The RXMVB 4 (RK 251 402-AP) is a high-speed auxiliary relay manufactured by ABB, primarily used in power system protection and control schemes. As a member of the COMBIFLEX modular relay system, it is engineered for high reliability, fast operation times, and heavy-duty contact performance, making it a critical component for critical infrastructure.
Product Specifications
| Feature | Details |
| Model Number | RXMVB 4 |
| Part Number | RK 251 402-AP |
| Device Type | High-Speed Auxiliary Relay |
| System Compatibility | ABB COMBIFLEX Modular System |
| Mounting | Plug-in unit (requires RX base) |
| Weight | Approximately 0.6 kg – 1.0 kg |
| Country of Origin | Sweden / Various (ABB Global) |
Application Fields
This relay is specifically designed for protective relaying applications in high-voltage and medium-voltage switchgear. Its primary roles include:
- Trip Circuit Multiplication: Providing multiple output contacts for tripping circuit breakers.
- Signal Interlocking: Facilitating complex logic sequences in protection cabinets.
- Automation Control: Acting as an interface between protection relays and switchgear control mechanisms.
Product Usage Instructions
Installation should only be performed by qualified electrical personnel. The RXMVB 4 is designed to be plugged into an ABB RX-type terminal base. Ensure the mechanical keying (if applicable) matches the base to prevent improper insertion. Before inserting, verify that the control voltage rating of the relay coil matches the system supply voltage to avoid coil burnout. Once inserted, ensure the front-locking handle is secure, and check that all external wiring connections to the terminal block are tightened to the specified torque.
Frequently Asked Questions
Q: What is the main advantage of the RXMVB 4?
A: It offers extremely fast operating times and high-capacity contacts, ensuring reliable operation of circuit breakers even in demanding, high-fault-current environments.
Q: Can this relay be mounted directly on a DIN rail?
A: No, it is designed for the ABB COMBIFLEX system. It must be mounted into an appropriate RX terminal base or a dedicated equipment frame.
Q: How do I verify the relay status?
A: You can perform a functional test by energizing the coil under controlled conditions and verifying the change-of-state of the output contacts using a multimeter or the integrated status flag (if equipped).
Q: Is the RK 251 402-AP specific to a certain voltage?
A: Yes, the “RK 251 402-AP” code denotes a specific configuration. Always check the label on the relay front plate to confirm the exact rated voltage (e.g., 24V, 48V, 110V, or 220V DC) before applying power.
