Motor protection MCCB with ETU350M trip unit
The Siemens 3VA2325-5MN32-0DC0 is a SENTRON 3VA2 molded case circuit breaker (MCCB) configured for motor protection, with a 250 A rated continuous current (Iu) and an ETU350M electronic overcurrent release. The 3-pole design and 250 A frame mean this breaker handles the full-load current of a motor sized around that rating, with the ETU350M providing adjustable thermal-magnetic or electronic protection curves for motor starting inrush and overload. The interrupting capacity reaches 187 kA at 240 V, 121 kA at 415 V, and 75.6 kA at 500 V — figures that give substantial fault-clearing headroom in most industrial distribution panels without needing upstream current-limiting fuses. This is a motor-protection variant, meaning the trip unit is tailored for motor branch circuits — it handles the high inrush on start and provides overload protection matched to motor thermal damage curves, not just cable protection. The ETU350M is a microprocessor-based unit with adjustable settings for long-time pickup, short-time pickup, instantaneous, and ground-fault (though this specific order code ships without ground-fault monitoring). Phase failure detection is built in, which is critical for three-phase motor loads where a lost phase can single-phase and burn the winding.
Panel fit and thermal derating
The breaker measures 138 mm wide by 248 mm high by 110 mm deep. That 110 mm depth is the dimension that matters most when fitting into an existing enclosure — it's the projection from the mounting surface. The 138 mm width is the pole-pitch footprint; three poles at roughly 46 mm per pole is standard for this frame size. Mounting is via the rear panel or DIN rail adapter (not specified here but typical for the 3VA2 platform). Thermal derating is published: the breaker carries the full 250 A continuously up to 50 °C ambient. At 55 °C it derates to 240 A, at 60 °C to 235 A, at 65 °C to 230 A, and at 70 °C to 225 A. For a panel with multiple breakers ganged together, the internal temperature rise will be higher than the room ambient — use the 50 °C column as the practical limit unless you have forced ventilation. Maximum power loss is 40 W.
Auxiliary releases and switching capacity
This order code includes an undervoltage release (UVR) as the auxiliary release — the UVR trips the breaker when control voltage drops below a threshold, which is standard for safety circuits that need to drop power on loss of control supply. The integrated auxiliary trip is order code 3VA9608-0BB25. The breaker ships with 2 auxiliary switches, HQ (high-quality) type, for remote status indication. Mechanical endurance is rated at 15,000 operations — that's the latching mechanism life, not the electrical contact life under load; electrical endurance will be lower and depends on the switched current. No communication function is fitted on this variant — no Modbus, PROFIBUS, or Ethernet interface. If you need remote monitoring of trip status and load current, you would add the communication module separately or choose a different 3VA2 variant with the ETU350M and a comms option. The basic switch supplied as the core is order code 3VA2325-5MN32-0AA0.