25 A MCCB with ground-fault summation and communication
The Siemens 3VA2125-5KQ32-0AA0 is a SENTRON molded case circuit breaker rated for 25 A continuous current on a 3-pole line protection design. Its interrupting capacity hits 187 kA at 240 V, 121 kA at 415 V, and 75.6 kA at 500 V — numbers that govern fault-clearing at the main distribution board or high-fault substation feeder. The breaker carries a ground-fault monitoring version using summation current formation on the L-conductor, meaning it detects leakage by summing phase currents rather than requiring a separate toroid. Communication function is built in, so it can report status or trip events to a higher-level control system without an add-on module.
Interrupting capacity across voltage levels
The 187 kA at 240 V is the headline figure — enough for most North American 240 V services with high available fault current. At 415 V the rating holds at 121 kA, and at 440 V it stays at 121 kA. At 500 V it drops to 75.6 kA, and at 690 V it falls to 3.7 kA. That steep roll-off at 690 V means this breaker is not a candidate for 690 V high-fault applications; for those, step up to a higher-rated 3VA frame. The 25 A continuous rating is flat across the ambient range from 40 °C to 70 °C — no derating needed in a warm enclosure.
Integration dimensions and panel fit
At 86 mm deep, 105 mm wide, and 181 mm tall, the 3VA2125-5KQ32-0AA0 fits standard 3-pole MCCB panel cutouts. The 105 mm width is the same as the 3VA1 frame, so it drops into a panel laid out for the smaller 3VA1110-5ED32-0AA0 without rewiring the bus bars or drilling new mounting holes. Depth of 86 mm leaves clearance for a standard 200 mm deep enclosure with wiring gutters. The 3-pole design accepts up to 300 A maximum frame rating and down to 38 A minimum, though this specific unit is set for 25 A.
Environmental and electrical ratings
Operating temperature range spans -25 °C to 70 °C; storage range is -40 °C to 80 °C. The insulation voltage is rated at 800 V, giving headroom for 690 V systems even though the interrupting capacity at that voltage is limited. Power loss at rated current is 0.6 W maximum — negligible for thermal budgeting in a sealed enclosure. No undervoltage release or trip indicator is built into this order code, so if those features are needed, specify a different suffix.