Description

The Yokogawa ALR121-S00 is a high-reliability safety relay output module designed for integration into Yokogawa’s ProSafe-RS safety instrumented system (SIS). This critical safety component provides the essential interface between the safety controller and final control elements, executing safety commands by switching loads in emergency situations. The Yokogawa ALR121-S00 is specifically engineered to handle relay output functions in safety-critical applications such as emergency shutdown systems (ESD), fire and gas systems (FGS), and burner management systems (BMS). It operates as the last line of defense in safety loops, directly controlling actuators, valves, and other safety devices to bring processes to a safe state when predetermined conditions are violated.

Manufactured to meet rigorous international safety standards, the Yokogawa ALR121-S00 achieves Safety Integrity Level (SIL) 3 certification according to IEC 61508 and IEC 61511 requirements. The module incorporates redundant architecture and advanced diagnostic capabilities that continuously monitor both the module’s internal health and the status of connected field devices. This design ensures that any potential fault is detected and managed appropriately, maintaining the safety function even in the event of component failure. The Yokogawa ALR121-S00 represents Yokogawa’s commitment to providing reliable safety solutions that protect personnel, equipment, and the environment in the most demanding industrial applications.

The module’s robust design features high-capacity relay contacts, electrical isolation, and built-in diagnostics, ensuring reliable operation even in electrically noisy industrial environments. With its hot-swappable capability, the Yokogawa ALR121-S00 allows for maintenance and replacement without compromising system availability, significantly reducing downtime during maintenance operations. Its compatibility with Yokogawa’s engineering tools simplifies configuration, commissioning, and ongoing maintenance, making it an ideal choice for both new installations and modernization projects in process industries where safety and reliability are paramount concerns.

ALR121-S00 YOKOGAWA

Technical Specifications

Parameter Name	Parameter Value
Product Model	ALR121-S00
Manufacturer	Yokogawa Electric Corporation
Product Type	Safety Relay Output Module
Number of Channels	8 channels
Contact Type	Form C (SPDT)
Contact Rating	2 A @ 230 V AC, 2 A @ 30 V DC
Maximum Switching Voltage	230 V AC, 30 V DC
Maximum Switching Power	500 VA (AC), 60 W (DC)
Electrical Life	100,000 operations (rated load)
Mechanical Life	10,000,000 operations
Operating Temperature	-40°C to +70°C
Storage Temperature	-40°C to +85°C
Response Time	≤ 15 ms
Isolation	1500 V AC between field and system
Safety Certification	SIL 3 (IEC 61508/61511)
Diagnostics	Contact monitoring, coil monitoring

Main Features and Advantages

The Yokogawa ALR121-S00 delivers exceptional safety performance through its robust relay design and comprehensive diagnostic capabilities. The module features Form C (SPDT) contacts that provide both normally open and normally closed configurations, offering flexibility in safety circuit design. The relays are rated for high electrical loads, capable of switching up to 2A at 230V AC, making them suitable for direct control of various field devices without requiring additional contactors or amplifiers. The Yokogawa ALR121-S00 incorporates continuous self-diagnostics that monitor contact status, coil operation, and internal circuitry, ensuring that any potential failure is detected before it can compromise the safety function.

Enhanced safety and reliability: The Yokogawa ALR121-S00 is designed with de-energized-to-trip philosophy, ensuring that safety actions are executed even in case of power loss. The module’s high isolation rating (1500V AC) between field circuits and the control system provides protection against electrical noise, surges, and ground potential differences. This isolation, combined with the robust relay design, ensures reliable operation in harsh industrial environments where electrical interference could affect less robust components. The Yokogawa ALR121-S00 also features redundant configuration options, allowing for hot standby arrangements that maintain safety protection even during maintenance operations.

Maintenance and operational advantages: The Yokogawa ALR121-S00 offers significant maintenance benefits through its advanced diagnostic capabilities and hot-swappable design. The module provides detailed status information for each channel, including contact wear indication and predictive maintenance data, enabling planned maintenance before failures occur. The hot-swap capability allows for module replacement without system shutdown, significantly reducing maintenance downtime. The module’s integration with Yokogawa’s engineering tools simplifies configuration, testing, and documentation, supporting compliance with safety lifecycle management requirements and reducing overall cost of ownership.

Application Field

The Yokogawa ALR121-S00 is deployed across multiple high-hazard industries where safety instrumented systems are mandatory for risk reduction. In oil and gas facilities, the module serves in critical applications including emergency shutdown systems on offshore platforms, where it controls safety valves and shutdown devices. In refinery applications, the Yokogawa ALR121-S00 operates within fire and gas detection systems, activating alarm horns, flashing beacons, and emergency ventilation systems when hazardous conditions are detected. The module’s robust relay contacts ensure reliable operation of these critical safety functions even in the challenging environments encountered in oil and gas production and processing facilities.

Petrochemical and chemical processing plants utilize the Yokogawa ALR121-S00 in reactor emergency cooling systems, emergency pressure relief systems, and critical interlock circuits. The module’s high reliability and diagnostic capabilities ensure that safety actions are executed precisely when process parameters exceed safe operating limits, preventing runaway reactions, equipment damage, and potential environmental incidents. In power generation, particularly in nuclear and conventional thermal power plants, the Yokogawa ALR121-S00 provides safety-critical control of turbine emergency stop systems, boiler safety valves, and emergency core cooling systems where reliable operation is essential for public safety.

The pharmaceutical and specialty chemical industries also benefit from the Yokogawa ALR121-S00‘s capabilities for batch process safety applications where reliable isolation of process sections is critical to maintaining safe operating conditions. In each application, the module provides the reliable output switching necessary for implementing effective safety functions that protect human life, environmental assets, and capital equipment while ensuring regulatory compliance and operational excellence.

ALR121-S00 YOKOGAWA

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