RE: Verifying functionality of the equipment for Production Safet y Testing
Mike, How does the maximum leakage or touch current for the product fit into all of this? ITE has a 3.5 mA maximum requirement which is measured during the evaluation. This measurement should be looking at the system parasitic as well as designed capacitance in the system. The hi-pot tester shouldn't be able to generate more leakage current than the system has designed into it. It is only a gross check of the primary to ground insulation system and pretty much of a digital thing, it either holds or doesn't Gary -Original Message- From: mike harris [mailto:tecco...@i-cafe.net] Sent: Tuesday, September 26, 2000 10:21 PM To: Ron Pickard; paul_j_sm...@notes.teradyne.com Cc: emc-p...@ieee.org Subject: Re: Verifying functionality of the equipment for Production Safety Testing Hi All, This exchange prompts me to mention a recurring theme that began over 30 years ago, when I transitioned from MIL-SPEC hipot testing, where hipot leakage was specified, to UL hipot where leakage was not specified. At that time I was incredulous that UL did not specify what seemed to me critical factor, but it was explained that with a 500VA hipot, breakdown would be obvious. As hipots got smaller, UL said that less than 500 VA could be used if there was a voltmeter at the output to assure voltage was applied for the full duration, and a reliable means to indicate breakdown. In the early days that means was often a current-sensing relay to detect some level of excessive leakage. Hipots got progressively smarter, using microprocessors and circuits to distinguish non-linear changes in leakage, but also circuits to distinguish between capacitive leakage (typically from mains capacitors in switching supplies) and arc-over currents. Some units have capacitive leakage of over 20mA, so a hipot with lower current capabilities will indicate "failure". Testing with a more powerful AC hipot, or with a DC hipot, might allow the same unit to pass. My concern is that UL (and the similar agencies) still does not specify a maximum leakage, so any effort to use resistors for calibrating a hipot appears to me to be setting a leakage standard that may have more to do with the hipot current capability than its arc-over breakdown detection capabilities. Resistors are convenient, no doubt, but I suggest that the true measure of the hipot's ability to detect breakdown is either a) a controlled spark gap or b) an avalance current detector which looks for an exponential rate of rise of current rather than just the level of current. This topic continues to be a source of debate within UL as recently as last week. Comments? Mike Harris/Teccom -Original Message- From: Ron Pickard To: paul_j_sm...@notes.teradyne.com Cc: emc-p...@ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Tuesday, September 26, 2000 12:11 PM Subject: Re: Verifying functionality of the equipment for Production Safety Testing > > >Hi Paul, > >First, I would caution you from holding the hipot test lead while the tester is in operation. It >could certainly be hazardous to your health, and all that. I wonder if this is one of those "don't >try this at home" cases. > >Anyway, in another life while undergoing an initial BABT 340 quality system audit, the auditor asked >us "How do we know that the tester is working properly, and how do you know the tester will give a >failure indication when expected?" Well, these were questions we had not anticipated and were >unprepared with a quick answer. To meet the auditor's challenge, however, we fashioned a setup that >verified the complete tester, including cables. This verification setup included 2 resistors (one >for hipot and the other for ground continuity). The values for each resistor were selected so that >the testers would indicate a failure at just over the current trip point of each tester. To verify >the setup each day, the testers were tested using these resistors (a failure indication was a pass >and a pass indication was a failure). The resistors and the test equipment were all placed on a >routine calibration cycle. This satisfied BABT and other safety agencies that performed the >facility/product audits. > >I hope this helps. > >Best regards, > >Ron Pickard >rpick...@hypercom.com > > > >--- >This message is from the IEEE EMC Society Product Safety >Technical Committee emc-pstc discussion list. > >To cancel your subscription, send mail to: > majord...@ieee.org >with the single line: > unsubscribe emc-pstc > >For help, send mail to the list administrators: > Jim Bacher: jim_bac...@mail.monarch.com > Michael Garretson:pstc_ad...@garretson.org > >For policy questions, send mail to: > Richard Nute: ri...@ieee.org > > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mai
RE: Verifying functionality of the equipment for Production Safet y Testing
