Siemens 3TK2804-0BB4 Thermal Overload Relay Module

Siemens 3TK2804-0BB4 is a compact safety-relay module that consolidates contactor functionality for enabling and signaling safety circuits in industrial control systems. It is DC 24 V coil operated and provides a versatile contact configuration consisting of four normally open contacts (4NO) plus an additional NO/NC pair (1NO+1NC), enabling signaling and interlock logic within a single assembly. Designed for integration with Siemens power modules, it works in conjunction with the 3SK1230 power module, with guidance in the related power-module documentation to ensure correct connection and use. This module is intended for safety-circuit applications such as emergency-stop signaling, interlocks, and other protective devices, helping to monitor and control safeguarding paths without requiring separate relays for each function. Engineers typically employ the 3TK2804-0BB4 to streamline safety wiring and reduce component count in control panels and compact machinery, delivering reliable state signaling and control for safeguarding logic in motor-protection and line-protection schemes.