What this MCCB is and what it does
The Siemens SENTRON 3VA1132-4EF32-0BA0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection — the primary role is protecting cables and distribution bus against overloads and short circuits in a panel. It carries a TM240 thermal-magnetic trip unit, so the thermal element handles sustained overloads and the magnetic element clears fast faults. Rated 32 A continuous at 40 °C ambient, it holds that rating flat through 50 °C before starting a gentle derate: 31 A at 55 °C, 30 A at 70 °C. That means in a warm enclosure you lose only 2 A at the top of the operating range, which is better than many breakers that drop 10–15% by 50 °C. Breaking capacity is where this breaker earns its panel space: 121 kA at 240 V AC, 75.6 kA at 415 V, 52.5 kA at 440 V, and still 11.9 kA at 690 V. Those numbers tell you it's built for high-fault installations — think large transformer secondaries, busway feeds, or industrial distribution where the available fault current is well above 50 kA. The 800 V rated insulation voltage (Ui) confirms it's designed for 690 V systems with margin. It ships with an undervoltage release (UVR) built in — the designation means the UVR is part of the basic switch assembly, not a field-added accessory. That's a common requirement for safety circuits where the load must drop if control power fails. No ground-fault monitoring, no communication module, no trip indicator on the front face — this is a straightforward line-protection MCCB, not a metering or remote-trip variant.
Panel fit and dimensions
Footprint is 76.2 mm wide (3 in), 130 mm tall (5.12 in), 70 mm deep (2.76 in). The 70 mm depth clears most enclosures with room for wiring gutters.
What the ratings mean for coordination
The 121 kA at 240 V is the short-circuit capacity (Icu) — the maximum fault current this breaker can safely interrupt without welding contacts or rupturing the case. In a 480 V panel fed from a 150 kVA transformer, the available fault current at the main lug is typically 20–30 kA, so this breaker has 4x headroom. That matters for selective coordination: you can put a 32 A feeder breaker downstream of a larger main and trust the main won't trip on a downstream fault if the time-current curves are properly gapped. Power loss is 13.1 W maximum at rated current — negligible for thermal budgeting in a ventilated enclosure, but worth noting if you're packing six of these in a sealed stainless steel box. The operating temperature range is -25 °C to 70 °C, storage from -40 °C to 80 °C, so it handles cold warehouses and hot machine cabinets without issue.