electronic load controller

[crisp]

looking for device or circuitry to control my generator, which is connected to normal household variable loads, at approx 3/4 max generator load using dump loads such as water heater and night storage heaters. Hydro load controllers monitor frequency to control  dump loads i need to monitor current via a current transformer.  Any thoughts please

[eabadger]

Not sure I 100% understand what you want to do, monitor current used and then dump accordingly?
You can get some very good voltage and current sensing relays, I use them off grid to divert loads and keep generator loaded whenever possible at 90% when on, depending on generator you could monitor AVR field voltage which will increase as load increases.

Is this the sort of thing you were after?

steve

[crisp]

sorry if not very clear , not so clear to me when i reread it .What I've got is a generator running on a light load most of the time ,what i want to do is load the generator with useful dump loads eg.water heater,  night storage  heaters that will drop in and out depending on the base load, to maintain more or less 3/4 load on the generator.the generator is avr controlled. hope that is clearer

[eabadger]

Much clearer, we are off grid and do what you are planning, when generator is running I try and load as near to maximum as possible, you could measure the output current, but do voltage tests on avr output would be doing the same job, avr voltage will increase and decrease to make sure output voltage is spot on, depending on generator.
I have used Elko relays to monitor voltage on both generator supply and wind turbine, when voltage X is reached relays bring in contactors which divert turbine to dump load from batteries, also when load is low on generator immersion heaters are put online, so wife has washing machine on, after heat cycle has finished immersions come on and oil filled radiators, but I do latter manually, as it suits me better, I have a second relay drop out immersion when voltage on avr exceeds 36v which is maximum on my generator at 5.6kva, it has a timer contact, to hold off dump for at least 3 mins, just to stop constant cycling on and off.
On the wind turbine I am hoping to use a air source heat pump as a dump load instead of conventional loads, as  want to be greedy with the COP figures, if I am dumping heat, might as well get 3x the amount, needs more work for last bit, almost bought a Trianco 1kw input airsource unit, but was not what it was purported to be.

Are you to be or are totally off grid? Mine was initially through necessity as no power to site, we have now been offered mains at a cost of €3,500 but are not jumping at deal, which we may live to regret, want to live as cheaply as possible without monthly bills, but don’t we all?

steve

[crisp]

   I will try and check the voltage of the AVR seems like one way to go if, the voltage could be fed to a pic and to dump loads via triacs if i could work out the circuitry.
  I am not off grid but looking to put together a chp system , using a gardner 4 cylinder engine,running on veg oil coupled to  a 14 kva alternator . Here in France your standing charge for electricity depends on the strength of supply you want , you can have a supply as little as 5 amps , to 3phase with 25 amps on each phase , the more you have the more the standing charge , so my idea is to cut down the supply from EDF and top up using the generator plus supplying hot water for heating  ,probably not economic but a interesting project , and a excuse to run a lovely engine    john

[stephendv]

I built something like this (well with the opposite intention) with an arduino, a clip on current sensor and a 10A solid state relay, both connected directly to the Arduino, no circuitry required.  Basically it would auto-start the generator every 24 hours, which would power my well pump, since water levels are variable, it would then monitor the current if it dropped below 7A it meant that the well ran dry and the arduino would turn off the gen and wait another 24 hours.
Also added SMS capabilities so that it would send me txts when the gen came on and off, and I could override the timer with SMS commands.

Regarding the setup in france, could this be a good reason to run with a battery based inverter fed by the grid?  E.g. if you had a 5A supply, that's a constant 1.1kW that could go towards charging a battery bank.  Then use a 3kW or even 5kW inverter to feed your loads.  With a 5A supply you could store 27kWh/day.  And since you have a constant energy source with the grid you can buy a much smaller battery bank than is needed by a truly off-grid system.

