Siemens 5ST3 020 Fault Signal Contact

Siemens 5ST3 020 Fault Signal Contact is a fault-signal accessory for SENTRON 5ST3 miniature circuit breakers that provides one normally open and one normally closed output to indicate a fault condition. It is compatible with Siemens 5SL, 5SY, 5SP RCBOs and 5SU1 RCBOs, as well as 5SV residual-current devices when paired with the appropriate handle coupler (5ST3805-1). The module carries a 1 NO + 1 NC contact arrangement and supports conductor connections from 0.5 mm² to 2.5 mm²; it is UL 489 compliant for miniature circuit breakers and designed for DIN rail mounting, with variants that use screw-terminal connections. The fault-signal contact typically requires a minimum load of 50 mA at 24 V to ensure reliable operation and is catalogued as 5ST3020-0HG (the 5ST3 020 family for fault signaling).