The Siemens 5SM2827-8 is a SENTRON residual current unit (RC unit) designed for use with the 5SP4 series. It is a 2-pole, type A, selective device rated at 100 A and a tripping fault current of 1000 mA at 230 V AC. The selective design (type S) means it incorporates a short time delay, allowing downstream RCDs to trip first on a ground fault, so only the faulted branch is isolated — the main feeder stays live. This coordination is critical in distribution boards serving multiple sub-circuits.
Rated at 100 A continuous current, this RC unit handles the full load of a main feeder or heavy sub-main. The 1000 mA trip threshold is intentionally high — it prevents nuisance tripping on systems with natural leakage (long cable runs, multiple loads) while still providing earth-fault protection. Type A covers the majority of modern commercial and light industrial panels. The surge current resistance of 5 kA (8/20 µs) means it withstands lightning-induced surges without damage.
Installation depth is 70 mm. Mounting position is any. Supply connection can be top or bottom.