Question for Spasse, and others (EE)

[Ltspd]

I have a GE Fanuc Series one PLC that I control the lights on my tank with. I have 21 120vac outputs and 7 24vdc inputs. I have the programmable keypad which I use to set my times for the lights. I will be reprogramming the PLC for the new tank and there are several things I would like to do with the PLC. I do not program I have several friends that program with directsoft (I think thats the software) that will do it for me.
I want to speed control (4) fans off of 1 temp probe. I know the fans (120vac) can be speed controled becasue I have done so with a simple light dimmer. I do get typical dimming hum from the cheap dimmer. What or how can I acomplish this? I can switch to DC fans for easier speed control if need be.
I would also like to run a solenoid to a ph probe for a calc reactor. I want the set the limit for the reactor output to come on and off when the ph drops. I am very unfamilar with reactors so far, I am constructing one currently. I have the reg but have not gotten the needle valve or solenoid as of yet. These are easy items to come by. Can the PLC handle the switch? based upon the signal of the ph probe. I assume that the probe is 4-20mA?
If Spasse or anyone can help me with the cards or PLC devices I need to aquire for this control I would greatly appreciate it.
The PLC is the one on the left hand of the power board.

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Paul C
Things should be made as simple as possible, but not any simpler.
Einstein

[This message has been edited by Ltspd (edited 03-03-2001).]

[SPASSE]

Ltspd,

I will post to this latter, as this will require some research on my part.

And a higher number of brain cells than I currently have at my command.

Regards,

Scott

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The definition of an expert is a washed-up drip under pressure.
You can see my reeftank at http://www.homestead.com/spasse/

[Rin]

Ltspd,

I'm not Spasse or an EE (I'm a Chem Eng), but I do have 5 yrs experience with installing/programming Modicon PLCs. The basics for all PLCs is the same.

I just visited the GE Fanuc website www.gefanuc.com

There isn't a whole lot of information on your model of PLC. I guess it was built around 1994 and it's not supported much any more. They do have some information and numbers to call for manuals and support.

The program you will need to program your PLC is called Logicmaster. There may be third-party programs, too. It's just a matter of matching your model with the program. You'll also need an interface cable to between your PLC and personal computer. This can be built or purchased from GE if you don't already have one. They may even sell it with the Logicmaster program.

Controlling your fans off temperature will require that you install an Analog I/O card. These are not cheap ($1000 or more) and may not be available for your PLC. Looking at what little information there was on the Series One, it appears that GE sold it as a single until. Most PLCs are modular by nature and can be customized to any mix of I/O. Yours doesn't appear to be that robust. But I could be wrong. Do you have any Analog I/O channels on your PLC?

Lets assume that you can use Analog I/O. For the fans, you'll need a card with both Analog inputs and Outputs...most cards are either one or the other. If you can't get one that has both input and output, you'll have to get 2 cards. You would connect your temperature probe's 4-20 mA signal to the analog input. You then connect your fan to a 'speed controller' which will accept a 4-20 mA (or 1 - 5 VDC) signal from the analog output card. Your friend would program the PLC to control the fans (based on temperature input). If you want independent control of each fan, you will need 4 analog output channels (most analog cards have 4 - [img]/ubb/uhoh3.gif[/img] connected to 4 different speed controllers. Alternatively, you can use resistors and connect several output channels to the fans (in parallel) and have 'step' control. This is much cheaper than the speed controller option but will use up a lot of your digital output channels. The temperature probe will require calibration...I've spent many a late night doing this.

Your pH system is a little simpler. The 4 - 20 mA signal comes into the Analog input card. Your friend, again, programs the PLC to activate/deactivate the solenoid, which is connected directly to a digital output channel. Solenoid will also be connected to a valve on the calc reactor. You will need a valve specially designed for this operation. Again, you will have to calibrate your pH probe.

