What it is and what it does
The Siemens SENTRON 3VA9988-0AB11 is a tripped signaling switch — an accessory that mounts inside a 3VA molded-case circuit breaker to give a remote electrical indication when the breaker has tripped on fault. It's rated for a thermal current of 10 A and carries switching ratings across AC-12, AC-15, DC-12, and DC-13 loads at voltages from 12 V up to 600 V, so it can drive a panel lamp, PLC input, or alarm relay directly without an interposing contactor. Pollution degree 3 and overvoltage category III mean it's rated for the industrial control panel environment — conductive dust and transient surges from the distribution side are within its design envelope.
Where it fits
This switch is designed as an accessory for the Siemens 3VA family of circuit breakers. It snaps into the breaker's accessory slot — no separate DIN-rail footprint, no extra panel wiring for the switch body itself. The 14 mm width and 30 mm depth stay inside the breaker envelope, so it doesn't eat panel space. Wiring terminates with a stripped length of 15 mm (0.6 in) per terminal.