SENTRON 3VA2125-5KP36-0AA0 — 25 A MCCB with ETU850 Trip Unit
The Siemens 3VA2125-5KP36-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for 25 A continuous current, with a 3-pole configuration and an ETU850 electronic trip unit. It's designed for line protection in distribution panels and switchgear, where the ETU850 provides adjustable overload and short-circuit protection curves — useful for coordinating with downstream breakers in a selective system. The breaking capacity reaches 187 kA at 240 V AC, dropping to 121 kA at 415/440 V, and 75.6 kA at 500 V; at 690 V it's still rated at 3.7 kA. That spread tells you this breaker is built for high-fault installations, not just residential mains.
What the Ratings Mean for Your Panel
The 25 A continuous rating is the breaker's nominal current — it's the load it carries without tripping under normal conditions. The ETU850 trip unit lets you set the overload pickup and short-time delay, so you can achieve selectivity with downstream breakers. The 187 kA interrupting rating at 240 V is the maximum fault current the breaker can safely clear at that voltage; at higher voltages the arc is harder to extinguish, hence the lower figures. For a 480 V panel, the 121 kA at 415/440 V is the relevant number — still very high, covering most industrial service-entrance faults. The IP40 front protection means the breaker face is dust-protected but not sealed against water; it's fine for indoor panel mounting.
Integration Notes
Dimensions are 105 mm wide, 181 mm high, and 86 mm deep — standard for a 3-pole SENTRON 3VA2 frame. It mounts on a DIN rail or can be screw-fixed to a backplate. The ETU850 supports communication, so you can integrate it into a monitoring system via the breaker's communication module slot. The power loss at rated current is only 0.6 W, so heat buildup in a dense panel is minimal.