If you can't use an analog card, all is not lost. There are special relays that can recieve a 4-20 signal and activate/deactivate based on a manual setting on the relay itself. This takes some of the programming (and the fun) away from the PLC.

Your model of PLC also has an RS422 port. You can connect this to a PC and with special HMI (human-machine interface) software, you can monitor and control the setpoints of your system.

I hope to do something similar one day soon. I just don't have the $$$ right now.

In the end, you'll probably find out that it is cheaper and easier to get one of these ?Neptune? or ?Octopus? controllers sold specially for the aquarium trade. But it wouldn't be near as much fun, and using a PLC is much more versatile. PLCs are also not prone to the problems with using x10 modules.

HTH. I've glossed over a lot. Feel free to ask more questions.

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-Todd
'Looking into the cake is like looking into the future--until you've tasted it, what do you really know? By then, it's too late.' -Merlin Excalibur

[This message has been edited by Rin (edited 03-04-2001).]

[Ltspd]

Thanks for the help so far, I will require lots more [img]/ubb/lol.gif[/img]
First let me say I am mechanical and not electrical. I design the machines and tell the EE's what it needs to do. I ususally tell them I dont care how you do as long as I can plug it in and make the machine work I am happy.
OK, the GE fanuc I got is a old one, which is why I got it for the remarkably low price of free. My company and a lot of the guys I do business with also get salvaged machine parts so it came off of a old machine. Fortunatly I do have spare parts for it. I had the only card I am using blow on a surge and was able to replace it from scrap. I will be looking today for a I/O card to see if I may have one already. I went to www.automationdirect.com and from my limited knowledge was able to find some I/O's but them seem much higher than what I want to spend (200-300) and I didnt find a I/O together only input or output seaperate. I may not even be looking at the right things [img]/ubb/lol.gif[/img]
Ok, here are some more questions. I may be better off buying IC fans, but this takes ALL the fun out of it and I have to admit defeat. Can I use a house thermostat? or fan controller from HVAC end of the world? This accomplishes the task, still is high tech, and I got to create something. Another question, which I plan on raising as a seaperate post. Do you (reefers) that have IC fans notice them actually changing speed often. Or do they sort of hit say mid speed and stay there. I am curious if I just had a good dimmer (low hum) if I could manually vary the fan speed myself. I have (4) 115cfm 4" fans that I plan on putting in my hood. This raises another question, do I need that much? I will have (2)250w mh's, (1)175mh and (4)96w pc's over my soon to be 168g (60x24x27). Maybe all I need is 2?
As far as the ph control, it sounds as if I need a I/O card for that to happen to, guess I need to get busy finding one of these cards.
The PLC I have has a digital screen and key pad allowing me to set my times for each device. It is programed to count, and reads in military time. I have to set the 00 hours and 00 minutes to set everything up bases upon the programed address. I can view what each device is doing and also have a 00,00 output display telling me time. This was cool because this is much more accurate than my watch and I can check time everytime I passed [img]/ubb/lol.gif[/img]
The software and interface I have at my office and the friend that programs it also has. The plant he works at (I do business with) has quite a few Fanuc's running a lot of machines. These are being upgraded slowly.
Thanks for your guys help so far, as I said I will require more. [img]/ubb/smile.gif[/img]

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Paul C
Things should be made as simple as possible, but not any simpler.
Einstein

[Ltspd]

Is this what the I/O should look like? I thought it would be a card that plugged in the chassis. http://cgi.ebay.com/aw-cgi/eBayISAPI...item=565276869

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Paul C
Things should be made as simple as possible, but not any simpler.
Einstein

[golfish]

Paul,
I installed 2 fans in the hood of my 55 and I thought it was going to lift off the tank[img]/ubb/smile.gif[/img] plus the noise. I don't see any reason why you need more than 2 fans, I would install 1 fan on each end of the hood blowing into the hood.

