Siemens 3WA1125-3AB02-0AA0 3WA 3-Pole 2500A 66kA 690V Fixed Type Air Circuit Breaker ETU300 LSI

The Siemens 3WA1125-3AB02-0AA0 is a fixed-mounted, horizontally connected 3-pole air circuit breaker in the 3WA series, rated at 2500 A with a breaking capacity of 50 kA at 690 V AC. It ships with the ETU300 LSI electronic trip unit and 2NO+2NC auxiliary contacts factory-fitted, making it suited for main distribution switchgear panels where high fault-current interruption at low-voltage network voltages up to 690 V is required.

Technical Specifications

Certifications & Standards

• IEC 60947-2
• IEC 62443-3-3

Applications & Use Cases

At 2500 A rated current and 50 kA breaking capacity at 690 V, the 3WA1125-3AB02-0AA0 is dimensioned for incomer and bus-coupler positions in low-voltage main distribution boards operating on 690 V industrial networks — common in heavy process industries, offshore platforms, and large marine installations where line voltages exceed the standard 400 V tier.

The ETU300 LSI trip unit provides three independently adjustable protection functions: long-time delay (L) for overload, short-time delay (S) for selective fault discrimination, and instantaneous (I) for direct short-circuit tripping. This allows downstream selectivity coordination without requiring a more complex trip unit. The factory-fitted 2NO+2NC auxiliary contacts feed directly into SCADA or PLC discrete inputs without additional wiring accessories.

Fixed mounting eliminates the draw-out rail and shutter mechanism, reducing panel depth and overall cubicle cost where the breaker does not need to be isolated under live-bus conditions. Horizontal busbar connection aligns with standard rear-connected busbar systems used in form 3b and form 4 switchgear assemblies. At 33.229 kg, panel structural calculations should account for this load when specifying door-mounted or top-mounted configurations.