The 3VA1120-5MH36-0AA0: The interrupting ratings tell the real story: 187 kA at 240 V AC, 121 kA at 415 V, 75.6 kA at 440 V, and 7.5 kA at both 500 V and 690 V. That 187 kA at 240 V means it can clear a bolted fault on a large transformer secondary without the breaker failing — a high-fault-duty panel spec, not a branch-circuit number. At 690 V the 7.5 kA still covers most motor-starting fault scenarios in 690 V distribution. Current rating holds flat 20 A from 40 °C through 55 °C, then derates to 19 A at 60–70 °C. That means in a warm panel with ambient hitting 55 °C, you still get full 20 A — no early derating penalty. The TM120M release is a standard thermal-magnetic curve, not electronic, so no auxiliary power needed for the trip unit.
Panel Fit and Integration
Footprint: 76.2 mm wide (3 in), 130 mm tall, 70 mm deep. That 70 mm depth is the body depth behind the panel face — important for shallow enclosure clearance. IP40 on the front means it's protected against tools and wires >1 mm, but not against water ingress; keep it inside a rated enclosure. No undervoltage release, no shunt trip, no communication module on this variant — it's a straight thermal-magnetic breaker with no add-on accessories fitted. Rated insulation voltage Ui is 800 V, and operating voltage max is 690 V AC. That 800 V insulation rating means it's suitable for 690 V line-to-line systems with margin — no need to oversize for voltage stress. Power loss max is 12 W; in a dense panel with multiple breakers, that heat adds up, so leave breathing space around the unit.