The Nova 2018 Windability Tester performs a unique toughness test on magnet wire.
During the test, the insulation and conductor are subjected to various stresses such as;
- Elongation
- Friction
- Abrasion
- Adhesion
- Flexibility
- Heat, etc.
The following insulation failures can occur;
- Cracks (over cure of enamel)
- Abrasion failure (from under cure enamel)
- Adhesion / Flexibility Failure
- Enlarged pinholes (stretching of enamel from elongation)
- Heat (due to friction), etc.
In the presence of high voltage, the fault detection circuit detects these faults.
Test Principle:
The magnet wire is anchored between two directional wire mounting clamps under tension. The wire between
the two clamps is then passed through the mandrel/high voltage guide sheaves assembly. The wire is then
wrapped once around the mandrel. The mandrel is located between two sets of high voltage guide sheaves.
When the test starts, the mandrel/high voltage guide sheaves assembly moves from one end of the tester to the
opposite end repeatedly until the magnet wire fails. The wire being wrapped around the mandrel is elongated,
resulting in the reduction of the cross section (diameter) of the wire.
When 3 faults are detected, the numbers of stroke are counted. Low strokes count indicates the enamel is
under-cured or over-cured, presence of pinholes, low toughness, etc. High strokes count indicates that the
insulation is correctly cured with good toughness, abrasion resistance, flexibility, lubricity and adhesion.