Type-tested low-voltage switchgear and controlgear assembly (TTA)

A low-voltage switchgear and controlgear assembly conforming to an established type or system without deviations likely to significantly influence the performance, from the typical ASSEMBLY verified to be in accordance with this standard. IEC 60439-1 / EN 60439-1;2.1.1.1.

Partially type-tested low-voltage switchgear and controlgear assembly (PTTA)

A low-voltage switchgear and controlgear assembly, containing both type-tested and non-type-tested arrangements provided that the latter are derived (e.g. by calculation) from type-tested arrangements, which have complied with the relevant tests. IEC 60439-1 / EN 60439-1; 2.1.1.2.