Disc porcelain insulator (also commonly written as butterfly porcelain insulator) is an insulation and support component mainly used in low-voltage overhead distribution lines. Its name comes from its appearance, as it has two larger umbrella skirts resembling butterflies.

Its main uses can be summarized into the following two core aspects:

1. Support and fix wires

Binding and fixing wires: This is the core mechanical function of disc-shaped porcelain insulators. It firmly fixes the low-voltage wires using binding wires through grooves on its own structure. It needs to withstand mechanical loads such as the weight of the wire itself and wind force.

Connection fittings: Metal accessories (usually referred to as iron caps and iron feet) at both ends of insulators are used to connect with the cross arm and wire fixing fittings of the line.

2. Implement electrical insulation

Isolation voltage: This is its most basic electrical function. Disc type porcelain insulators can effectively isolate the voltage between live low-voltage conductors and grounded metal towers, prevent current leakage, and ensure the safety of the transmission line.

Increase creepage distance: Its butterfly shaped double umbrella skirt design can effectively increase the "creepage distance" (i.e. the length of the path that current needs to pass from the wire to the tower), improve insulation capacity, especially in humid or slightly polluted environments.

In summary, disc-shaped porcelain insulators are a common insulation component in low-voltage overhead distribution lines, which can reliably fix wires and provide necessary electrical insulation.