Fully Insulated Wire

Breakdown Voltage Calculation acc. to FIW Standard IEC 60317-0-7

Test is done by cylinder BDV test acc. to IEC 60851-4.3.2. The minimum breakdown voltage has to be calculated for every specific FIW wire size using the increase by insulation and the specific V/µm-value from below table.

Nominal conductor diameter
mm		 Minimum specific breakdown voltage
V/µm increase
over up to and including at room temperature at 180°C
- - >0.100 81 56
0.100 0.355 76 53
0.355 0.500 70 49
0.500 1.000 53 37
1.000 1.600 47 33
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NOTE: The specific breakdown voltage is the result of the quotient of the measured value and enamel increase.

Example of formula for calculation of breakdown voltage (BDV):

BDV = min. increase *min. spec. BDV in V/μm

Example: 0.2 mm FIW6 with min. OD 0.303 mm

min. increase = min. OD - nom. dia. = 0.303 mm - 0.2 mm = 0.103 mm = 103 μm

=> BDV = 103 μm x 76 V/μm = 7828 V

Calculated Minimum Breakdown Voltage at 20 °C acc. to FIW Standard IEC 60317-56

FIW3 FIW4 FIW5 FIW6 FIW7 FIW8 FIW9
Nominal
Diameter		 min min min min min min min
[mm] [V] [V] [V] [V] [V] [V] [V]
0.071 1701 2187 3240 4293 5346 6399 7452
0.080 1782 2349 3483 4617 5751 6885 8019
0.090 1944 2511 3645 4779 5913 7047 8181
0.100 2106 2673 3969 5265 6561 7857 9153
0.106 2052 2660 3952 5244 6536 7828 9120
0.112 2128 2736 4028 5320 6612 7904 9196
0.118 2128 2812 4180 5548 6916 8284 9652
0.120 2280 2964 4332 5700 7068 8436 9804
0.125 2280 2964 4332 5700 7068 8436 9804
0.132 2356 3040 4560 6080 7600 9120 10640
0.140 2432 3192 4712 6232 7752 9272 10792
0.150 2508 3344 5016 6688 8360 10032 11704
0.160 2660 3496 5168 6840 8512 10184 11856
0.170 2736 3648 6232 8056 9880 11704 13528
0.180 2888 3800 5624 7448 9272 11096 12920
0.190 2964 3876 5776 7676 9576 11476 13376
0.200 3040 4028 5928 7828 9728 11628 13528
0.212 3268 4332 6384 8436 10488 12540 14592
0.220 3268 4332 6384 8436 10488 12540 14592
0.224 3268 4332 6384 8436 10488 12540 14592
0.236 3572 4788 7068 9348 11628 13908 16188
0.250 3648 4788 7068 9348 11628 13908 16188
0.265 3800 5016 7372 9728 12084 14440 16796
0.280 3800 5016 7372 9728 12084 14440 16796
0.300 4028 5320 7676 10032 12388 14744 17100
0.315 4028 5320 7676 10032 12388 14744 17100
0.330 4332 5624 7980 10336 12692 15048 17404
0.335 4332 5624 7980 10336 12692 15048 17404
0.350 4332 5624 7980 10336 12692 15048 16030
0.355 4332 5624 7980 10336 12692 15048 16030
0.375 4200 5530 7700 10290 12460 14630
0.400 4200 5530 7700 9870 12040 14210
0.425 4480 5880 8050 10220 12390 14560
0.450 4480 5880 8050 10220 12390 14560
0.475 4690 6160 9030 11900 14770 17640
0.500 4690 6160 9030 11900 14770
0.530 3710 4982 7155 9328 11501
0.550 3763 4982 7155 9328 11501
0.560 3763 4982 7155 9328 11501
0.600 3975 5247 7420 9593 11766
0.630 3975 5247 7420 9593 11766
0.650 4240 5565 7738 9911 12084
0.670 4240 5565 7738 9911 12084
0.710 4240 5565 7738 9911 12084

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Breakdown Voltage Calculation acc. to Transformer Standard IEC 61558-1

U=OD - Cu∅ x V/µm x 10³ x 0.85    (at 180°C for 60 seconds)

FIW3 FIW4 FIW5 FIW6 FIW7 FIW8 FIW9
Nominal
Diameter		 min min min min min min min
[mm] [V] [V] [V] [V] [V] [V] [V]
0.040 714 904 1428 1904 2380 2856
0.045 809 1047 1618 2142 2666 3189
0.050 809 1095 1618 2142 2666 3189
0.056 904 1238 1761 2332 2904 3475
0.063 1000 1285 1904 2523 3142 3760
0.071 1000 1285 1904 2523 3142 3760 4379
0.080 1047 1380 2047 2713 3380 4046 4712
0.090 1142 1476 2142 2808 3475 4141 4808
0.100 1238 1571 2332 3094 3856 4617 5379
0.112 1261 1622 2388 3154 3919 4685 5451
0.125 1352 1757 2568 3379 4190 5001 5811
0.140 1442 1892 2793 3694 4595 5496 6397
0.160 1577 2072 3063 4055 5046 6037 7028
0.180 1712 2253 3334 4415 5496 6577 7659
0.200 1802 2388 3514 4640 5766 6893 8019
0.224 1937 2568 3784 5001 6217 7433 8650
0.250 2162 2838 4190 5541 6893 8244 9596
0.280 2253 2973 4370 5766 7163 8560 9956
0.315 2388 3154 4550 5947 7343 8740 10136
0.355 2568 3334 4730 6127 7523 8920 10316
0.400 2499 3290 4582 5873 7164 8455
0.450 2666 3499 4790 6081 7372
0.500 2791 3665 5373 7081 8788
0.560 2233 2956 4246 5535 6825
0.630 2359 3114 4403 5692 6982
0.710 2516 3302 4592 5681 7171
0.800 2673 3522 5126 6730
0.900 2831 3743 5347 6950
1.000 2988 3931 5535 7139
1.120 2749 3618 5330
1.250 2805 3703 5414
1.400 2889 3815 5526
1.600 3001 3955 5666
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Minimum BDV acc. IEC 62368

