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Glass Covered Conductor

Glass Covered Conductor

Insulated glass covered wire is a practical approach to the problem of reliable high temperature magnet wire insulation. Glass fibre magnet wire is manufactured by applying a combination of glass fibres onto a bare or film coated conductor.

The glass fibres are then insulated with a suitable varnish and heated to bond the fibres to the conductor and to each other. This system produces an insulation of extreme toughness and abrasion resistance. Wilec manufactures single or double wraps of varnished glass over round and shaped conductors, bare or film insulated. Transwire varnished glass magnet wire is recommended for Class B, F or H equipment dependant on which type of insulation varnish is applied.Generally speaking glass insulated magnet wire can be used extensively in electrical machinery where high temperatures, vibration and excessive moisture conditions are encountered.

Description

Increase in Dimensions Due to the Covering

1 2 3 4 5 6 7 8
Larger dimension of conductor Minimum increase in dimensional over actual conductor dimensions Maximum increase in dimensions over maximum permissible conductor dimensions
Over Up to and including Grade 1 Grade 2 Grade 3 Grade 1 Grade 2 Grade 3
mm mm mm mm mm mm mm mm
3.55 0.18 0.25 0.35 0.23 0.33 0.43
3.55 5.60 0.25 0.35 0.33 0.43
5.60 0.35 0.43

NOTE: The maximum increase in dimensions may be amended when IEC Recommendation is published

1. Adhesion and Flexibility

1.1 As received. Samples of the glass-covered conductor shall be bent through 180° round a mandrel having a diameter 10 times the bare width of the conductor when it is bent on edge, or 10 times the bare thickness when it is on the flat. Separate samples shall be bent, one on edge and one on flat and when so tested the covering shall not open sufficiently to expose the bare conductor to view, when examined under diffused light by normal eyesight. There shall be no appreciable loosening of the insulation.

1.2 After heating. Samples which have been heated for 16 h in an oven at a temperature of 150°C to 155°C and then allowed to cool to room temperature, shall pass the test for flexibility and adherence specified in 1.1.

2. Breakdown voltage. The wire shall meet the requirement of 2.1 and 2.2. when tested at room temperature and at elevated temperature respectively.

2.1. Tests at room temperature. Samples shall be subjected to a breakdown voltage test by the method described in Appendix E. At least four of the five places tested shall not break down at a voltage less than the appropriate value in Table 4, and the fifth at a voltage not less than 50% of the required value.

2.2. Test at elevated temperature. When tested by the method described in Appendix E, at the rated temperature, at least four of the five samples tested shall not break down at a voltage less than the appropriate value in Table 4, and the fifth at a voltage not less than 50% of the required value.