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    1. Classification of compensation wires 1.1 Tolerance level, classification of use conditions The compensation wire is divided into two types according to the tolerance of the thermoelectric characteristics: the normal temperature and the normal temperature. 1.2 structural form 1.2.1 The core type of the compensation wire is divided into two types: single-strand core and multi-strand core . The number of core strands is listed in Table 2 . 1.2.2 insulation layer, sheath, shielding layer Generally, the insulating layer and the sheath of the compensation wire are made of polyvinyl chloride as the main material; the insulating layer of the heat-resistant compensation wire is made of polytetrafluoroethylene as the main material, and the sheath is made of polytetrafluoroethylene or alkali-free glass fiber ( The surface should be coated with silicone or polytetrafluoroethylene dispersion paint baking) as a host material. The shielding layer is woven with tinned copper wire or galvanized steel wire or wrapped with a composite aluminum ( copper ) tape. 2 , technical requirements 2.1 insulation layer, sheath and shielding layer 2.1.1 The thickness of the core insulation layer, the thickness of the sheath and the maximum outer diameter of the compensation wire shall comply with Table 4 . 2.1.2 insulation layer Generally, the surface of the insulating layer of the compensation wire should be flat, uniform in color, and free of mechanical damage; the thickness tolerance of the insulating layer is negative 10% of the nominal thickness, and the thickness of the thinnest part is not less than 90% of the nominal value minus 0.1 mm ; The insulation layer should be subjected to AC 50Hz , and the spark test with a voltage of 4000V does not break down. The running speed of the test machine should ensure that the voltage applied to the insulation layer at each point is not less than 0.1s . The thickness tolerance of the insulation layer for heat-resistant compensation wire is minus 20% of the nominal thickness , and the thickness at the thinnest part is not less than 90% of the nominal value minus 0.1 mm . The outer diameter of the insulated core allows partial enlargement, but the thick portion The outer diameter should not exceed the maximum outer diameter value. 2.1.3 sheath Where polyvinyl chloride or polytetrafluoroethylene is used as the sheath, the sheath shall be tightly wrapped on the insulating layer of the core, the insulation layer and the sheath shall not be adhered, the surface shall be flat and the color shall be uniform. The allowable deviation of the thickness of the sheath is minus 20% of the nominal thickness , and the thickness at the thinnest is not less than 80% of the nominal value . A sheath woven with glass wool shall have a weaving density of not less than 90% . 2.1.4 shielding layer The weaving density is not less than 80% , and the broken ends should be trimmed after being connected; the composite aluminum ( copper ) tape should be closely attached to the insulating layer and not easy to loose; the thickness of the shielding layer should not exceed 0.8mm . 2.2 insulation resistance When the ambient air temperature is 15-35 ° C and the relative humidity is not more than 80% , the insulation resistance between the cores of the compensation wires and between the core and the shield layer is not less than 5 MΩ per 10 m . 2.3 physical and mechanical properties The physical properties and aging properties of the insulation layer and sheath of the compensation wire are generally in accordance with Table 5 . 2.4 heat resistance The heat-resistant compensating wire shall be subjected to a heat resistance test of 220±5 °C for 24 hours, and immediately after the specimen is bent 180 degrees on a cylinder of 5 times its diameter, there shall be no crack on the surface, and the core and line of the compensation wire shall be compensated. The insulation resistance between the core and the shield is not less than 25 MΩ per meter . 2.5 moisture resistance The heat-resistant compensation wire shall withstand an ambient temperature of 40±2 °C and a relative humidity of 95±3% . After 24 hours of moisture resistance test, the insulation resistance between the core of the compensation wire and the wire core and the shielding layer shall not be less than 25 MΩ . 2.6 low temperature winding performance Generally, the compensation wire should be subjected to the low temperature winding test at -20 °C , and the insulation layer of the sample wound on the test bar should be visually observed without any crack. |
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