What it is and where it fits
The Siemens SENTRON 3VM9988-0AA13 is a 7 mm wide auxiliary switch — a changeover contact block that snaps into the accessory slot on 3VM and 3VA molded-case circuit breakers. It signals breaker state (open/closed/tripped) back to a PLC or status lamp without tapping the main power path. At 30 mm deep and 56 mm tall, it tucks into the breaker profile without protruding past the DIN-rail edge — no extra panel depth needed beyond what the breaker already occupies.
Switching capacity — what the ratings mean for your circuit
Rated 0.3 A in AC-15 duty at 24 V — AC-15 covers solenoid and electromagnetic loads, so this switch handles control relays and contactor coils typical in a panel. At DC-13 (solenoid with parallel diode suppression), the rating drops to 0.07 A at 24 V; the inductive DC break is harder on the contacts, so respect that lower limit for DC pilot circuits. The thermal current limit Ith matches the AC-15 figure at 0.3 A — the contacts are sized for that continuous current regardless of load type. Overvoltage category III and a 4 kV surge voltage resistance mean it's rated for fixed-installation distribution panels, not just final circuits.
Panel integration and wiring
Strip the wire 15 mm (0.6 in) for the screw-clamp terminals. Pollution degree 3 means the contact gap tolerates conductive dust and humidity typical in industrial enclosures — no derating needed for a standard IP54 panel interior. The 7 mm width lets you stack multiple auxiliaries across the breaker's accessory slots without consuming extra DIN-rail space — useful when you need both a NO signal to the PLC and an NC interlock for a safety circuit.