EOW March 2014

Technical article

4 Test Results 4.1 Hot-set Test

Test

Required

Developed wire

INSULATION Hot-set test at 200º for 15 min Under load of 20N/cm 2 (%) JACKET Hot-set test at 200º for 15 min Under load of 20N/cm 2 (%) After unloading (%)

The results of the hot-set test are shown in Table 1 . Judging from the table, it was verified that this cable has excellent high temperature heat resistance without the use of electron beam irradiation. 4.2 Heat Deterioration Properties Table 2 shows a temperature at which an elongation residue percentage reaches 50 per cent after 20,000 hours of deterioration as determined by Arrhenius curves. Judging from the table, it was verified that this cable has excellent heat deterioration properties. 4.3 Single Vertical Combustion Test The results of the single vertical combustion test are shown in Table 3 . Judging from the table, it was verified that this cable has excellent incombustibility because the spread of fire did not occur in the upward and downward directions. 4.4 Other Characteristics Other characteristics of the newly developed cable are introduced below. Figure 1 shows the results of evaluating the end-strip workability of this cable. These results represent the observations of processed portions after stripping insulators by using a general insulation stripper. is structured of two layers: insulation and sheath. Any moustache-shaped burrs were almost not observed even after the two layers were processed at the same time. It was verified that these two layers had been stripped without problems. In addition, the results of evaluating the bleed characteristics of this cable are shown in Figure 2 . This newly developed product

100>

30

25>

3

<100

29

After unloading (%)

<25

4

▲ ▲ Table 1 : Hot-set test

Test

Required

Developed wire

INSULATION

>120

121.2

JACKET

>120

121.9

▲ ▲ Table 2 : Thermal endurance properties

Test

Required

Developed wire

An elongation percentage was measured 15 minutes later. After that, the load was removed. After the temperature of the oven was restored, the test pieces were removed and cooled down to room temperature. An elongation percentage was measured again. Test results are judged as acceptable if an elongation percentage under load is lower than 100 per cent and if an elongation percentage after the removal of load is 25 per cent. 3.2 Heat Deterioration Properties An insulating tube-shaped piece and a sheath tube-shaped piece were cut out from a cable. The time when an elongation residue percentage had reached 50 per cent at each deterioration temperature of 180ºC, 158ºC and 136ºC was verified. Judging from the Arrhenius curves of these three standards, the temperature at which an elongation residue percentage after 20,000 hours of deterioration had reached 50 per cent was verified. Test results are judged as acceptable if the above-mentioned temperature is higher than 120ºC. 3.3 Single Vertical Combustion Test A single vertical combustion test was performed in conformance to the IEC60332-1-2 standards. A 60mm sample was burned with a specified burner so that the lower part of the sample was CABLE Vertical flame spread resistance Length from top of cable to point of ending carbonisation (mm) Length from top of cable to point of starting carbonisation (mm) ▲ ▲ Table 3 : Single vertical combustion test

>50

370

<540

510

ignited for 60 seconds. After the flame was detached, the sample was left unattended until the flame was extinguished by itself. After the extinguishing was completed, the upper edge of a carbonised length was measured from the upper part of the sample, and the lower edge of a carbonised length was measured from the upper part of the sample. Each carbonised length is judged as acceptable if it is longer than 50mm or shorter than 540mm, respectively.

▼ ▼ Figure 1 : End strip workability

Developed wire

192

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March 2014