motor.

My company manufactures solar powered pumps which we would like to run intermittently every 30 seconds, 1 minute, and 3 minutes. During each cycle, we want to allow control over how long the pump runs for. Basically we would need an on/off switch, 3 position switch for cycle time, analog input for run duration, and possibly run/fault lights.

I have seen similar timers designed to operate 12V appliances but many are limited to switching 8 times a day. Some of our requirements are:
1. Operate outdoors in a NEMA 3R rainproof box
2. Potted for moisture/shock issues
3. 12V +/- 10% input and output, 15A max
4. 3 cycle times; 2880, 1440, and 480 cycles per day.
5. Quick connects for input/output
6. Voltage sensing would be optional, so that when the batteries are low on charge we could reduce the run duration.
7. Run/Fault lights would be preferred, but we could go without them.

If anyone knows of a manufacturer who would be willing to work on something like this, or if something like this exists, I would greatly appreciate any information. Thanks

 

[crumblebear]

I cant help on the manufacturer pump but what your after is a very simple design and if i was you id have someone draw up the schematics and pcb artwork ( there are lots of places that will do this for you) Then have the pcbs made and finish the wiring and installation in case etc in house. this sort of thing tends to attract quite a large mark up if you purchase it as a finished component!

 

[Skogsgurra]

This would be such a little piece of cake for one of the forum members in San José that I do not hesitate to break site rules to mention him. Right, Smoked?

Pls note, I haven't broken the rules yet.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[itsmoked]

LOL Skogs.
True.

jeffc0987; Sounds like an ideal microcontroller application. Once you've stepped up to a microcontroller there are a lot of additional things you can do in that application for not much more cost. For instance you could add a display that tallies cycles, describes the modes, shows the battery state, perhaps soft-starts the pump, runs the cycles on a daily profile or the calender, monitors the temperature, and describes errors, to name a very few possibilities. With a little more additional cost you can take on all the solar charging tasks. You can also enable communications links to provide remote control and error notification. Lots of possibilities.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jeffc0987]

Thanks,

I have found a few places today that seem to be very confident that they can accomplish what I am asking for. I was definitely looking for a micro controller, and was in the process of getting something custom made by our motor manufacturer, however it wasn't EXACTLY what we were looking for. All of the additional options would be great, but this is also designed to be something extremely simple to set up out in the field and having too much is confusing/intimidating for the people who are setting them up.

Eventually I hope to cut my teeth on some micro controllers along with the work I have done with PLCs. I see a lot of DIY projects involving micro controllers that seem pretty interesting to me.

Again, thanks for all the responses today.

 

[itsmoked]

As they say skogs, "You can lead a horse to water"...

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Siemens makes a little "Smart Relay" called the LOGO! (the exclamation point is part of the official name) that runs on 12VDC. Lot's of competitors make them (including my employer), but the Siemens version comes in an "extended environmental" version that has a higher temperature ratings (I think 70°C) and conformal coated boards for resistance to condensation. It was specifically designed to be used on portable machinery with 12VDC battery supplied power systems. It has the ability to accept programming for all kinds of timer functions, real time clock functions and can have analog inputs. It also has a very low cost and simple HMI (Human Machine Interface) either built-in to the front or there is a remote version if you want users to have access on the enclosure door. You can program simple instructions in plain text, multiple languages and can go simple graphics. I know of people using them on battery powered systems to monitor the battery voltage (it has a 0-10VDC input option, so you have to drop it a bit and scale it in programming). The advantage over a "green board" approach is that it is a COTS (Commercial Off The Shelf) product that can be easily replaced by users if damaged and you can store your programming on a little removable memory module. So if something happens, they buy a new one, plug in the memory module, cycle power and it's back to being what you provided. same is true if you discover later that you need to tweak the programming: just send out a memory module to the field instead of a whole new unit.

If you need someone to program it, see above...

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[jeffc0987]

But you can't make him drink; no need for the facepalm though.

I did see the flaminsystems.com, and I looked into it. I'm sure that a custom design could be made, however during my searches I happened upon a company that does extensive custom work, and already has an OTS model with ~95% of the features I was requesting. The only modification they would need to make would be to add a 3 position switch allowing for different cycle durations. I am actually a bit surprised that I couldn't find a percentage timer manufacturer that has one OTS with adjustable cycle times.

 

[itsmoked]

OK. Thanks for that info. Sometimes we rack our brains because a seeker just seems to not bother clicking an in-their-face link that can provide a solution. Sounds like you've done some good sleuthing and have found a able solution. As for your 'surprise' most of us seek "simple solutions" for little problems and come up 'surprised' too.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[blacksea]

One of key desadvantages of suggested above "smart relay" is inability to control such DC motor with 15A current. Than single axis motion controller with build-in power amplifier can be better way - for example from Elmo, Copley, AMC.

 

[ScottyUK]

I can pretty much guarantee that a smart relay plus a solid state relay, large mechanical relay or a small contactor will all result in a lower installed cost than anything involving a motion controller.