... ranged between-40'c and +40'c, substitute pin-type insulators, insulate and fix the conductor wires and imporove the level ... American national standard adopted is ANSIC29.7 Wet-Process Porcelain Insulators-High-Voltage Line-Post Type, that is , 57 series products ... GB/T21206-2007 Characteristics of High-Voltage Line Post Type Insulators, that is PS or R series products. Disc Suspension Insulators