As some of you know from my other email strings, I have been digging into the new 2nd edition UL61010A-1. I need to determine the test voltages (AC high pot) for each circuit and need your help understanding the approach. UL61010A-1 is different in a number of ways - particularyly the tables out of annex D are gone and the rational pushed into mostly section 6. As an example I am trying to determine the High pot requirements for my power supply input circuit. I have given up on the single basic approach for now. Using table 4 for mains the single basic C&C is 3mm. Double that for Reinforced and I get 6mm. The Voltage test section has a table 9 which shows the spacing of single basic versus test voltage. A very important sentence says that one takes the single basic test voltage an multiplies it X 1.6. There are two ways one good interpret this statement: 1) Take the basic barrier value of 3mm - find coresponding test voltage and multiply it times 1.6. From memory I think this is 2210 X 1.6 = 3536. This makes sense to me in that one would have excess C&C as a safety margin and the values are similar to those found in annex D of the first edition. 2) Take the basic barrier value of 6mm - find the coresponding test voltage and multiply it times 1.6. I do not have the exact values in memory but this pushes the test voltage > 5K. This does not make sense in that the C&C limit is too tight to support the test voltage and does not follow the first edition limits. Hopefully approach 1 is correct and I can sleep better. If not then I do not understand the rational for the high test voltages. Approach number 2 appears to be double jeporday - first doubling the C&C and then adding extra test voltage on top of that. Also If one has a grounded chassis but trying to support double basic isolation to the power supply secondary does this push the design to have double basic isolation relative to the chassis too? The standard says that the chassis C&C only needs to be single Basic but I suspect I must design to my weekest link and make all of it 6mm? Same question for Y caps. Would this push me from Y2 to Y1? The Y caps are grounded to the PCB ground plain which is bonded well to the chassis. I have asked these questions of our UL representative but the answer is slow in coming. Ultimately they will be my ultimate answer but I would appreciate any insight in the meantime. Regards Chris Wells [email protected]
