Siemens SENTRON 3VM1332-4GE42-0AA0 — 320 A, 4-Pole MCCB with TM220 Trip Unit
The Siemens SENTRON 3VM1332-4GE42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection, carrying 320 A continuously at 40 °C through 50 °C ambient, then derating to 292 A at 70 °C. Its TM220 thermal-magnetic trip unit provides LI protection — fixed thermal overload plus adjustable short-circuit pickup up to 3,200 A. Breaking capacity reaches 121 kA at 240 V AC, 76 kA at 415/440 V, and 53 kA at 500 V, giving it strong fault-clearing headroom for industrial distribution panels.
Current Ratings and Thermal Derating
The breaker holds 320 A from 40 °C to 50 °C without derating. Above that, it steps down: 313 A at 55 °C, 306 A at 60 °C, 299 A at 65 °C, and 292 A at 70 °C. For a panel with internal temperature rise, the 70 °C figure is the one to size against — the breaker's own 80 W maximum power loss contributes to that heat. Operating ambient range is -25 °C to +70 °C; storage range is -40 °C to +80 °C.
Breaking Capacity and Voltage Ratings
Rated insulation voltage Ui is 690 V AC. Maximum rated operational voltage on DC is 500 V. The interrupting ratings cover common industrial supply voltages: 121 kA at 240 V AC, 76 kA at 415 V and 440 V AC, and 53 kA at 500 V AC. These figures support selective coordination downstream — the high 240 V rating is useful for large step-down transformer secondaries in North American panels.
Trip Unit and Protection Functions
The TM220 overcurrent release provides LI protection: fixed thermal overload (L) and adjustable instantaneous short-circuit (I) pickup, settable up to 3,200 A. No ground-fault monitoring is built in. No communication function or motor drive option is available on this version. The breaker is designed for line protection — it does not include a neutral conductor upgrade path.
Physical Integration and Environment
Dimensions are 248 mm high, 184 mm wide, 110 mm deep. Front-face protection is IP40 — suitable for enclosed panel mounting where tools or fingers may approach but not for washdown. The 4-pole footprint matches standard Siemens SENTRON MCCB cutouts; verify the mounting pattern against your existing panel drill plan before ordering.