power supply for a hydrogen fuel cell basically

Discussion in 'The Projects Forum' started by chaz0144, Mar 18, 2016.

  1. chaz0144

    Thread Starter New Member

    Mar 18, 2016
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    I need help sizing a capacitor for a 1600v. 100 amp full wave bridge rectifier my input will be 120v ac output 120v dc but will vary between 120 to 0 and my amperage will vary between 0 and 100
     
  2. Sensacell

    Well-Known Member

    Jun 19, 2012
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    Huh?

    Where does 1600 Volts come from?
    Please post a schematic or block diagram of your system.
     
  3. chaz0144

    Thread Starter New Member

    Mar 18, 2016
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    That's just max voltage and amperage for rectifier I'd have to draw a schematic we will be running test on a more elaborate system I just need a good power supply to start from then once I get results most likely I think I will need to Automatically Adjustable Voltage As Per Amperage Because Water Supply Will Change
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Please don't plug it into the wall outlet.
     
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  5. chaz0144

    Thread Starter New Member

    Mar 18, 2016
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    I just need the capacitor size that will be able to handle 120v to 0 and 0 to 100 a I have a adjustable ac supply 120v going into a bridge rectifier going to be most likely 36 dc fuel cell will be completely enclosed in a insulated container with proficient protection
     
  6. Marcus2012

    Member

    Feb 22, 2015
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    If you're purely in the experimental stage and you need 36VDC as your supply I would be tempted to use three cheap 12V lead acid batteries to get your 36VDC for you electrolytic cell. You can draw large currents from them and this will allow you to finish the cell design before committing to a potentially expensive power supply. Turning down mains voltage here in the UK would give us more power than a 120V supply and you'd still probably be limited to about 30A at 36V. I'm guessing your not sure what the current draw will be yet, is that right?
     
  7. chaz0144

    Thread Starter New Member

    Mar 18, 2016
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    No already did this my amp draw is from 5 amps to 9 amps at 36.7volts and water at a ph of 7.5 but my water conditions will change and my cell will be bigger and I will need my amps to stay the same so I can have the same out come this isn't for hydrogen production
     
  8. chaz0144

    Thread Starter New Member

    Mar 18, 2016
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    so my wattage because of water conditions will change so is there a capacitor for bridge rectifier that will compensate for the changes because I'm sure I will have to change my voltage to keep amperage the same because I need the same out come but don't know what level it will be until test have been done
     
  9. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Okay, here is the deal.
    It is against the rules here to do circuits that are not isolated from the mains power.
    Your power requirements seem unrealistic. 12.000 watts is as much as is supplied to many houses.
    You can make me a believer with a photo of your transformer. :rolleyes:
     
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  10. Marcus2012

    Member

    Feb 22, 2015
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    Ok so you're scaling up your design? I'm a little confused as to what supply you want for your scaled up design. Using directly rectified mains is dangerous as Ronv mentioned because it is not isolated. Your maximum power available on your load side cannot exceed the power available from your mains input. Here in the UK we can only realistically draw 3.12kW (240V*13A) so this is the MOST power we can have regardless of what we transform the voltage to, the current available will be indirectly proportionate to your voltage manipulation. That is in an ideal world with 100% efficiency and that world doesn't exist outside our minds, we always have losses.
     
  11. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    :confused: You said "this isn't for hydrogen production".
    Your thread title says you want a power supply for a hydrogen fuel cell, but why would you supply electrical power to a fuel cell, which is already a power supply for generating electricity.
     
  12. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Sounds like the TS is trying to get around the HHO/Browns gas thing.
     
  13. chaz0144

    Thread Starter New Member

    Mar 18, 2016
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    In the US we have at our home 240v. At 200a.but I'm doing this at work where I have 480v.200a. If need don't think I'll required that though I won't know what my true wattage will be till its built but I can say it's for breaking bonds in the impurities in the water
     
  14. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Okay I will play. I love these vague I don't know what I am doing or talking about but I need high power to do it threads anyways. :D

    120 VAC rectified and ran through a capacitor will give you around 160 VDC after losses and ripple are factored in.
    Now given your 100 amp capacity rectifier I would assume it has a pretty high peak current rating so rectifying 120 VAC @ 100 amps RMS likely won't kill it due to excessively high peaks.

    Anyway for a 100 amps @ 160 VDC I would recommend a 40,000 - 60,000 uF capacitor bank but being electrolysis is not that fussy about ripple you could cut that down to 10K or less.

