Insulators for overhead lines with a nominal voltage above 1000 V. Insulator strings and insulator sets for a.c. systems. Definitions, test methods and acceptance criteria|Electric insulators, Overhead power-line fittings, Overhead power lines, Electric power transmission lines, Pin insulators, Railway electric traction equipment, Railway equipment, Railway fixed equipment, Electrical testing, High-voltage tests, High voltage, Impulse-voltage tests, Seatings, Glass, Ceramics Railway applications