The Siemens 5SJ6340-6RC is a 3-pole miniature circuit breaker (MCB) from the Retail line, rated at 40 A with a B tripping characteristic and a 6 kA breaking capacity.
The B-curve characteristic means the magnetic trip operates between 3 and 5 times rated current (120–200 A for this 40 A unit), making it suitable for resistive or general-purpose loads with low inrush — think lighting banks, heating elements, or small control transformers. The 6 kA breaking capacity at 400/415 V covers the fault current available at most downstream sub-distribution boards in a standard commercial installation.