Hi Guys,
Been "offline" for almost 2 weeks - the organ grinder went to tea and a semi trained monkey who was left to mind the shop (read that as our local telecoms provider) pulled some wires out through sheer boredom or whatever... The result was no ADSL and a good few "mildly persuasive calls" to them to get them to check the exchange DSLAM ports and links... After numerous "the problem is on your modem" type remarks from the various "support" staff over there....well enough said...here's hoping some asshole doesn't go foraging for copper amongst my connections for a while....
A short post again... I skimmed through the previous posts and have but a few comments...
PLC - Hardware is reliable, O/S software is stable, timing, instructions and power consumption is well documented and of an industrial nature - Power consumption of this unit, driving 6 or so 40A contactor coils, is in the region of 10 to 15W - Idle draw is around 6 to 8w, a small price to pay for a reliable piece of kit. (that amounts to about 250ma on a 24Vdc battery bank, less efficiencies of course)
As to reliability and maintenance, while I love the simple liister/oids, these units would outlast a lister by a factor of 10000's at the very least - Granted, they are sensitive to power spikes a la lightning and major ESD, but in their defence, they are rugged little creatures that take little to no maintenance once set up. Like the lister, feed it clean energy, it will last longer...Way longer than the lister...
Bruce, I programmed this thing in Ladder, from start to finish, the display is an industrial HMI (human-machine interface)... The HMI has its own little bit of software to program it and get it talking to the PLC. the HMI is a touch sensitive screen, semi ruggedized for industrial app and quite simple to set up. Mostly menu driven, this old one still needs XP to run the programming software. The HMI links to the PLC via serial port, reading and interrogating the PLC register values for display, able to manipulate the registers for control..
Right, sir Glort, more of a description as to what this box of trix can do...especially since you got me thinking about it in the first place...
There are but 3 things that this toy now monitors - Battery voltage, Time, Available Light... Its amazing what can be done with these three little simple things, let's do a "for instance" in real world things to get the idea across, forgive me if I have done this earlier in the thread and I repeat myself...
Picture the scene: A lovely little garden path with cute decorative lights to pretty it up for the ladies...
Now the technical bit: The lights must only come on if there is enough "free power" reserve in the batteries, after 5pm for a couple of hours and only when it is dark..... So you set the power availability via a voltage choice - slightly above to slightly below the float value for your battery bank, set the timer for start at 17h00, set duration for 120min, and finally enable it for low light only... Walk away and it does its thing.....
Right, a guest has arrived...I will carry on with this saga a bit later....
<Back Again>
The saga continues...So much for it being a "short" post.... If my BS and rambling irritates, you, the reader....Ade....Kick me off the site!!
Now onto some more of the nuts, bolts and bit bashing that the PLC does... It does the roughly the same things for both charger inputs and power outlets from the battery/inverter.
The outputs have parameters that you can set up (5 outputs, each individually parameter'd)... This effectively allows for a pretty complex set of circumstances when run individually, or even capable of being series'd to allow multiple turn on/off times and controls to be set... Obviously, 2 outputs, series'd means that from a 5 output total device you will lose an individual output as it will be combined with another...
The mains battery charger output can be battery voltage controlled as well... A start voltage can be set, as well as a cutoff voltage for when charging must stop... This is particularly handy when a load is imposed on the batteries that cannot be unloaded when there is a lack of sunlight or wind... A typical example is my scary candy floss machine (fuge), that once started, is a PITA to stop halfway through a batch of processing, the mains charger kicks in and holds the batteries at just above a critical damage level until I am good and ready to turn off the peripheral devices and put everything to sleep. Of course, it is a good idea to have the auto switch-in that bring in the automatic loads(pretty lights etc) set at a cut-in battery voltage that is somewhat above the cut-out voltage for the charging... I wouldn't do to run this box of tricks as a gloried UPS now, or would it??? ...!...
All switched loads/charging parameters have a couple of individual "time factors" associated with them (even the daylight sensor)... This allows for the surface charge/drain on the plates to be catered for. For instance, if there is not a cutoff period associated, the contactors cycle when the charge voltage is a fairly narrow one, the charger or load drives or drains the batteries into the cutoff range, the contactor opens and the + or - load unloads... The cells then "spring" up or down in voltage slightly, causing the voltage monitoring to see the demand, the contactor closes, the voltage goes out of the required range and the cycling starts again... Add a custom shutdown/startup timer to precede or follow the band and it, at the very least, gives a minimum presettable on or off time for the circuit in question. Do a bit of cute watching and examination (read that as a smoke break and a pint) in front of the box, extend the timers as needed, and the charger, for instance, with a bit of shutdown delay, puts enough juice into the batteries to allow the circuit to shut down and not cycle on and off too much as it approaches target voltage (hysteresis looping 101).... but again I ramble....
As for the daylight sensor.... Well, a simple answer/example is: What if the sensor is placed in a walkway? Only a preset amount of time in shadow or light will allow it to start switching things, a typical use for this could be 10minutes after sunset, start doing something... Or an hour after sunrise, get things moving...
Now, why go to all this trouble and to-do for a silly little 1Kw wind/solar setup... Hmm... good question.... Honest answer... To see if it could be done!! And....Ultimately... to hook this silly little system into my 5kw household system so that I can get a bit of night time wind to charge the works... As well as rerouting a few "luxury" type appliance circuits from the DB board so that I don't have to have the proverbial cadenza when residents try and run dishwasher+ironing press+2xmicrowaves+aircon(and dont forget the clothes dryer and hair dryer at the same time) off the solar simultaneously... The box also has current measuring capabilities which I can easily implement (all written in and tested, just add current sensor) and then I can let it be the "bad guy" and turn off the loads until more power becomes available... Who me? Naaah.... Couldn't be.... I would never put a facility like that into play.... But come to think of it, isn't that a great idea...Lets keep it like this and see how it works out....
To put it in a nutshell, if that's at all possible, each connector to the outside world has individual settings for:
Start voltage + Start up delay timer
Stop Voltage + Shut off delay timer
Day Sense + Start delay timer
Night sense + Stop delay timer
RTC turn on + Duration on
Automatic one button timer (press button and the corresponding output is active for its own presettable time)
Forced on mode (Manual on, controlled by PLC and will only turn off when batteries go below critical level)
Forced off mode (All automatic control disabled, only forced on is available)
Overcurrent monitoring on the global output and shutoff in the event of limit being reached
Selections to allow Light monitoring or to ignore
Selection to allow Dark monitoring or to ignore
Selection to incorporate time monitoring or to ignore
Add to that a global time monitoring control and a global light monitoring control alongside a "panic button" to kill all outputs immediately as well....... I think I have most bases covered... Oh, Bob, if it does give sh!t...easy....Its' all plugged in with M/F kettle connectors, unplug the mess, plug the connectors together and climb on the light switches to try and run it manually!
Keep it switching....
Cheers...
Ed...
P.S....due to about 30 interruptions whilst trying to post this, the author makes apologies for possible repetitions, typo's and garbled trains of thought and comment....