I will need to operate the new, Hi-Pot tester, an SCI 294, before designing an OHAI test procedure. The tester should be delivered to Aleph Objects on Friday, April 27. As I am out on PTO that day, I will set up and operate the SCI 294 first thing Monday morning. Based on my observations with the tester, I can write up a proper test procedure.
The main issues involved with the UL test are safety related. The test involves the SCI 294 putting 1000 VDC on the AC power inputs of the printer. Special care must be used by the test operator to insure that he/she is not in contact with the printer when running the test and that all other personnel stay away from the test area.
- Does each unit need to be tested with the cord it will ship with?
- We were told the test should be on each fully assembled unit, before it is boxed. @mjpelletier suggested before calibration. However the machine isn't technically fully assembled until part way through calibration as the bed plate is installed during Calibration step 3. Can the bed plate be left off for this test?
- I would suggest testing the printer with the cord it is be be shipped with. That will insure that the entire assembly is safe.
- I'm not sure what the whole assembly process is but we want to Hi-Pot test units that are as complete as possible. Also, a functional test should be performed on the printers after Hi-Pot testing to make sure they have not been damaged or affected by the Hi-Pot test.
@mjpelletier The info I received from @bowman (and @Steven) indicates that since our power cables are already UL tested/certified we shouldn't need to test them.
The calibration OHAI will be re-ordered so that the fasteners underneath the bed plate are verified before then installing the bed plate and performing Hi-Pot testing. The machine will then go through the remaining calibration tests as normal.
We won't have to test each power cord that is shipped with EU's/AU's.
However, we should test using the exact same power cord that is used for burn-in/calibration and shipped with the printer.
We are setting up the 5th calibration bench (near lamination) as a "Calibration PREP" station.
At the prep station, we would perform the following:
- Verify the fasteners underneath the bed.
- Install heat bed to spec.
- Install the power cord that will be used/shipped with the printer.
- Run Hi-Pot test.
- Passing units forward on to complete calibration/testing. (with the tested power cord/heat bed going with unit)
- Failing units are tagged, evaluated for cause and corrected.
Regarding power cables, my only concern is using the same power cable for repeated tests may eventually cause the cable's insulation to fail. The power cord should pass a 1500 VDC test for 60 seconds but may degrade after multiple 60 second tests. This type of test over-stresses components. Our normal power cables are marked as being rated at 300V.
@mjpelletier I think we should be good then, the only two cords we cant test are AU/EU, but each AU/EU ships with a UK that WILL be tested with. So NA they will test with the NA power cord that ships with the printer. For EU/AU shipments they will test with the UK cable to be shipped with that machine as that cable is also used during calibration and burn-in testing of machines shipped to AU/EU.
This has been added to Calibration OHAI step 2 here: https://ohai.lulzbot.com/project/calibration-mini2/mini-2/
Please review the posted instructions and let me know if any revision is necessary.
Photos pending per T2486