The 125 A continuous rating (Iu) holds flat from 40 °C up to 50 °C, then derates gradually: 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C. Breaking capacity is what decides whether this breaker survives a fault or welds shut. At 240 V it's rated 220 kA — enough for high-fault utility feeds. At 415 V it's 154 kA, at 440 V it's 75.6 kA, and at 690 V it's 17 kA.
Thermal-magnetic release and auxiliary contacts
The overcurrent release is a TM240 — a fixed thermal-magnetic trip unit sized for 125 A frame. It ships with three HQ auxiliary switches (form C) for remote status feedback, so you can wire the breaker into a PLC or annunciator without adding a separate switch block.
The breaker measures 130 mm high, 76.2 mm wide, 70 mm deep — a standard 3-pole MCCB footprint for DIN-rail or panel-mount installation. Front protection is IP40 (tools and fingers stay out), and the operating temperature range is -25 °C to 70 °C, with storage from -40 °C to 80 °C. No trip indicator on the front, so status comes from the auxiliary contacts or a visual check of the handle position.