In past lives I've done exactly what Ron is suggesting, plus we had a "golden" unit for the start of production shift testing. We tested the "golden" unit and it should pass, the test jig was then tested and all of the audible and visual indicators were examined to insure that they all were operating. The status of both units and tests was inserted into the test log and initialed by the operator. Same guy that had to indicate the serial numbers and date of the tests for each of the products. We have found instances where one or more of the indicators failed to show a fault. A lamp was burned out etc. Gary -Original Message- From: Ron Pickard [mailto:rpick...@hypercom.com] Sent: Tuesday, September 26, 2000 11:12 AM To: paul_j_sm...@notes.teradyne.com Cc: emc-p...@ieee.org Subject: Re: Verifying functionality of the equipment for Production Safety Testing Hi Paul, First, I would caution you from holding the hipot test lead while the tester is in operation. It could certainly be hazardous to your health, and all that. I wonder if this is one of those "don't try this at home" cases. Anyway, in another life while undergoing an initial BABT 340 quality system audit, the auditor asked us "How do we know that the tester is working properly, and how do you know the tester will give a failure indication when expected?" Well, these were questions we had not anticipated and were unprepared with a quick answer. To meet the auditor's challenge, however, we fashioned a setup that verified the complete tester, including cables. This verification setup included 2 resistors (one for hipot and the other for ground continuity). The values for each resistor were selected so that the testers would indicate a failure at just over the current trip point of each tester. To verify the setup each day, the testers were tested using these resistors (a failure indication was a pass and a pass indication was a failure). The resistors and the test equipment were all placed on a routine calibration cycle. This satisfied BABT and other safety agencies that performed the facility/product audits. I hope this helps. Best regards, Ron Pickard rpick...@hypercom.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Verifying functionality of the equipment for Production Safet y Testing
I agree with Ron . . . When I was the BABT ALE (Aproval Liaison Engineer) with my last company, the same issue arose during my intitial BABT audit with verifying the Hi-Pot tester's proper operation. I too fashioned a device (used a plastic box with terminals and internal resistors) to test the Hi-Pot tester prior to it's being put into service on a daily basis. That is the way to go . . . inexpensive & easy. John Juhasz Fiber Options Bohemia, NY -Original Message- From: Ron Pickard [mailto:rpick...@hypercom.com] Sent: Tuesday, September 26, 2000 2:12 PM To: paul_j_sm...@notes.teradyne.com Cc: emc-p...@ieee.org Subject: Re: Verifying functionality of the equipment for Production Safety Testing Hi Paul, First, I would caution you from holding the hipot test lead while the tester is in operation. It could certainly be hazardous to your health, and all that. I wonder if this is one of those "don't try this at home" cases. Anyway, in another life while undergoing an initial BABT 340 quality system audit, the auditor asked us "How do we know that the tester is working properly, and how do you know the tester will give a failure indication when expected?" Well, these were questions we had not anticipated and were unprepared with a quick answer. To meet the auditor's challenge, however, we fashioned a setup that verified the complete tester, including cables. This verification setup included 2 resistors (one for hipot and the other for ground continuity). The values for each resistor were selected so that the testers would indicate a failure at just over the current trip point of each tester. To verify the setup each day, the testers were tested using these resistors (a failure indication was a pass and a pass indication was a failure). The resistors and the test equipment were all placed on a routine calibration cycle. This satisfied BABT and other safety agencies that performed the facility/product audits. I hope this helps. Best regards, Ron Pickard rpick...@hypercom.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Verifying functionality of the equipment for Production Safet y Testing
CSA requires us to run a hi-pot tester test to verify that the tester is functional, once every day on those days that we run the hi-pot tests. The log book is supposed to have entries recording this verifications. Newer testers have built-in capability to do it, for older testers some manufacturers have add-on devices to run this function. Leo Simon EMC Corp. -Original Message- From: James, Chris [mailto:c...@dolby.co.uk] Sent: Tuesday, September 26, 2000 7:33 AM To: emc-p...@majordomo.ieee.org Subject: re: Verifying functionality of the equipment for Production Safet y Testing Some Hi-pot testers have the ability to set a minimum leakage current expected which sets the alarm off if the unit being tested is switched off or otherwise disconnected. Our UL inspector expects to see a calibration log for the Hi-pot tester. It is quite easy to build a simple fixture to test a hi pot - I'll happily email a pdf to anyone interested. Chris --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
re: Verifying functionality of the equipment for Production Safet y Testing
