The Alstom MVAJ105RA0802A is a member of the well-known MVAJ series of self-resetting or hand-reset high-speed trip relays. These relays are widely used in power system protection schemes to provide high-speed isolation of faulty equipment by triggering circuit breakers. They are characterized by their reliability, fast operating times, and ability to handle high-burden trip circuits.
Product Specifications
| Feature | Specification Details |
| Product Name | Alstom (GE) MVAJ High-Speed Trip Relay |
| Model/Config | MVAJ105RA0802A |
| Manufacturer | Alstom (now part of GE Grid Solutions) |
| Operating Time | Typically < 10 ms (high-speed operation) |
| Reset Type | Hand/Electrical Reset (Dependent on configuration) |
| Application | Protection signaling and circuit breaker tripping |
| Contacts | Multiple high-capacity heavy-duty contacts |
Application Fields
The MVAJ series is a staple in critical infrastructure protection:
- Substation Automation: Acts as the final output interface between a protection relay (like a distance or differential relay) and the circuit breaker trip coil.
- Fault Isolation: Ensures that when a fault is detected by primary protection, the trip signal is multiplied and reinforced to ensure the breaker operates instantly.
- Industrial Switchgear: Used in heavy industrial power distribution to manage breaker tripping sequences in response to electrical faults.
- Power Plant Protection: Integral to the protection of generators, transformers, and large motors.
Product Usage Instructions
- Mounting: These relays are typically panel-mounted using a draw-out case design, allowing for easy testing and maintenance without disconnecting the rear wiring.
- Wiring: Ensure the trip circuit wiring is sized correctly to handle the high current pulses required by breaker trip coils. Always verify that the relay’s rated voltage matches your DC battery system (e.g., 110V DC, 220V DC).
- Resetting: For the MVAJ105 (hand-reset version), ensure that operators are aware that after a trip, the relay must be manually reset using the mechanical target/button on the front face before the circuit can be re-energized.
- Maintenance: Periodically check the mechanical integrity of the flag/target indicator. Ensure the contacts are clean and free of oxidation to maintain low contact resistance.
Frequently Asked Questions (Q&A)
Q: What is the primary function of the MVAJ series?
A: It is a “heavy-duty” relay. Standard protection relays (like IEDs) often have contacts that are not robust enough to handle the high current of a circuit breaker trip coil over a long lifetime. The MVAJ acts as a bridge, where the small signal from the protection relay energizes the MVAJ, which then uses its heavy-duty contacts to safely trip the breaker.
Q: How do I identify if the relay has operated?
A: The MVAJ105 features a mechanical “flag” or indicator that pops up when the relay has tripped. This provides visual confirmation to maintenance personnel of a protection operation even if the system has been de-energized.
Q: Is the MVAJ series still available?
A: Many MVAJ models have been phased out in favor of modern digital trip/lockout relays (like the GE Multilin series). However, they are still widely serviced, and refurbished units are available through specialized industrial parts suppliers for legacy system maintenance.
Q: Can I test the relay without tripping the circuit breaker?
A: Yes, you can perform functional testing by disconnecting the trip coil wiring (ensure it is safely isolated) and injecting the rated voltage into the relay coil while observing the operation of the output contacts using a multimeter.
