The Siemens 5SU1644-7RC40 is a 4-pole RCBO (residual current circuit breaker with overcurrent protection) rated at 40 A, occupying 7 module spaces on the DIN rail. The C characteristic trips between 5 and 10 times rated current, covering motor-start and moderate inrush loads. Type A residual current detection handles pulsating DC and sinusoidal AC fault currents up to 300 mA, which covers most single-phase electronic loads like switched-mode power supplies and variable-speed drives.
The 7-module width (roughly 126 mm on a standard DIN rail) fits into a distribution board or sub-panel with room for adjacent breakers or contactors. The C-curve characteristic suits circuits with motor loads, pumps, or compressors where the inrush current exceeds the B-curve threshold but stays within the C-curve range.