Ghery, I was hoping my response would get a discussion going and am pleased that you responded. Please be aware, however that the basic message I wanted to get across is that while there are clear passes (#1) and clear failures (#9); there are also gray areas. In these gray areas, whether the EUT is found compliant or not depends on a number of factors and is subject to interpretation. If the manufacturer wishes to use a permissible loss of performance, it is best to have this information submitted before the test is performed to avoid the appearance of changing the rules after the game has started in order to come out a winner! There are also subtle differences in the criteria B definition from standard to standard, and even in the same standard, depending on the equipment type. Our products are certified both to 55024 & EN 300 386 V 1.3.1. I was not familiar with the 61000-6-2 standard that Ralph inquired about but I reviewed the definition of criteria B in that standard before I responded. In each standard criteria B is applicable for transient phenomena such as ESD and allows for some degradation. However, the wording differs in each standard, which can affect compliance for “gray area” type test results. Even in CISPR 24, if you are required to use specific criteria for TTE included in Annex. A, the criteria is different and may possibly affect compliance. 61000-6-2 Criteria B: “The apparatus shall continue to operate as intended after the test. No degradation of performance or loss of function is allowed below a performance level specified by the manufacturer, when the product is used as intended. The performance level may be replaced by a permissible loss of performance. During the test, degradation of performance is however allowed. No change of actual operating state or stored data is allowed. If the minimum performance level or permissible performance loss is not specified by the manufacturer, either of these may be derived from what the user may reasonably expect from the apparatus if used as intended.” Note that the above wording does not allow changes in operating state or stored data either during or after the test. In this regard the 61000-6-2 criteria is more severe than the general CISPR 24 criteria. Thus, I stand by my initial e-mail’s #5. Under 61000-6-2 Criteria B, if the EUTs stored data or operating state changes as a result of the transient test, the EUT is non-compliant. For telecommunication network (switching) equipment under 300 386 v 1.3.1 paragraph 11.3.1.2; it is permissible for data errors to occur as a result of transient phenomena, however except for a specific exception for surge testing, established connections must be maintained throughout the testing. Thus the result Ralph described is: 1. Compliant under the general CISPR 24 criteria B 2. Non-compliant under CISPR 24 Annex A criteria B (TTE w/digital interface, TTE w/analog interfaces, FAX) 3. Compliant under CISPR 24 Annex B criteria B (data processing equipment) 4. In a gray area under 61000-6-2 5. Non-compliant under 300 386 V 1.3.1 for telecom. switching equipment The above list is partial, but I think my point is clear. Note that CISPR 24 has 7 Annexes for specific categories of ITE with operating criteria for immunity testing specifically tailored for each equipment type. Thanks to Ralph for presenting such an interesting test result example! Douglas G. Frazee Regulatory Compliance Manager Lucent Technologies PSAX Division [email protected]
From: Pettit, Ghery [mailto:[email protected]] Sent: Thursday, April 24, 2003 4:51 PM To: 'Frazee, Douglas (Douglas)'; Pettit, Ghery; 'Ralph McDiarmid'; 'EMC-PSTC' Subject: RE: Performance Criterion I'm going to contest this, but only slightly. CISPR 24 defines Performance criterion B as: "After the test, the equipment shall continue to operate as intended without operator intervention. No degradation of performance or loss of function is allowed, after the application of the phenomena below a performance level specified by the manufacturer, when the equipment is used as intended. The performance level may be replaced by a permissible loss of performance. During the test, degradation of performance is allowed. However, no change of operating state or stored data is allowed to persist after the test. If the minimum performance level (or the permissible performance loss) is not specified by the manufacturer, then either of these may be derived from the product description and documentation, and by what the end user may reasonably expect from the equipment if used as intended." Note that the change in operating state or stored data is a bit different than quoted by Doug. Obviously communications will be disrupted while the product re-boots, but re-sends should be possible and self-recovery would progress. Unless the recovery period was too long for the manufacturer to tolerate I would not call this a failure. In any case, what is and is not a failure is not clear cut. If the manufacturer is willing to allow the product to take a minute to recover, and the product does so without operator intervention, then a PASS is appropriate. If the manufacturer specifies that the product should recover more rapidly, then a FAIL is appropriate. I say nothing in the original message that indicated that there were any problems caused by the test, other than a crash that self recovered. Based on that limited information, I would call this product compliant and go on to the next test. Remember that the original message was suggesting that any loss of functionality was a failure, even though the product self recovered. If this is a manufacturer's expectation, then call it a failure. If this was a misunderstanding of criterion