Three poles, rated for a maximum of 320 A, with a TM120M thermal-magnetic overcurrent release.
Breaking capacity — what it interrupts and where
Rated breaking capacity varies sharply with system voltage. At 240 V it clears 187 kA — enough for most low-voltage industrial services. That last number matters: on a 480/500 V system (common in North American and some Asian plants), the available fault current has to be coordinated with this 17 kA ceiling, or the breaker won't interrupt a high-energy fault safely. Insulation voltage is rated at 800 V, so the internal clearances are there for 690 V class systems — the limitation is the arc extinction at higher voltages, not the dielectric.
Thermal derating — continuous current vs panel temperature
Continuous current rating holds at 20 A from 40 °C through 55 °C ambient. At 60 °C it drops to 19 A, and it stays at 19 A through 70 °C.
What it doesn't have — and why that matters for your panel
This is a bare electromechanical MCCB — if you need remote signaling or a shunt trip for emergency-off circuits, you'll add external accessories or pick a different variant. The 3-pole form factor fits standard SENTRON panel-mounting footprints; dimensions are 70 mm deep, 76.2 mm wide, 130 mm high. Width is exactly 3 inches — matches the standard MCCB cell width in most distribution boards.