What is the Solid-Insulated Switchgear ?
Breaking capacity (short-circuit interruption): Usually 20kA, 25kA, or 31.5kA.
This eco-friendly technology uses solid dielectric material (e.g., epoxy resin) instead of SF₆ gas. All live parts are fully encapsulated, ensuring compact size, high safety, and low maintenance. Common applications include secondary distribution networks, wind power, and rail transit.
Introduction to Solid Insulated Switchgear
Solid insulated switchgear (SIS) is a medium-voltage electrical distribution device that uses solid dielectric materials—such as epoxy resin or polyurethane—as the primary insulation for live parts, instead of traditional SF6 gas or air. This technology is widely applied in ring main units, switchboards, and compact substations.
The key feature of SIS is its environmental friendliness. Since it contains no SF6 gas—a potent greenhouse gas—it has near-zero global warming potential. Its solid insulation structure makes the equipment maintenance-free, compact, and highly resistant to harsh environments such as humidity, salt fog, and dust, making it ideal for offshore, industrial, and high-altitude installations.
SIS typically includes load-break switches, vacuum circuit breakers, and fuses, all encapsulated within a grounded metal enclosure. Operation is often via a mechanical mechanism with visible isolation breaks, ensuring safety. Ratings commonly range from 12 kV to 40.5 kV, with current capacities up to 1250 A.
Compared to air-insulated and gas-insulated switchgear, solid insulated switchgear offers enhanced operational safety, lower lifecycle costs, and reduced environmental impact. However, challenges such as higher initial cost and insulation aging under long-term thermal cycling must be managed. Despite these, SIS is a growing choice for green, reliable, and compact power distribution solutions.