    As for voltage and current control either you will have to go to a solid-state phase angle controlled regulator system or a huge assed variac transformer or more practically an old fashioned magnetic amplifier regulator system like what was used in arc welder power supply before modern solid state control came into being or run a large bank of motor run type AC capacitors in series with your live line to limit the current by simple capacitive impedance. That would be the simplest and cheapest method to go with.

    That ought to keep you busy reading about wht I have underlined online for a while.

    He probably has the same style I have (grey tank on a nearby pole or big green box in the yard) that isolates him from his main utilities 7200 volt system.

    Despite how some will squeal there is nothing illegal about running a high current load off of one leg of your homes 120/240 power system if it was built to work as a true 200 amp system.

    The general rule of thumb for system loading would be not to go much over 80% of your system capacity for continuous duty application which in your case would give you 160 amps on a single 120 volt leg provided you used properly sized fuses or circuit breakers.

    Personally, if I was you I would be looking at finding a big old constant voltage ( MIG/wire feed type) type welding power supply.
     
    Last edited: Mar 19, 2016
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  15. Marcus2012

    Member

    Feb 22, 2015
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    Yes you may be able to draw large currents from your mains but is your ring main rated to handle that current? Probably not and that's probably why it has something like a 30A breaker on it. It prevents fires. Doing it at work makes sense but I'm guess that's 3 phase supply?

    EDIT, Isn't this supposed to produce more energy than it consumes? or did I miss something?
     
  16. tcmtech

    Well-Known Member

    Nov 4, 2013
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    We don't use a ring main system here in the US. All of our residential systems ar based on three wire, with earth ground, split single phase systems (120 - 0 - 120 with 240 across the two 120 ends) which will allow for drawing a substantial amount of current on a single line if you need to.

    Around here a standard 200 amp home service would have 4/0 size cable supplying the two 120 VAC sides of the split 240 VAC supply and a 2/0 - 4/0 center for the common/earth ground line as well all designed and rated to handle at least 80% of rated capacity continuous duty.
     
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  17. Marcus2012

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    Feb 22, 2015
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    Ahhh I did not know this thank you :). I was under the impression it was a two line 120V and neutral but that cable would handle that even on a spur. Do you have separate outlets for utilities? Here I think the general thinking is that it's cheaper to distribute the load over a ring main so they can use thinner cable. In all honestly though it sounds like your system might actually be safer.
     
    Last edited: Mar 19, 2016
  18. tcmtech

    Well-Known Member

    Nov 4, 2013
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    I would say both systems have their advantages and drawbacks.

    Over here the standard circuit for 120 volt power is either 15 or 20 amps although there are sockets and breakers available to put in single 120 volt 30 amp circuits as well.

    For power usage above that the standard is to go to a double breaker or fused 240 volt feed which as with the 120 volt single lines start at 15 amps going up to 20, 30, 40, 50, 60 and so on from there with specific socket configurations for each.

    The largest of the common single circuit sizes are 100 amp 240 volt but sockets for that amp capacity are rather spendy so most people wire the devices directly or cheat and put the 60 amp ones on the 100 amp circuits. About the only times individual circuits of that capacity are used is in a shop or garage where large high powered equipment like welders, plasma cutters or large motors or heating units are used.

    In a residential environment it's rare to see anything more than a 60 amp circuit used and that would be for a large electric stove, central air conditioning system or on demand water heater system. Anything bigger than that like an electric central heating system or high capacity on demand water heating system would use two to four 50 or 60 amp feeds opposed to using a single 120, 150 or 200 amp single breaker set.

    That said the standard now for residential is a 200 amp minimum service but on most newer farms and large homes 300 - 600 amp single phase services are becoming common.

    So ya over here we build our systems with the capacity to allow for us to suck a huge amount of power if we need too! :D
     
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  19. hp1729

    Well-Known Member

    Nov 23, 2015
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    I haven't read the other posts yet, but general rule is 1,000 microfarads per amp assuming full wave rectification at 60 Hz. So 100,000 microfarads? This doesn't have to be one capacitor. I suspect better calculations can be made.
     
  20. tcmtech

    Well-Known Member

    Nov 4, 2013
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    That's sort of true but mostly for low voltage power supplies where a less than half a volt ripple at 120 Hz accounts for more than 5 - 10% of the working voltage.

    At 160 volts that same .5 volt ripple would be tiny and the 100,000 uF 200 volt capacitor bank to make it so a rather spendy unit to build thus going by percentage of ripple to system nominal working voltage allows for a much lower capacitance to be used.

    By my estimates a 10,000 uF bank would be more than sufficient for an unregulated 100 amp capable electrolysis system like the OP wants to build.
     
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