SENTRON 3VA2 — 500 A Motor Protection MCCB with Undervoltage Release
The Siemens 3VA2450-5MN32-0DA0 is a SENTRON 3VA2 molded case circuit breaker (MCCB) purpose-built for motor protection, carrying a 500 A rated current at 40 °C ambient and a 121 kA interrupting capacity at 415 V AC — enough to handle high-fault utility feeds downstream of a transformer without cascading upstream gear. The 3-pole design includes an integrated undervoltage release (UVR) that drops the breaker when supply voltage falls below a set threshold, which is standard for motor starter isolation where you need automatic disconnect on brownout or phase loss.
Breaking Capacity — Where It Holds and Where It Doesn't
The interrupting curve on this 3VA2 frame is worth a close read: 187 kA at 240 V AC, 121 kA at both 415 V and 440 V, then it drops to 75.6 kA at 500 V and only 9 kA at 690 V. For a 500 A motor protection breaker, the 415 V / 121 kA rating is the one that matters for most European and Asian industrial panels — it covers high-fault scenarios behind a 2 MVA transformer. The 690 V figure (9 kA) is a reminder this is not a 690 V main breaker; it's a feeder or motor branch device sized for 400 V class systems. The short-time withstand (6 kA limited to 1 s) is the coordination window for downstream selectivity.
Thermal Derating — Full 500 A Up to 50 °C
The 3VA2450-5MN32-0DA0 holds its full 500 A rating from 40 °C through 50 °C ambient — no derating needed in a typical ventilated enclosure. Above that, it steps down: 495 A at 55 °C, 490 A at 60 °C, 485 A at 65 °C, and 480 A at 70 °C. The operating range spans -25 °C to +70 °C, with storage from -40 °C to +80 °C. That 480 A floor at 70 °C still covers a 450 A motor FLA with headroom, so you're not forced to oversize the frame for a warm panel. Maximum power loss is 101.5 W — plan for that heat rejection in a sealed cabinet.
Physical Fit — Panel and Footprint
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That 138 mm width is a standard 3-pole MCCB footprint for this frame size — it drops into a 3VA2 fixed or plug-in base without panel modification. No auxiliary switch fitted as standard (the design of the auxiliary switch is 'without'), so if you need remote status, plan for a separate auxiliary switch block on the side. The undervoltage release is wired separately from the main power path; verify coil voltage rating against your control supply before commissioning.