[crisp]

just looked up what a arduino is , looks really useful for experimenting and learning with, looks like electronics mecano.   john

[eabadger]

where in france are you? we are in 53, making the move perm next month, 4 small children in tow.
up until now all off grid stuff was to save paying for a new supply line €3500 plus then having french sparky do the work.
but we may now be buying our neighbors house which has power, but we want to save money, so solar wind and oil generators.
steve

[billi]

Regarding the setup in france, could this be a good reason to run with a battery based inverter fed by the grid?  E.g. if you had a 5A supply, that's a constant 1.1kW that could go towards charging a battery bank.  Then use a 3kW or even 5kW inverter to feed your loads.  With a 5A supply you could store 27kWh/day.  And since you have a constant energy source with the grid you can buy a much smaller battery bank than is needed by a truly off-grid system.

 

http://www.youtube.com/watch?v=q3svW8PM_jc

Billi

[crisp]

  we are in central Brittany area 56 . good luck with your move , or as the french say bon courage . Billi i don't understand what kc and the sunshine band has to do with anything, including music , presume you put the wrong youtube link   .  john

[stephendv]

Hehehe, Billi likes the idea of a semi-off-grid battery based system, yeah baby, that's the way he likes it 

[billi]

  

Billi likes the idea of a semi-off-grid battery based system

   and if one runs the generator  controlling/  using it at 3/4 of its power is easy

Yes  ,   what are  the costs  of a 5 A connection  compared to a higher Ampere one ?

Or  other idea is to grid tie the generator and feed into the grid , or is this not supported in France ?

Billi
 

[eabadger]

hi crisp, not that far away then, what price is fioule/red diesel now? have you got any solar pv?
got about 500w at the mo, but another 1kw later today is being picked up.
have you got a deal at the loacal cafe for oil? as svo in shops is more than red, think we paid 68c ltr at christmas.
would love to collect used oil, but dont know how to start, begging in a different langauge.
seems a mighty big engine to run all the time, is it to be on all the time?
we have a twin diesel and try and run as little as possible, but still have plenty of power, as you say the tariff is based on max load, our 5.6kva generator is rated higher than our neighbors edf supply!
i have got some smaller generators to just run light loads, can never have too many!
i know you can grid tie in france as my mate is a french sparky in 44, but dont think the deals are as good as in the uk by a long way, or am i way off?
just heard that our wind turbine doesnt need planning as is just less than 11mtrs, hope that is true, as we hear diferent thing at different times.

you been out there long?

steve

[crisp]

did some checking on french standing charges for electric the paper I've got is a few years out of date , but gives you some idea   3kva supply 1,99e   a month  up to 36kva at 69,37 euro a month  in graduated steps, we have a 12 kva supply 3 phase which on the present bill was 14,76 e  per month.solar panels seem to be getting popular over here at the moment , a local agricultural coop warehouse is covered , must be 60m x 10m , and a local sports hall are just being fitted covering one side of the roof i would think that feed in tarifs would be good if you ever sort it with french bureaucracy . not really interested as not planning to stay here longterm.

[Dyslexicbloke]

Have you considdered a little programmable relay, baby PLC.
I use a Siemens LOGO! .... it is 12-24V DC supply and comes with 8 inputs, two of which are analouge and two will count fast pulses.
I picked up mine on ebay for £70 with an aditional IO module giving me 8 output relays and 12 inputs.

RE sensing ... You could use a small hall effect current sensor, or a VT which is like a CT but giving a DC voltage proportional to the current rather than another current. VT's ar usuly built with hall effect sensors but somone else has done the amp calibration for you.

Your AVR field output voltage will offer a good indication of generator load BUT it will be high voltage and would need either a high impedance amp or some other form of isolation to be connected to a control circuit safely.
You might also find that some loads mess with the waveform and could give inaccurate readings.

One final point .... If you want to keep it super simple use a VT and a bar graph chip ... 8 or 10 cascaded outputs at regular intavals and only a resistive devider between that and the VT, simply scale it as you want to and if you need an offset a single opamp as a buffer will do that for you.

Hope tis gives you something to research and play with.

Al