The Siemens SENTRON 3VM1125-5GE42-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current of 25 A at 40 °C through 50 °C, derating to 23 A at 70 °C. Its TM220 thermal-magnetic release provides LI protection — thermal for overload, magnetic for short-circuit — with an adjustable instantaneous trip threshold up to 320 A. The interrupting ratings are the headline here: 187 kA at 240 V AC, 121 kA at 415 V AC, 76 kA at 440 V AC, and 17 kA at 500 V AC.
The 101.6 mm width (4 inches) is a standard 4-pole MCCB footprint — it occupies four 25 mm pole spaces on a DIN rail or bolts directly into a panel backplate.
Rated insulation voltage and DC capability
Rated insulation voltage Ui is 690 V AC, which defines the maximum voltage the breaker's insulation system can withstand continuously. For DC applications, the maximum rated operational voltage is 500 V DC — useful for battery banks or DC bus distribution. The overcurrent release is the TM220 type, a thermal-magnetic design with fixed thermal and adjustable magnetic settings; the magnetic pickup (li) is adjustable up to 320 A.
Ambient temperature derating curve
At 55 °C it derates to 24 A, holds at 24 A through 60 °C, then drops to 23 A at 65 °C and 70 °C. This is a gentle derating slope — the breaker loses only 2 A over a 30 °C rise — so it's suitable for moderately warm enclosures without oversizing. Maximum power loss is 9 W at rated current.