Four poles (3P+N) with neutral conductor switching, so it isolates all conductors on a three-phase plus neutral circuit. The 40 A rating is valid at 35 °C ambient; the datasheet provides a derating curve — 38.4 A at 40 °C, 37.6 A at 45 °C, 36.76 A at 50 °C, 35.92 A at 55 °C.
Occupies 4 modular width units (72 mm wide, 90 mm tall, 76 mm deep, 70 mm installation depth). Any mounting position accepted. Combined terminal top and bottom — line and load can enter from either side, which simplifies busbar routing in a distribution board. Sealable, so the panel builder can lock the toggle position after commissioning. IP20 with connected conductors — protected against finger contact, not against water ingress. Install inside a panel or enclosure that provides the environmental seal. Halogen-free and silicon-free construction, which matters for outgassing-sensitive environments like clean rooms or electronics assembly.
The 5SY6640-6 is an active catalog line within the Siemens SENTRON family.