post your load testers!

My load tester :

HEATER CARTRIDGE @ 100W X 3

Thermal switch

Copper Plate @ 50mm x 51mm / 16mm Thickness

Transformer Variable

http://i275.photobucket.com/albums/j...d_tester_1.jpg

http://i275.photobucket.com/albums/j...d_tester_5.jpg

http://i275.photobucket.com/albums/j...d_tester_2.jpg

http://i275.photobucket.com/albums/j...d_tester_3.jpg

http://i275.photobucket.com/albums/j...d_tester_4.jpg

Here are my load testers:

http://img18.imageshack.us/img18/1692/p1100250a.jpg

http://img14.imageshack.us/img14/2833/p1100252u.jpg

Left one - was used as 150W connected to 150VAC 12V transformer. But could be more when using 15-16V power supply (240-270W). Two 0.47R resistors connected in series.

Right - my latest build :up: Four 220R resistors, connect in series and parallel, which gives 220R total resistance. 240W, when using 230V.

Still a work in progress because real work gets in the way :(

http://www.brittech.co.uk/testdie.jpg

The actual heater core hand made niachrome around ceramic insulator heating a copper core and outer copper shell and wrapped in fiberglass and wiremesh heatshield to make sure all the heat goes to the target.

Heater core is 2ohm and built originally for a 12/28v 400Watt power supply unlucky for me company burn't down before I purchased PSU.

Ended up with old HP one in the pick which gives me upto 800Watts

Engineered for all Air cooled heatsinks / watercooling blocks & phase change.

I'll get it finished one day.

I can't tell for sure but you should measure the load between the catridges and the Variac. If you measure between the variac and the wall recepticle your reading will be skewed by the ineffency of the transformer.

PWM: It doesn't inspire confidence if the manufacturer of the heater burnt down. :P

wdrzal is correct regarding the measurement position, the only case when that is wrong is when using an in-line energy meter as the lower supply voltage may cause incorrect readings or no readings at all.

Quote:

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Originally Posted by yngndrw

PWM:

wdrzal the only case when that is wrong is when using an in-line energy meter as the lower supply voltage may cause incorrect readings or no readings at all.

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My orginal statement in above post is never wrong,:) If you using a inline meter that can't read the voltages & amps or wattage on the secondary side of your transformer for any reason......Get a meter that can.:up:

Ps: you need test equiptment you trust that stays in calibration.

Quote:

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Originally Posted by wdrzal

My orginal statement in above post is never wrong,:) If you using a inline meter that can't read the voltages & amps or wattage on the secondary side of your transformer for any reason......Get a meter that can.:up:

Ps: you need test equiptment you trust that stays in calibration.

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Walt can you show an example...even a simple drawing would be helpful.

Going to make this load tester in ~ 1 week. I already have 3 of the pieces finished. just the easiest piece, the plastic piece, needs to be machined.
Here are renders-
http://i198.photobucket.com/albums/a...oadtester1.jpg
http://i198.photobucket.com/albums/a...oadtester2.jpg

Looks good, maybe I'll replace my old block when that's done! I just got a new purdy variac.

Quote:

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Originally Posted by sdumper

Walt can you show an example...even a simple drawing would be helpful.

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Scott I didn't see your question until this thread was bumped today.


If you plug your watt meter into a wall receptacle and then plug your variac (transformer) into it, your watt meter will read total current,including the inefficiency of the transformer. Since transformers are not 100% efficient and their efficiency varies ,your reading will be higher than the actual load than if you measure current between transformer & load cell.

For a higher degree of accuracy measure the current between the transformer and load tester.

Your using resistive heating cartridges ,the electricity is converted to heat @ ~99.98% efficiency, so call it 100% unless you care about a small fraction of a watt error............

You will get a much more accurate reading of actual heat being produced if you measure after transformer.

Yep, that is true.
I tested this a while back, I'm sure it's still up in some thread.
At 300W at a load tester, post Variac I was reading 294W, with 300W at the wall.

New parts for load testers: :)

Heater with K-type thermal probe integrated. 0 - 250W

http://ld-phasechange.com/images/load_tester/2.JPG

http://ld-phasechange.com/images/load_tester/3.JPG

Normal: 0 - 315W and 0 - 400W.

http://ld-phasechange.com/images/load_tester/4.JPG


Kind Regards

Fantastic :eek: I do want one! :D

Thanks Walt!!

Off Topic:
Hey Tiborrr good to see you around again! I miss reading your build threads.

Hey buddy! Yeah, the six-month mandatory active full-time job in the industry/engineering bureau is taking it's toll. Tommorrow's the last day before a month long break. I'll commit it to the upcoming 2-stage auto-cascade build :)

Best Regards to my fellow XS buddies,
Niko :up: