Siemens SENTRON 3VA1220-4GF42-0CH0 — 200 A MCCB with High Interrupting Capacity
The Siemens SENTRON 3VA1220-4GF42-0CH0 is a 4-pole molded case circuit breaker rated at 200 A continuous, designed for line protection in distribution panels. Its interrupting capacity reaches 121 kA at 240 V AC and 75.6 kA at 415 V AC, which means it can safely clear high-fault currents in industrial mains without upstream coordination failure — a key spec for selectivity studies on large switchboards.
Breaking Capacity Across Voltages — Selectivity Headroom
At 440 V the breaker is rated for 52.5 kA, at 500 V for 17 kA, and at 690 V for 11.9 kA. These figures define the maximum fault current the breaker can interrupt at each voltage level; for a 415 V panel with a prospective short-circuit current of 50 kA, the 75.6 kA rating gives comfortable headroom above the 50 kA threshold, avoiding the need for current-limiting fuses upstream.
Thermal Derating — Continuous Current vs Ambient Temperature
The breaker carries its full 200 A rating up to 50 °C ambient. At 55 °C it derates to 194 A, at 60 °C to 188 A, at 65 °C to 182 A, and at 70 °C to 176 A. For a panel operating at 55 °C, the 194 A limit means a 200 A load would trip thermally; the BOM should either reduce the load or account for the 3 % derating.
Integration and Panel Fit
The breaker measures 140 mm wide, 158 mm high, and 70 mm deep. It mounts on a DIN rail or directly to a backplate via the molded case footprint. The 4-pole design occupies the same width as four single-pole MCCB modules, so a panel layout that allocates 140 mm per breaker row will accept this unit without re-spacing.
Built-in Auxiliaries and Releases
The breaker comes with 2 auxiliary switches plus 1 trip alarm switch (HQ type) and an undervoltage release (UVR). The UVR trips the breaker when supply voltage drops below a set threshold — useful for preventing automatic reclosure after a brownout. The auxiliary switches provide status feedback to a PLC or remote monitoring system.
Environmental and Electrical Ratings
Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. Insulation voltage is rated at 800 V. Maximum power loss at rated current is 44.5 W, which should be factored into enclosure thermal calculations.