Line protection MCCB with 187 kA interrupting capacity at 240 V
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. That 187 kA figure at 240 V means this breaker can safely clear a fault current up to 187,000 A without rupturing or welding its contacts — a spec that matters when the available fault current at the panel is high, such as near a large transformer or in a high-capacity distribution board.
Panel fit and mounting dimensions
The breaker measures 101.6 mm wide, 130 mm high, and 70 mm deep. 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. The 70 mm depth means it clears most standard gland plates and enclosure doors without interference. Front face carries an IP40 protection rating, so it's protected against tools and wires >1 mm but not sealed against moisture; install in a dry enclosure or add a cover for washdown areas.
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. No ground-fault monitoring, no motor drive, no communication function on this variant — it's a straight line-protection breaker.
Ambient temperature derating curve
The continuous current rating holds at 25 A from 40 °C through 50 °C. 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. Storage temperature range is -40 °C to 80 °C; operating ambient is -25 °C to 70 °C. Maximum power loss is 9 W at rated current.