3-pole 50 A MCCB with 121 kA interrupting rating
The Siemens SENTRON 3VA1050-4ED36-0HH0 is a 3-pole molded case circuit breaker rated for 50 A continuous current (Iu) with a TM210 thermal-magnetic overcurrent release. Its interrupting capacity hits 121 kA at 240 V AC, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V — meaning it clears high-fault currents on the secondary side of a distribution transformer without upstream coordination headaches. The 800 V rated insulation voltage (Ui) covers 480Y/277 V and 600 V industrial panels comfortably. This is a line-protection variant (not motor-protection), so the TM210 release curve is sized for cable and busbar protection in distribution panels. The shunt trip (STL) design of the auxiliary release allows remote tripping via a control signal — useful for emergency-stop circuits or load-shedding schemes. There is no undervoltage release, no communication module, and no phase-failure detection; this is a straightforward thermal-magnetic breaker for fixed-distribution duty. The auxiliary contact configuration ships as 2 auxiliary switches plus 1 trip alarm switch (HQ variant), giving three dry contacts for status feedback to a PLC or annunciator panel. The integrated auxiliary trip accessory is order code 3VA9688-0BL30.
Thermal derating and panel integration
Rated continuous current holds at 50 A from 40 °C through 50 °C ambient, then derates to 48 A at 55 °C, 47 A at 60 °C, 46 A at 65 °C, and 45 A at 70 °C. In a sealed panel with multiple breakers ganged, account for the 70 °C operating maximum — the derating curve is gentle enough that a 50 A feeder in a 60 °C enclosure still carries 47 A, but the 45 A floor at 70 °C is the hard limit. Dimensions are 76.2 mm wide (roughly 3 inches — standard 3-pole MCCB footprint on a DIN rail or panel-mount adapter), 130 mm tall, and 70 mm deep. Front protection is IP40, so the breaker is splash-safe on the operator face but not sealed for washdown. Storage range spans -40 °C to 80 °C; operating range is -25 °C to 70 °C. Mechanical endurance is rated at 15 000 operations — typical for a distribution MCCB that sees infrequent switching (panel isolation, not motor starting). The trip indicator and voltage-trigger function are present, giving visual and electrical trip status.