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Best way to test various 110vAC loads — Parallax Forums

Best way to test various 110vAC loads

akalatiakalati Posts: 31
edited 2010-11-18 11:24 in General Discussion
Any ideas on what's the best way to test a micro-based AC wall switch with various load ranges (20w thru 800w)? A brute force way of doing this is getting a bunch of lamps, all plugged into the same power strip, connected to the unit, and power each lamp on/off as required. But I thought that someone here may have experience with a more elegant / smarter way of doing this.

Thanks,
Andy

Comments

  • Peter KG6LSEPeter KG6LSE Posts: 1,383
    edited 2010-11-17 21:30
    use a Diode bridge and a PWM a big FET..and fuse :)

    If V = 100 lets say and we "draw" 10A we are Useing 1KW .

    now lets assume a FET has 0Ω on Resistance .
    and 1MΩ off . we can now plot a graph of duty Cycle a to "effective" Resistance based on its ON time.. for simple math sake lets say 50% duty = 500KΩ . and so on and so forth .


    and Mr OHMs law can kick in and volla digital load .


    now You will need to assign a curve factor . Prop or BS2 can handle this. cause IRL the 50% will not be 500KΩ . , so a a scaling factor is needed ...

    http://www.westmountainradio.com/content.php?page=cba
    this little toy may give you some Insight ..

    its for batts but the same idea applys
  • kwinnkwinn Posts: 8,697
    edited 2010-11-17 21:53
    Since you say "wall switch" I assume this could be used one or more incandescent bulbs. I would suggest several bulbs and switches in parallel to select the load. Least expensive solution I have found.
  • ercoerco Posts: 20,260
    edited 2010-11-18 01:03
    Of course lamps are purely a resistive load, much safer & easier to switch than inductive loads (motors & appliances).
  • akalatiakalati Posts: 31
    edited 2010-11-18 08:03
    kwinn wrote: »
    Since you say "wall switch" I assume this could be used one or more incandescent bulbs. I would suggest several bulbs and switches in parallel to select the load. Least expensive solution I have found.

    kwinn, I tend to agree, and that's the path I've taken, but thought there may be a simple.cheap device that does this simulation for us. In that case, is there a fixture that will do this elegantly/compactly? Maybe some sort of 6+ bulb fixture that gives an on/off switch for each bulb so that you don't have to physically screw/unscrew the bulb to test?
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2010-11-18 08:37
    I found 100 watt resistors to be quite expensive, but a 1500watt electric space heater can provide a much larger resistive load - often has a high, medium, and low load as well. Just buy one without a fan to avoid inductive loads. Some are 1200 watts with only two elements.
  • kwinnkwinn Posts: 8,697
    edited 2010-11-18 11:24
    akalati wrote: »
    kwinn, I tend to agree, and that's the path I've taken, but thought there may be a simple.cheap device that does this simulation for us. In that case, is there a fixture that will do this elegantly/compactly? Maybe some sort of 6+ bulb fixture that gives an on/off switch for each bulb so that you don't have to physically screw/unscrew the bulb to test?

    I have used "J type" or "T3 type" quartz halogen bulbs (approx 1/4" dia. x 4" long) with regular house light switches to make variable 120V loads. The bulbs are available in several wattage's up 500W and possibly higher. Makes for a simple, compact, and inexpensive load center.
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