The Siemens SENTRON 3VA9977-0KB00 is a position signaling switch accessory designed specifically for the plug-in and draw-out units of the 3VA molded-case circuit breaker family. It mounts directly onto the breaker's mechanism to indicate whether the breaker is in the connected, test, or disconnected position — a signal the control system needs for interlocking or status monitoring. The switch is 8.5 mm wide and 33 mm deep, sized to tuck alongside the breaker without expanding the panel footprint beyond the existing DIN-rail layout.
Switching capacity by voltage — what the ratings mean
Rated at 6 A for AC-12 duty (resistive loads) across 12 V to 230 V, and the same 6 A for DC-12 at 12 V. That DC rating drops to 3 A at 24 V, 1 A at 48 V, 0.5 A at 110 V, and 0.25 A at 230 V — standard derating for DC arcs. The thermal current limit Ith is 6 A, so the contacts are sized for continuous current at that level. For a control engineer, the practical takeaway: this switch handles typical 24 VDC PLC input signals (3 A) without issue, but if you need to switch a 48 VDC solenoid at 1.5 A, you're above the rating and need a relay interposer.
Voltage isolation and environment
That means it's suitable for fixed-installation panels in industrial environments where transient surges are common and conductive dust or humidity is present.