IEC 60851-5:2011 pdf – Winding wires -Test methods -Part 5: Electrical properties
IEC 60851-5:2011 pdf – Winding wires -Test methods -Part 5: Electrical properties.
6.3.1 Specimen for a metal bath electrode
A straight piece of wire shall be bent into a U.shape to be lowered Into the metal bath according to Figure 9.
6.3.2 Specimen for a conductive suspension electrode
220.127.116.11 Enamelled round wire with a nominal conductor diameter up to and Including
A straight piece of wire (100 ± 5) mm in length shall be wound around a straight piece of bare copper wire of 1 mm to 2 mm diameter and subsequently coated with a conductive suspension, for example by brushing a layer of an aqueous graphite dispersion on the specimen, which shall then be dried, for example, for 30 mm at 100 C in an oven with forced air circulation.
18.104.22.168 Enamelled round wire with a nominal conductor diameter over 0,100 mm and enamelled rectangular wire
A straight piece of wire about 150 mm in length shall be coated with a conductive suspension,
for example, by brushing a layer of an aqueous graphite dispersion on the wire. The length of
this layer shall be (100 ± 5) mm. The specimen shall be dried, for example, for 30 mm at
100 °C in an oven with forced air circulation.
Test method A: The specimen according to 6.3.1 shall be lowered into the metal bath according to Figure 9.
Test method B: The specimen according to 6.3.2 shall be placed between the two metal blocks- The specimen shall be connected to the impedance meter and shall be allowed to reach the specified test temperature. Thereafter, the dielectric dissipation factor shall be read directly from the impedance meter.
One specimen shall be tested. The dielectric dissipation factor, the test frequency and the test temperature shall be reported.
7 Test 23: PIn hole test
The intent of this test is to find insulation defects after treatment with a salt water solution. The objective of this test is similar to that of the high-voltage continuity test in 5.3.
A wire specimen approximately 1,5 m in length is taken for conductors of nominal diameter less than 0.07 mm. and approximately 6 m In length for conductors of nominal diameter equal to 0.07 mm or more.
For a nominal diameter less than 0,07 mm. I m ± 0,05 m of wire shall be wound in a round shape with a diameter of 100 mm ! 50 mm.
For a nominal diameter of 0,07 mm or more, 5 m ± 0,2 m of wire shall be wound in a round shape with a diameter of 300 mm ± 100 mm.
The specimen is placed in an air circulation oven at 125 °C ± 3 C for 10 mm (see note 1 below) (if not otherwise specified In the relevant specification).
A.1 Tangent delta — Intersection point
A number of methods are available in order to check the repeatability of curing, These are included as examples.
The principle Is as follows: A specimen of enamelled wire Is treated as a capacitor, using the conductor as one electrode and as the other electrode either a coating of dried film of graphite, or a bath of molten metal. The temperature of the specimen is raised at a controlled and uniform rate and the dissipation factor ( is determined and plotted to produce a graph of dissipation factor tangent delta) vs. temperature. Interpretation of the curve allows a value of temperature to be obtained which relates directly to the degree of cure of the enamel film. Alternative methods are in use. in which the specimen is cooled from a higher to a lower temperature
A.2 Test methods
A.2.1 Method A
A.2.1.1 Using molten metal alloy with increasing temperature
An electronic bridge allowing the value of d to be determined directly shall be used.
Enamelled wire specimen shall be wiped clean with soft cloth and assembled onto the fixture. The wire specimen with fixture shall be immersed in a molten liquid metal bath pre-adjusted at the lowest temperature. The specimen shall be connected to the bridge with the conductor as the one electrode and the molten liquid metal as the other. The temperature of the assembly shall be increased at a steady rate from ambient temperature to a temperature to give a clearly defined curve. Readings of tangent delta and temperature are taken regularly and the results are plotted in a graph with linear axis for temperature and logarithmic or linear axis for tangent delta. Because the readings can vary quickly. it is preferable to take the readings automatically onto a chart recorder or computer system. The use of automatic recording allows the test to be performed with a more rapid temperature rise although great care should be taken to ensure that there is no significant lag between the reading and the actual temperature The actual equipment, temperature rise and Interpretation should be agreed between customer and supplier.