Amrel PPS 2322 Calibration - Need 0.1 Ohm .001% 10W Resistor [SOLVED] - Page 1
Forum section: electronics / testgear

author: tzcczt
author_rank: Contributor
timestamp: August 15, 2014, 01:30:21 pm
content: I bought a PPS 2322 off eBay but the voltage and current display is off a bit from my Fluke 87v. The calibration is done entirely in software according to the (manual)[http://www.programmablepower.com/products/amrel/PPS/PPS-Manual.pdf] but I need a very particular resistor that I've had no luck in finding:Precision Shunt Resistor-0.1 ohm/10 Amp, 0.001% accuracy (for smaller current) or0.05% accuracy (for larger current), 20ppm, 10 wattsWhat do people typically do in these situations? I'm currently thinking about buying a 10 watt 0.1 ohm resistor with the best accuracy I can find (best I've found is 1% though).

author: Rufus
author_rank: Super Contributor
timestamp: August 15, 2014, 03:25:34 pm
content: Quote from: tzcczt on August 15, 2014, 01:30:21 pmit doesn't need a resistor. The calibration procedure is just using that resistor as a current shunt.Put your 87v on the 10A current range across the output and convert the current reading to the voltage that would be produced across a 0R1 resistor carrying that current. The calibration will then match and be as good as your 87v.

author: German_EE
author_rank: Super Contributor
timestamp: August 15, 2014, 05:07:13 pm
content: Just out of curiosity I went looking for a 0.1 ohm 0.001% resistor and the best I could find was 0.005% 0.3W which is a custom Vishay part.77.94 Euro each but if you buy ten the price drops to 65 Euro

author: wraper
author_rank: Unknown
timestamp: August 15, 2014, 05:28:08 pm
content: Such a current shunt likely will cost more than your 87v and 2322 together. So just use multimeter amps range, you are not a cal lab to do all "properly and traceable". Caveat: measure current fast until your multimeter shunt heats up and reading drifts.And to make any sense from using such precise current shunt, you need at least 6.5 digit DMM, not 87v.

author: tzcczt
author_rank: Contributor
timestamp: August 15, 2014, 06:01:03 pm
content: Thanks, I didn't think of just measuring the current directly. Regarding the accuracy, the 87v is the best meter I have. Right now the power supply is 10'ths of a volt from my meter, I'm just hoping to get it closer than that.

author: tzcczt
author_rank: Contributor
timestamp: August 15, 2014, 06:22:16 pm
content: And it looks like the entire endeavor was for naught. I'm following the manual instructions, but it won't enter calibration mode. Guessing that's how I picked it up so cheaply

author: wraper
author_rank: Unknown
timestamp: August 15, 2014, 06:27:04 pm
content: In general (don't know about this particular device) there can be some cal disable jumper on the pcb or something like that. It can be password protected (with reset jumper/dip switch somewhere inside).

author: tzcczt
author_rank: Contributor
timestamp: August 17, 2014, 01:38:09 pm
content: Quote from: wraper on August 15, 2014, 06:27:04 pmThanks for the tip, I checked though and couldn't find one.

author: G0HZU
author_rank: Super Contributor
timestamp: August 17, 2014, 01:53:57 pm
content: QuoteI'd imagine that most people who buy one of those PSUs on ebay will just plug it in and use it.QuoteNote: your thread title says that you need a 0.1Ohm 0.0001% 10W resistor. Keyboard bounce?

author: kwass
author_rank: Frequent Contributor
timestamp: August 17, 2014, 02:37:55 pm
content: Quote from: tzcczt on August 17, 2014, 01:38:09 pmI have a similar Amrel LPS-305 and can confirm that there is no calibration jumper. Mine does go into calibration mode by simultaneously pressing "8" and "minus down array" (which is in the same key position as the "on/off" button on your unit). Do you have an GP-IB port on a PC to try the remote calibration method?

author: tzcczt
author_rank: Contributor
timestamp: August 17, 2014, 05:09:49 pm
content: Quote from: kwass on August 17, 2014, 02:37:55 pmUnfortunately I've got no GPIB card, however I just figured it out the issue. I found anothermanualwhich had different calibration instructions. For the unit I have, pressing "." "0" "." in sequence puts it in calibration mode.Just finished calibration and it matches my Fluke DMM well enough. Thanks!

author: kawal
author_rank: Frequent Contributor
timestamp: May 24, 2017, 01:22:37 am
content: Thank you for the tip on the calibration procedure. I was trying the "8/on/off" and 8 with other combinations and no luck until you post.".0." saved the day.'My unit is from 1991 and last calibration sticker was from 2014.power transistors are 4 x 2N3055 (2 per channel).used my trusty 5.5D HP meter to calibrate.Current reading seams more precise than voltage reading.