These circuit breakers are available as individual free-standing units to form either single or multi-panel switchboards, with single or double isolation chambers, or are suitable for transformer mounting to form a complete substation, depending on the desired application. The Brush range of dry type flameproof transformers are available with ratings up to 3500kVA, 12kV, and use class '220' insulation as standard, which possess superior thermal stability, are highly resistant to moisture and are impervious to deterioration by ageing.