Litz Wire Test & Inspection Data

Please click each of the Taps below.

Breakdown Voltage Testing Method

The method of the pin hole test ( KSC 3006 )

AAA. Breakdown Voltage Testing of Litz Wire
– You must set the test with maximum allowable value of leakage current as 5mA, not 20mA.
– The copper wire not coated must be wrapped at intervals of 5cm for BDV(Break Down Voltage) test.

 

BBB. Breakdown Voltage Testing of Enamelled Copper Wire
– Name of product : Enamelled Copper Wire
– Name of test : Breakdown Voltage Measuring

# Test Methods & Conditions ( KSC 3006 PART 11 )
1) The metal cylinder method is used for copper wire 0.040mm less
2) The twisting methgod is used for copper wire 0.050mm or more.
– The breakdown voltage shall be measured by increasing voltage at the proportion of 500V/s at the same rate as much as possible you can. ( However, the speed of the induced voltage shall be reduced if it is breakdown within 5 seconds and then make it breakdown more than 5 seconds. )

1. The metal cylinder method
– Specimen, lengths of approx. 30cm from the same spool shall be taken for three, shown as the picture, each specimen shall be attached to the cramp. And the specimen diameter of approx. 25mm smooth surface of a cylinder is wound for a time at the end shown as Table 1, while applying for an indicated tensile force between the metal cylinder and a conductor, applying AC voltage close to a sine wave of 60Hz. In addition, the transformer capacity shall be more than 100VA.
[Data Table 1]

Conductor diameter Tension(gf)
0.25~0.025mm 2
0.03~0.040mm 5

 

[Picture]

 

2. The method of two twisted lines
– Specimen, lengths of approx. 50cm from the same spool shall be taken for three, Fold into two specimens of each together. Shown as Table 2, apply for tensile force and cut into approx. 12cm lengths. And apply for AC voltage close to a sine wave of 60Hz. In addition, the transformer capacity shall be more than 500VA.
[Data Table 2]

Conductor diameter(mm) Tensile force(g) No. of twist turns
0.02 ~ 0.025 2
0.03 ~ 0.04 5
0.05 3 50
0.06 ~ 0.07 5 40
0.08 ~ 0.11 10 30
0.12 ~ 0.17 40 24
0.18 ~ 0.29 120 20
0.30 ~ 0.45 350 16
0.50 ~ 0.70 450 12

 

[Minimum BDV(Breakdown Voltage) Specification as Item(Unit:kv)]

Division HUEW 0.03 HUEW 0.035 HUEW 0.04 HUEW 0.05
Grade 0 4 6
Grade 1 1.2 3 3
Grade 2 0.90 0.9 0.9 0.95

 

1. The metal cylinder method
a. mount the metal cylinder jig to the breakdown measuring instrument

 

b. hang the load (weight) on the specimen and mount it to the metal cylinder jig

 

c. measures the increased voltage

 

2. The method of two twisted lines
a. sampling

 

b. Table 2 in the sample loading jig hanging load up

 

c. Table 2 according to the number of twists and twisted removes the load

 

d. one end to the sample to be electrically energized to remove film

 

e. breakdown sample jig bite

 

f. measures the increased voltage

* Pin Hole Measuring Instrument

– class 0 : up to max. 3 pin holes
– class 1 : up to max. 5 pin holes
– class 2 : up to max. 8 pin holes
– class 3 : up to max. 12 pin holes

 

 

Testing method under KSC 3006
– Regarding the conductor diameter ( less than 0.06㎜ ), the conductor specimen length shall be Approx. 1.5m. Regarding the conductor diameter ( more than 0.07mm ), the conductor specimen length shall be Approx. 6m. The specimen is gone through the heat treatment in the constant temperature gears ( in case of the temperature of the absence of regulation : 125 ± 3 ℃) maintaining for about 10 minutes. After the heat treatment, the specimen is not pulled or bended and then it is dipped in 0.2% saline solution which 3% alcohol solution of phenolphthalein is moderately dropped. In 0.2% saline solution for conductor diameter less than 0.06㎜, the conductor length shall be about 1m. In 0.2% saline solution for conductor diameter more than 0.07m , the conductor length shall be about 5m. Liquid anode, the specimen conductor is set up cathodically and then when 12V DC is applied for about 1 minute, you are able to check out how many pinholes are occurred.
ex) The Pinhole Test Method and Sequence

1. Sampling

 

2. Removing the coating (using the fire) terminal at the end of the sample for electric current flowing.

 

3. And then connecting the end of the sample to the terminal.

 

4. Counting pinholes occured.

 

5. Check out whether the energized by using the other end of the sample.

ex) If it is unable to determine whether pinholes occur
– Check out phenolphthalein diluted 3% alcohol with 0.2% saline
– Check out both terminals’ (+, -) location