Mark

[Rin]

I don't know if 4 fans is too much--they might be. What are your hood configurations? Is it completely enclosed or does it have any vents (other than the 4" holes for the fans) Are the lights to be mounted inside the hood or on top? How many cu. ft is the inside space? The key to determining your requirements is figuring out how much heat the lamps put out and balancing that with the amount of cooling the fans will provide. Another factor is evaporation. The fans will help increase evaporation in your tank. Evaporation will make up a lot of the cooling effect on the tank. Determining evaporation means you also have to determine the radiant heat output of the lamps, which is different from the thermal output of the lamps. Radiant heat can be estimated by covering the tank with glass and measuring the heat rise in the tank over time. You don't even need to have water in it. Sometime soon when I'm bored, I'll try slapping together a simple thermodynamics equation that might estimate cooling fan requirements. [img]/ubb/lol.gif[/img]

Back to the I/O card. No, the one on Ebay appears to be a generic analog card for an Open Control System (OCS). The model number is different, but I use similar cards where I work.

Your best bet is to call GE Fanuc tomorrow and get the exact model numbers of the cards that are compatible with your Series One. Companies, like GE, sometimes give out 'Specifier's Guides' which detail all of the model#s and capabilities of every component they make that are compatible with a particular control system--like the Series One. Most likely the catalog will cover every component they make for their Series one thru Series six. These catalogs are generally free. Act like you're representing your company and they'll be a little more helpful. [img]/ubb/wink.gif[/img]


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-Todd
'Looking into the cake is like looking into the future--until you've tasted it, what do you really know? By then, it's too late.' -Merlin Excalibur

[Rin]

On the question of an house HVAC thermostat, you could use one for on off control of the fans, but it wouldn't be able to do speed control. Like the ICs, it would take away from the fun of a PLC. [img]/ubb/biggrin.gif[/img]

That automation direct website was pretty cool. Their PLCs are very cheap and might be perfect for home use. I could put together my entire PLC for less than $1000 plus the cost of field instruments. I wonder if the PLCs come in other cool colors? [img]/ubb/lol.gif[/img]

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-Todd
'Looking into the cake is like looking into the future--until you've tasted it, what do you really know? By then, it's too late.' -Merlin Excalibur

[Ltspd]

Rin, The hood will be completly enclosed on all 4 sides except the fan openings. I will have 3 doors across the front and a hinged top, but they will closed 99.9% of the time. I will have (2)250 and (1)175 and (4)96w pcs' inside of this hood. I will have a spectral or similar reflector covering the whole top area, with maybe 1/2" air gap between the reflector and the hood top. Bulbs will be approx 7" from water level to center of the bulb. CFM of each fan is 102cfm @ 41dB full speed. These fans move some air, I will have grills on the outside as finger gaurds. I may have to cut some air slots in the back of the hood but dont really want to if at all possible. I want to keep the light in the tank. This is why I felt I might need 4 fans. Tank will be open topped and I know I will have a evap of a couple of gals per day, or a rainstorm inside the hood, [img]/ubb/lol.gif[/img]
I went by the office and dug through the junk. I have one more Fanuc chassis and 120vac input/output cards, the cpu etc. My PLC has (3) 120vac outputs and (1)24vdc input card along with the cpu. I did find a old LARGE ABB plc that had I/O cards, this thing was atleast 2ft square and 18" deep, it was HUGE. One top of all this I found several flowmeter, temp gage, solinoids, etc. Great having a junk pile to scrounge through.
I checked at the HD this morning in regards to thermostats, no luck. I know a friend at a HVAC place and may be able to get some sort of fan speed adjustment based on temp from them. I also posted about how much speed change the IC fans do and I may be able to get away with "dimming" the fans to a slower speed and accomplishing all I want when the bulbs are on. http://www.reefland.com/ubb/Forum14/HTML/000784.html
Or maybe (2) at full speed are sufficient, I would jsut like the capability of speed control based on temp, sounds cooler. [img]/ubb/lol.gif[/img]


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Paul C
Things should be made as simple as possible, but not any simpler.
Einstein

[Rin]

Paul,

I've done some very rough calulations about what causes the water to heat up so much.

