FIW

Breakdown Voltage (BDV) values for FIW will vary depending upon which standard is used to calculate these values.

When using the magnet wire standards for FIW (IEC 60317-0-7 & 60317-56) the BDV is calculated using the minimum insulation increase per size. (min. insulation increase = min. OD including insulation – nominal bare wire dimension).

When using the transformer standard for FIW (IEC 61558-2-16) the BDV calculation mistakenly uses the minimum insulation increase divided in half, erroneously resulting in approximately half the BDV values as the magnet wire standards.

Therefore a new version of IEC 61558-2-16 (new version IEC 61558-1) will be released soon, correcting errors (like the BDV calculation described above) found in the previous version. One major difference: the new version will require the FIW to maintain stability for one minute longer than the magnet wire BDV standard calculation during peak voltage.

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


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. DSP 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

 

FIW Quick Selection

For the selection of the right FIW wire 

 

key in the Nominal Diameter (in mm) and the FIW Grade in the input fields underneath to calculate the Length, Weight and minimal Breakdown Voltage (acc. to IEC 60317-56) of the specified FIW wire (line 1), 

 

or key in the Nominal Diameter (in mm) and the required minimal Breakdown Voltage (acc. to IEC 60317-56) to get the corresponding FIW Grade of the FIW wire (line 2).

 

                                                  
  1. Nominal Diameter [mm] Grade
    Length [km/kg]???Weight [kg/km]???min. Breakdown Voltage [V]???

  2. Nominal Diameter [mm] min. Breakdown Voltage [V]
    Length [km/kg]???Weight [kg/km]???Grade???

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

Nominal
Diameter		FIW3FIW4FIW5FIW6FIW7FIW8FIW9
 
minminminminminminmin
[mm][V][V][V][V][V][V][V]
 
0.0711701218732404293534663997452
0.0801782234934834617575168858019
0.0901944251136454779591370478181
0.1002106267339695265656178579153
0.1062052266039525244653678289120
0.1122128273640285320661279049196
0.1182128281241805548691682849652
0.1202280296443325700706884369804
0.1252280296443325700706884369804
0.13223563040456060807600912010640
0.14024323192471262327752927210792
0.150250833445016668883601003211704
0.160266034965168684085121018411856
0.170273636486232805698801170413528
0.180288838005624744892721109612920
0.190296438765776767695761147613376
0.200304040285928782897281162813528
0.2123268433263848436104881254014592
0.2203268433263848436104881254014592
0.2243268433263848436104881254014592
0.2363572478870689348116281390816188
0.2503648478870689348116281390816188
0.2653800501673729728120841444016796
0.2803800501673729728120841444016796
0.30040285320767610032123881474417100
0.31540285320767610032123881474417100
0.33043325624798010336126921504817404
0.33543325624798010336126921504817404
0.35043325624798010336126921504816030
0.35543325624798010336126921504816030
0.375420055307700102901246014630
0.40042005530770098701204014210
0.425448058808050102201239014560
0.450448058808050102201239014560
0.475469061609030119001477017640
0.5004690616090301190014770
0.530371049827155932811501
0.550376349827155932811501
0.560376349827155932811501
0.600397552477420959311766
0.630397552477420959311766
0.650424055657738991112084
0.670424055657738991112084
0.710424055657738991112084

bold

=item available from stock

 

Breakdown Voltage Calculation acc. to Transformer Standard IEC 61558-2-16, (Edition 1.0 2013-08)

The voltages given in IEC 61558 will be modified to higher values in IEC 61558-1.

U= (OD - Cu∅) /2 x V/μm x 103  (at 180°C)

Nominal
Diameter		FIW3FIW4FIW5FIW6FIW7FIW8FIW9
 
minminminminminminmin
[mm][V][V][V][V][V][V][V]
 
0.071756109214561820218425482912
0.080784117615681960235227443136
0.090840123216242016240828003192
0.100896134417922240268831363584
0.106901135218022253270331543604
0.112928137818292279273031803631
0.118954143119082385286233393816
0.1201007148419612438291533923869
0.1251007148419612438291533923869
0.1321034156420942624315436844214
0.1401087161721472677320737374267
0.1501140172323062889347240554638
0.1601193177623592942352541084691
0.1701246188227833419405546915327
0.1801299193525713207384344795115
0.1901325198826503313397546385300
0.2001378204127033366402846915353
0.2121484220029153631434650625777
0.2201484220029153631434650625777
0.2241484220029153631434650625777
0.2361643243832334028482356186413
0.2501643243832334028482356186413
0.2651723254433664187500958306652
0.2801723254433664187500958306652
0.3001829265034724293511559366758
0.3151829265034724293511559366758
0.3301935275635784399604260426864
0.3351789254833084067482755866346
0.3501935275635784399522160426864
0.3551789254833084067482755866346
0.375191126713577433750965856
0.400191126713430419049498709
0.425203427933553431250725831
0.450203427933553431250725831
0.475213231364141514561506909
0.50021323136414151456150
0.53017212479323839964755
0.55017212479357139964755
0.56017212479357139964755
0.60018132572333040894847
0.63018132572333040894847
0.65019242683344142004958
0.67019242683344142004958
0.71019242683344142004958

 

From 2018 onwards the following table will apply:

In future, IEC 61558-2-16 will refer to IEC 61558-1 and the table in IEC 61558-2-16 will be omitted.

Breakdown Voltage Calculation acc. to Transformer Standard IEC 61558-1, (not published yet)

 

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

Nominal
Diameter		FIW3FIW4FIW5FIW6FIW7FIW8FIW9
 
minminminminminminmin
[mm][V][V][V][V][V][V][V]
 
0.0407149041428190423802856
0.04580910471618214226663189
0.05080910951618214226663189
0.05690412381761233229043475
0.063100012851904252331423760
0.0711000128519042523314237604379
0.0801047138020472713338040464712
0.0901142147621422808347541414780
0.1001238157123323094385646175379
0.1121261162223883154391946855451
0.1251352175725683379419050015811
0.1401442189227933694459554966397
0.1601577207230634055504660377028
0.1801712225333344415549665777659
0.2001802238835144640576668938019
0.2241937256837845001621774338650
0.2502162283841905541689382449596
0.2802253297343705766716385609956
0.31523883154455059477343874010136
0.35525683334473061277523892010316
0.400249932904582587371648455
0.45026663499479060817372
0.50027913665537370818788
0.56022332956424655356825
0.63023593114440356926982
0.71025163302459256817171
0.8002673352251266730
0.9002831374353476950
1.0002988393155357139
1.120274936185330
1.250280537035414
1.400288938155526
1.600300139555666

 

The actual version of the Transformer Standard IEC 61558-16 gives much lower values than IEC 60317-0-7 because

  • IEC 60317-0-7 uses the increase of insulation (Outer diameter - Bare wire diameter) for calculation while IEC 61558-2-16 uses the thickness of insulation (Outer diameter - Bare wire diameter)/2 as base, which results in half of the BDV-values of IEC 60317-0-7.
  • The specific voltage per micron is given acc. to IEC 60317-0-7 and IEC 61558 at 180 °C and acc. to IEC 60317-0-7 also at room temperature. Actually needed temperature of SMPS (Switch Mode Power Supply) is somewhere in between.
  • For calculation of BDV, IEC 60317-0-7 takes the average outer diameter, while IEC 61558 takes the maximum, which results in slightly higher values of IEC 61558.

 

These differences of BDV values should be clarified with the next revision of IEC 61558.