Line protection MCCB with full-temperature rating
The Siemens 3VA2140-7HK42-0AA0 is a SENTRON molded case circuit breaker rated for line protection, 4-pole, with a continuous current Iu of 40 A that holds flat across the entire operating range — 40 A at 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, and 70 °C. That means no derating curve to chase in a warm panel; the 40 A rating is good right up to the maximum ambient of 70 °C. Breaking capacity is specified per voltage: 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 53 kA at 690 V. At 415 V, the 242 kA figure covers most industrial distribution panels with high fault current — no need for current-limiting fuses upstream for typical installations within that range.
ETU340 release and selectivity
The overcurrent release is an ETU340, a microprocessor-based unit with adjustable N-conductor protection (OFF or 100%) and a fixed time delay tr of 1300 ms. The fixed tr simplifies coordination — you know the long-time delay is 1.3 s, no guesswork on the curve. The 20 000 electrical endurance cycles (latching) suit it for frequent switching applications like main incomers or feeder breakers in production lines.