B, then we have this discussion. Doug, your point 9 would be a failure under criterion C, not just B. ;-) Ghery S. Pettit Intel Corporation From: Frazee, Douglas (Douglas) [mailto:[email protected]] Sent: Thursday, April 24, 2003 1:32 PM To: 'Pettit, Ghery'; 'Ralph McDiarmid'; 'EMC-PSTC' Subject: RE: Performance Criterion Ralph, Ghery's response is somewhat correct, however I'd like to add several points. The definition of criterion B in 61000-6-2 allows degradation during the immunity test. It also states that, "No change of operating state or stored data is allowed." Thus, if communications are interrupted as a result of the ESD forcing a reboot, corrupting stored data, etc.; the EUT is non-compliant. Further, if the manufacturer has not specified a permissible performance loss (test plan is helpful here); it is appropriate to consult the user manual, product specifications and/or derive the minimum performance level" from what the user may reasonably expect from the apparatus when used as intended." This opens it up to interpretation! What is the impact of a 1-minute loss of communications, is it no impact, a minor annoyance or is it likely to set off an unpleasant chain reaction or cause a hazardous condition? I'm afraid that under the condition you describe, compliance may not be clear cut. Here's a summary of my interpretations: 1) EUT completely unaffected by ESD - compliant. 2) EUT shows degradation as a direct result of ESD, self-recovers immediately, operating state and stored data is unaffected - compliant. 3) EUT shows degradation as a direct result of ESD, operating state and stored data are unaffected, EUT self-recovers but not immediately. Manufacturer has defined a permissible performance level either in general or as a result of ESD or transient electromagnetic phenomena. Observed degradation is acceptable within the manufacturer defined parameters - compliant. 4) EUT shows degradation as a direct result of ESD, operating state and stored data are unaffected, EUT self-recovers but not immediately. Manufacturer has defined a permissible performance level either in general or as a result of ESD or transient electromagnetic phenomena. Observed degradation is not acceptable within the manufacturer defined parameters - non-compliant. 5) EUT shows degradation as a direct result of ESD, operating state and/or stored data are affected. - non-compliant. 6) EUT shows degradation as a direct result of ESD, operating state and stored data are unaffected, EUT does not self-recover. - non-compliant. 7) EUT shows degradation as a direct result of ESD, operating state and stored data are unaffected, EUT self-recovers but not immediately. Manufacturer has not defined a permissible performance level either in general or as a result of ESD or transient electromagnetic phenomena. Minimum performance level is determined from EUT documentation and/or from what the user may reasonably expect from the apparatus when used as intended. Observed degradation is not acceptable within the parameters of minimum acceptable performance - non-compliant. 8) EUT shows degradation as a direct result of ESD, operating state and stored data are unaffected, EUT self-recovers but not immediately. Manufacturer has not defined a permissible performance level either in general or as a result of ESD or transient electromagnetic phenomena. Minimum performance level is determined from EUT documentation and/or from what the user may reasonably expect from the apparatus when used as intended. Observed degradation is acceptable within the parameters of minimum acceptable performance -compliant. 9) EUT releases smoke as a result of ESD infusion, shows no signs of life after test - non-compliant. 10) EUT shows degradation as a direct result of ESD, operating state and stored data are unaffected, EUT self-recovers but not immediately. Manufacturer has not defined a permissible performance level either in general or as a result of ESD or transient electromagnetic phenomena. Minimum performance level is determined from EUT documentation and/or from what the user may reasonably expect from the apparatus when used as intended. Observed degradation is acceptable within the parameters of minimum acceptable performance however tester is having a lousy day - non-compliant. Douglas G. Frazee Regulatory Compliance Manager Lucent Technologies PSAX Division [email protected] From: Pettit, Ghery [mailto:[email protected]] Sent: Thursday, April 24, 2003 11:13 AM To: 'Ralph McDiarmid'; 'EMC-PSTC' Subject: RE: Performance Criterion Ralph, If a product self-recovers without operator intervention, then you can say it meets criterion B. The manufacturer has the ability within these criteria to define the acceptable loss of function, as well. If 1 minute is an acceptable time for the self-recovery, the product passes. If operator intervention was required, then a clear failure of criterion B would exist. Ghery Pettit From: Ralph McDiarmid [mailto:[email protected]] Sent: Wednesday, April 23, 2003 5:01 PM To: 'EMC-PSTC' Subject: Performance Criterion I have a question about Performance Criterion B as described in EN61000-6-2. Scenario: A product temporary looses communication over a network connection during an EMC disturbance like an ESD event. It self-recovers and resumes communication after about a minute. Question: Is the above event considered an acceptable loss of performance or a loss of functionality? If it is a loss of functionality, even a temporary one, then I would say that is fails Criterion B, but meets Criterion C. I don't think it a question of loss of performance in this example. Is this a correct interpretation? Thanks, Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc.