Some Hi-pot testers have the ability to set a minimum leakage current expected which sets the alarm off if the unit being tested is switched off or otherwise disconnected. Our UL inspector expects to see a calibration log for the Hi-pot tester. It is quite easy to build a simple fixture to test a hi pot - I'll happily email a pdf to anyone interested. Chris --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Verifying functionality of the equipment for Production Safet y Testing
Some Hi-pot testers have the ability to set a minimum leakage current expected which sets the alarm off if the unit being tested is switched off or otherwise disconnected. Our UL inspector expects to see a calibration log for the Hi-pot tester. It is quite easy to build a simple fixture to test a hi pot - I'll happily email a pdf to anyone interested. Chris -Original Message- From: Rich Nute [mailto:ri...@sdd.hp.com] Sent: Monday, September 25, 2000 11:08 PM To: paul_j_sm...@notes.teradyne.com Cc: emc-p...@ieee.org Subject: Re: Verifying functionality of the equipment for Production Safety Testing Hi Paul: > My manufacturing contacts have asked for a lead on a supplier of test > equipment that I can use to be able to test the Hi pot lead for it not to > be open. If you run the Hi Pot test holding the lead in the air it will > pass . We need a way to test that the lead is not open . Connect the lead to ground and initiate the hi-pot test. ... ... ... A long time ago, I was embarrased by this situation. A UL or CSA inspector asked to verify that the hi- pot tester was indeed applying voltage to the EUT. I was about to go get a high-voltage voltmeter when the inspector simply connected the HV lead to ground and punched the start button. To my dismay, the hi-pot tester indicated pass!!! The lead was open! Well... we pulled our warehouse stock and re-tested all units. Rich --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Verifying functionality of the equipment for Production Safet y Testing
Paul, Associated Research model HyPot II 3570D, has the capability of setting a minimum current. This will ensure that there is no open. Depending on your location. I can set you up with a rep that may be able to let you "demo" in your location to see if it suits your needs. Contact me directly for more info. Josh -Original Message- From: paul_j_sm...@notes.teradyne.com [mailto:paul_j_sm...@notes.teradyne.com] Sent: Monday, September 25, 2000 2:25 PM To: EMC-PSTC (E-mail) Subject: RE: Verifying functionality of the equipment for Production Safety Testing Folks, My manufacturing contacts have asked for a lead on a supplier of test equipment that I can use to be able to test the Hi pot lead for it not to be open. If you run the Hi Pot test holding the lead in the air it will pass . We need a way to test that the lead is not open . The Test requirement (as far as I know) is to verify functionality of the equipment before testing. Best Regards, Paul J. Smith, Teradyne Kevin Harris on 09/25/2000 01:39:29 PM Please respond to Kevin Harris To: "'Maxwell, Chris'" cc: "EMC-PSTC (E-mail)" (bcc: Paul J Smith/Bos/Teradyne) Subject: RE: Battery Safety Hi, I've seen this done before on low current designs. Sometimes when you replace the batteries in this type of design the circuit voltage does not have time to drop completely away due to the charge saved on bulk capacitors. When the new batteries are added the circuit comes up in a peculiar state. This is particularly true of uP power on reset circuits. There are more elegant ways to take care of this problem but I suppose a single resistor would be the cheapest (if one ignored battery life). Regards, Kevin Harris Manager, Approval Services Digital Security Controls -Original Message- From: Maxwell, Chris [mailto:chr...@gnlp.com] Sent: Monday, September 25, 2000 11:31 AM To: 'EMC-PSTC Internet Forum' Subject: Battery Safety All, We have inherited a design from a company which we purchased. The product is a handheld and can be operated from a pair of Alkaline batteries. Inside the unit, there is a 91 KOhm resistor across the + and - terminals of the batteries. Since the people who designed the instrument are long gone, some of my collegues have asked me if this resistor could be a safety feature. I can't think of any way this resistor would help the safety of the instrument. I did read through the safety test report; and I found no reference to this resistor being required. All it does is provide a constant drain on the battery (reducing battery life). It has been suggested to me that some designers put resistors across batteries to reduce the electrical noise in a product. To me a capacitor would be better for this because it wouldn't drain the battery while it was filtering. Even so, isn't a battery the ultimate capacitor? I'm just drawing a blank why anyone would do this. I'd love to recommend that we pull this resistor out because it's a pain to solder and it affects battery life. However, I don't want to sacrifice the safety of the product. Anybody want to take a guess at this one? Thanks. Chris Maxwell, Design Engineer GN Nettest Optical Division 6 Rhoads Drive, Building 4 Utica, NY 13502 PH: 315-797-4449 FAX: 315-797-8024 EMAIL: chr...@gnlp.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ji
