Medium-Voltage insulators up to 36kV for indoor use

Construction

Indoor post insulators of aromatic cast resin are cyclindrical solid insulators.The main dimensions are in accordance with IEC 60273 – 1990. Three fixing bushes are cast into the insulator top. The metal head fittings are electrically connected. One fixing bush is cast into the center of the insulators foot.

Tests

The following tests to IEC 60660 – 1999 are performed:
Type tests

• Test with rated power-frequency withstand voltage (dry).
• Test with rated lightning impulse withstand voltage.
• Testing of minimum failing loads (nominal loads) for: Bending, tension, torsion.

Sample tests

• Testing of minimum failing load for: Bending

Routine tests

• Visual inspection.
• Testing of conductive connection of threaded fixing bushes.

For post insulators type B (IEC 60660 1999):

• Test with rated power-frequency withstand voltage (dry).
• Partial discharge extinction voltage test.