Line protection MCCB with 121 kA interrupting capacity
The Siemens SENTRON 3VA1020-4ED32-0KH0 is a 3-pole molded case circuit breaker rated for line protection, carrying 20 A continuous at 40 °C through 50 °C before thermal derating begins. At 55 °C it holds 19.2 A, at 70 °C it holds 18 A — the TM210 thermal-magnetic release tracks ambient temperature inside the panel, so if the enclosure runs hot, factor the derate curve into your BOM current margin. Breaking capacity is 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at 690 V — that 121 kA figure at 240 V means it can safely clear a bolted fault on a high-capacity transformer secondary without the arc re-striking or the case rupturing. The 690 V rating drops to 11.9 kA, which still covers most industrial 690 V distribution panels with typical transformer impedances. Rated insulation voltage Ui is 800 V. The front carries IP40 protection.
Mounting and auxiliary configuration
Measures 76.2 mm wide, 130 mm tall, and 70 mm deep — a standard 3-pole MCCB footprint. It ships with 2 auxiliary switches plus 1 trip alarm switch (HQ configuration), and a shunt trip release (STL) is integrated — the shunt trip order code is 3VA9688-0BL33. No undervoltage release, no ground fault monitoring, no communication module, and no phase failure detection on this variant. If you need remote trip indication or a UVR, this is not the build; you would step to a different suffix. Mechanical endurance is rated at 15,000 operations.