The Siemens 5SY1708-2 is a 1-pole device circuit breaker with an integrated auxiliary switch (normally open contact), part of the SENTRON range. It carries an F1 tripping characteristic rated at 8 A, designed for AC operation at 230 V (50/60 Hz) and DC operation at 60 V, with a breaking capacity of 3 kA AC per IEC 60934.
The F1 characteristic is a fast-acting curve with a defined short-circuit threshold — it sits between standard B and C curves in speed, intended for protecting sensitive semiconductor loads or control circuits where you need to clear a fault before the silicon lets go. The 1P+AS pole design means the auxiliary switch shares the same 18 mm width as the main pole, so it fits in a single modular unit on the DIN rail. Mounting position is horizontal or vertical, and the IP20 finger-safe housing is standard for enclosed panel use.
Rated under IEC / DIN EN 60934 (equipment circuit breakers) and UL1077 (supplementary protectors), so it is accepted in both IEC and North American panels as a supplementary overcurrent device. Vibration resistance per IEC 60068-2-6 is confirmed.