Siemens 3VA1225-6EF32-0HH0 — 250 A MCCB with line protection and shunt trip
The Siemens 3VA1225-6EF32-0HH0 is a SENTRON molded case circuit breaker (MCCB) rated for 250 A at 40 °C, with a 3-pole configuration and a breaking capacity of 220 kA at 240 V. Designed for line protection, it integrates a shunt trip (STL) release and comes with 2 auxiliary switches plus 1 trip alarm switch HQ. The 800 V rated insulation voltage supports 400 V and 690 V distribution systems common in industrial panels. At 57 W maximum power loss, this MCCB runs cool enough for high-density DIN-rail or panel-mount layouts where heat buildup from multiple breakers can derate adjacent components. The 70 mm depth (2.76 in) and 105 mm width (4.13 in) fit standard Siemens 3VA mounting footprints — no panel rework needed when swapping from an earlier 3VA frame.
Breaking capacity and thermal derating — what the ratings mean
The 220 kA at 240 V is the maximum prospective fault current this breaker can safely interrupt at that voltage level — critical for high-fault locations like transformer secondaries or large motor control centers. At 415 V the rating drops to 154 kA, at 440 V to 75.6 kA, at 500 V to 30 kA, and at 690 V to 17 kA. These values govern selectivity coordination downstream: a 220 kA SCCR at 240 V means the breaker clears faults up to that threshold without upstream devices needing to trip. Thermal derating is flat at 250 A from 40 °C through 50 °C, then steps down: 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. For a panel running at 60 °C ambient — common in sealed enclosures with multiple breakers — the usable continuous current is 237 A, not 250 A. Plan the load at the derated figure, not the 40 °C nameplate.
Integration — panel fit and auxiliary wiring
Mounts on a DIN rail or direct-panel via the 3VA base plate. The 105 mm width occupies three 35 mm DIN spaces (3 x 35 mm = 105 mm) — standard for a 3-pole MCCB this frame size. Depth of 70 mm leaves clearance for rear-access busbars and cable glands on a 200 mm deep enclosure. Auxiliary switch configuration is 2 auxiliary switches + 1 trip alarm switch HQ. The shunt trip (STL) release is factory-fitted; no field kit needed. The supplied basic switch variant is 3VA12256EF320AA0 — verify the trip indicator (present) and undervoltage release (absent) match your safety circuit design. Communication function is not built in; this is a standalone thermal-magnetic breaker.