An insulator string is a component consisting of two or more insulator elements combined to flexibly suspend a wire. Insulator strings are protective devices with fixed and operational requirements for hanging wires and insulating wires from towers and earth.
Suspension insulator string is suitable for single suspension insulator string in straight line tower (or jumper wire of tension-resistant tower). In normal operation, it can only bear the conductor and additional vertical load and wind load, and also bear the wire breaking tension of the conductor in case of an accident. So the dangling insulator string has to satisfy both of these conditions. Due to the different vertical loads, the pendant insulator strings in each phase may be assembled in different types of single string, double string or multiple strings.