It comes down to two things: thermal heat and radiant heat.

With thermal heat, the bulb heats the air and the air heats the water. Let's say the air inside the hood gets to a scorching 150°F. Losses from the hood (without a fan) occur through the sides and top and natural convection through the cracks. They also go into the water. I assumed the surface of the average MH bulb is hot enough to cook with--300 - 400°F. Accounting for losses through 1/2" thick wood and 23 sq ft of area--the remaining heat is transferred through convection to the water. The equations for convective heat transfer are complex but I took some shortcuts and came up with about 26 BTU/(hr-sq ft) or 312 BTU/hr for your tank. Since the system is closed very little evaporation will occur. After 12 hours the temp rise from 80 will be 3° (in a 168 gallon tank).

For radiant heat: Your total wattage is 1059. For simplicity I counted the PCs as the same radiant heat as the MH. I will also spread the radiant heat across the area of your water column. So the total effective wattage will come to half this value or 530 watts. More complex equations and your radiant heat output is 225 BTU/hr-sq ft. (congratulations, you've matched the sun in Florida.) With your tank you are putting in 2700 BTU/hr. Over 12 hours this comes to 32400 BTU!!!!!! or a temperature rise of 23°F. This, naturally, is very unrealistic. My model doesn't account for heat losses through the tank glass or sump area, which are significant at this level!

What this model does demonstrate is that thermal heat rise is insignificant when compared to radiant heat rise. The only way to stop radiant heat is to remove it from the water. This is done primarily through evaporation. We ensure good evaporation through good air flow. We can calculate air flow required but this is only important if we wish to make the hood cooler. As I have already shown, thermal energy is not important--so why bother?

What is important is that the relative humidity be low enough to cause evaporation to occur in the hood. So now we've effectively created a cooling pond. The heat of evaporation of water at 80°F is 300 BTU/lb. You can potentially evaporate 13 gallons of water. Still unrealistic and probably shows an error somewhere in my calculations. But I also don't account for heat losses through the glass, as I've already said.

So what does this mean? Probably that you will need those four fans to evacuate all those BTUs without seeing a temperature rise. I beleive that you are going to loose a lot more water than you think.

That was fun. [img]/ubb/biggrin.gif[/img] HTH

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-Todd
'Looking into the cake is like looking into the future--until you've tasted it, what do you really know? By then, it's too late.' -Merlin Excalibur

[Ltspd]

Todd, nice calcs. If you have formulars handy and can post please do.
Ok, with what you have said it leads me to initailly think that I will benifit from having the back of the hood partillay open and fiberglassed screened. This would ease the amount of space that the bulbs are contained in by allowing some natural airflow. Also it would allow the hot air to be forced out by the fans.
I visitied a friends tank yesterday. 360g show and 200g sump. He has a chiller but was running (2)400w Eye's and (4) 48" VHO's in a small box style hood that was suspended on top of the tank. He had (2) fans, 4" ones. The box wasnt hot to the touch with only 1 fan running. Now the chiller does nothing to cool the lights down. So, am I over estimating my needs? This may be one of the working experements I need to do. I will have all 4 fans in my hood. I will wire so that only 2 come on initially, probally at atleast a "dimmed" speed (or capable) and see what I have as far as heat. Of couse I will need to be around when doing this. If I need to I can run the other 2 fans. I will be circulating the water to the sump which will be located in my basment and will be much cooler there. The 2 things I dont want to do: 1) have to run a chiller. 2) set the house on fire.
I may also have to set up a good top off system in conjuction with my ro/di unit to overcome evaporation.
Thanks for all the help! This is fun.

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Paul C
Things should be made as simple as possible, but not any simpler.
Einstein