Nominal conductor diameter Minimum specific breakdown voltage Minimum overall FIW diameter
do [mm]		 Minimum dielectric strength test voltage values per wire for basic or reinforced insulation at overall diameter. Us [V] (duration of 60 s)
dCu [mm] Ub [V/μm] Grade of FIW 3 Grade of FIW 4 Grade of FIW 5 Grade of FIW 6 Grade of FIW 7 Grade of FIW 8 Grade of FIW 9 Grade of FIW 3 Grade of FIW 4 Grade of FIW 5 Grade of FIW 6 Grade of FIW 7 Grade of FIW 8 Grade of FIW 9
0.04 56 0.055 0.059 0.070 0.080 0.090 0.100   714 904 1428 1904 2380 2856  
0.045 56 0.062 0.067 0.079 0.090 0.101 0.112   809 1 047 1 618 2 142 2 666 3 189  
0.05 56 0.067 0.073 0.084 0.095 0.106 0.117   809 1095 1618 2142 2666 3189  
0.056 56 0.075 0.082 0.093 0.105 0.117 0.129   904 1238 1761 2332 2904 3475  
0.063 56 0.084 0.090 0.103 0.116 0.129 0.142   1000 1285 1904 2523 3142 3760  
0.071 56 0.092 0.098 0.111 0.124 0.137 0.150 0.163 1000 1285 1904 2523 3142 3760 4379
0.08 56 0.102 0.109 0.123 0.137 0.151 0.165 0.179 1047 1380 2047 2713 3380 4046 4712
0.09 56 0.114 0.121 0.135 0.149 0.163 0.177 0.191 1142 1476 2142 2808 3475 4141 4808
0.1 56 0.126 0.133 0.149 0.165 0.181 0.197 0.213 1238 1571 2332 3856 3856 4617 5379
0.112 53 0.140 0.148 0.165 0.182 0.199 0.216 0.233 1261 1622 2388 3154 3919 4685 5451
0.125 53 0.155 0.164 0.182 0.200 0.218 0.236 0.254 1352 1757 2568 3379 4190 5001 5811
0.14 53 0.172 0.182 0.202 0.222 0.242 0.262 0.282 1442 1892 2793 3694 4595 5496 6397
0.16 53 0.195 0.206 0.228 0.250 0.272 0.294 0.316 1577 2072 3063 4055 5046 6037 7028
0.18 53 0.218 0.230 0.254 0.278 0.302 0.326 0.350 1712 2253 3334 4415 5496 6577 7659
0.2 53 0.240 0.253 0.278 0.303 0.328 0.353 0.378 1802 2388 3514 4640 5766 6893 8019
0.224 53 0.267 0.281 0.308 0.335 0.362 0.389 0.416 1937 2568 3784 5001 6217 7433 8650
0.25 53 0.298 0.313 0.343 0.373 0.403 0.433 0.463 2162 2838 4190 5541 6893 8244 9596
0.28 53 0.330 0.346 0.377 0.408 0.439 0.470 0.501 2253 2973 4370 5766 7163 8560 9956
0.315 53 0.368 0.385 0.416 0.447 0.478 0.509 0.540 2388 3154 4550 5947 7343 8740 10136
0.355 53 0.412 0.429 0.460 0.491 0.522 0.553 0.584 2568 3334 4730 6127 7523 8920 10316
0.4 49 0.460 0.479 0.510 0.541 0.572 0.603   2499 3290 4582 5873 7164 8455  
0.45 49 0.514 0.534 0.565 0.596 0.627 0.658   2666 3499 4790 6081 7372    
0.5 49 0.567 0.588 0.629 0.670 0.711     2791 3665 5373 7081 8788    
0.56 37 0.631 0.654 0.695 0.736 0.777     2233 2956 4246 5535 6825    
0.63 37 0.705 0.729 0.770 0.811 0.852     2359 3114 4403 5692 6982    
0.71 37 0.790 0.815 0.856 0.897 0.938     2516 3302 4592 5881 7171    
0.8 37 0.885 0.912 0.963 1.014       2673 3522 5126 6730      
0.9 37 0.990 1.019 1.070 1.121       2831 3743 5347 6950      
1 37 1.095 1.125 1.176 1.227       2988 3931 5535 7139      
1.12 33 1.218 1.249 1.310         2749 3618 5330        
1.25 33 1.350 1.382 1.443         2805 3703 5414        
1.4 33 1.503 1.536 1.597         2889 3815 5526        
1.6 33 1.707 1.741 1.802         3001 3955 5666        
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Comments on Different BDV Standards
  • The actual version of the Transformer Standard IEC 61558-1 gives much lower values than IEC 60317-0-7.
  • The specific voltage per micron is given acc. to IEC 60317-0-7 at room temperature, while IEC 61558 calculates values of 180 °C and a safety margin (0.85). Actually needed temperature of SMPS (Switch Mode Power Supply) is somewhere in between.
  • IEC 62368 follows the BDV values of IEC 61558, but does not specify 180 °C as test temperature as IEC 61558.