SIEMENS 3TK2827-1AL21 SIRIUS Safety Relay

Overview

SIEMENS 3TK2827-1AL21 is a SIRIUS safety relay with relay enabling circuits, control supply voltage 230 VAC, 45 mm width, screw terminal connection. 3TK2827-1AL21 provides 2 instantaneous NO enabling contacts and 2 adjustable delayed NO enabling contacts (0.05–3 s), plus 1 NC signal contact, supporting monitored start. It is used for emergency stop, safety gate and machine safety circuit control. This SIEMENS 3TK2827-1AL21 is widely stocked as spare safety control unit for legacy machine safety assemblies.

Features

SIEMENS 3TK2827 Safety Relay combines instantaneous safety output and configurable off-delay safety output, suitable for applications requiring controlled delayed shutdown such as fan coast-down, roller and conveyor safety stop.3TK2827-1AL21 adopts monitored start mode, requiring manual reset after safety trip to prevent automatic restart hazard. It has integrated cross-wire short circuit detection for dual-channel safety inputs. This safety relay has front panel LED indicators for power, safety status and fault diagnosis. It can be expanded with 3TK2830 extension modules to add more safety contacts. It complies with EN ISO 13849-1, IEC 61508, achieves SIL 3 / SIL 2, PL e / PL d. It is EMC compliant, CE certified, designed for 24/7 cabinet operation.

Specifications

SIEMENS 3TK2827-1AL21 SIRIUS Safety RelayBrand: Siemens Series: SIRIUS 3TK28 Model: 3TK2827-1AL21 Control supply: 230 VAC Width: 45 mm Terminal type: screw terminal Safety enabling contacts: 2 × NO instantaneous 2 × NO delayed, delay range 0.05 s ~ 3 s Signal contact: 1 × NC Start mode: monitored start Safety level: SIL 3 / SIL 2, PL e / PL d Mounting: DIN rail Protection class: IP20 Ambient temperature: -25℃ ~ +55℃ Status: legacy Siemens safety relay spare, successor 3SK series

Principle

SIEMENS 3TK2827-1AL21 receives dual-channel safety signal from emergency stop button or safety switch. This Safety Relay evaluates input signal and fault condition. When safety condition is triggered, instantaneous safety contacts open immediately; delayed contacts open after preset time expires. The NC signal contact outputs trip status to PLC or alarm circuit. Monitored start logic prevents automatic restart after power recovery or fault reset.

Applications

SIEMENS 3TK2827-1AL21 is deployed in packaging machinery, woodworking machines, printing equipment, conveyor systems and machine tools. It executes emergency stop, safety guard interlock and delayed safe stop functions. SIEMENS 3TK2827-1AL21 is stocked as spare safety relay for machine safety control assemblies.