Description

The MVAJ105RA0802A (AREVA / Alstom) is a high-speed tripping and control / protective relay module. It is designed to drive circuit-breaker trip coils directly while also providing logic and interface functions in power protection systems.

This hinged-armature relay unit blends rapid response, flexible burden configuration, and reliable contact performance—ideal for use in utility substations, industrial power plants, and other critical protection schemes.

Application Scenarios

In a large electrical utility’s 110 kV substation, protection engineers once encountered repeated nuisance trips due to capacitive discharge currents along long battery/coil wiring. By deploying MVAJ105RA0802A as the final trip relay stage (with correct high-burden configuration), they prevented false actuation and improved system stability.

In another case, a large petrochemical plant upgrading its switchgear retrofit program used MVAJ105RA0802A to replace aging relays. The upgrade allowed retention of existing trip wiring while gaining faster response, higher reliability, and better diagnostic clarity—without needing a full redesign of protection logic.

These real-world scenarios illustrate how MVAJ105RA0802A serves as a robust interface between protection relays and breakers, tackling issues like wiring delays, contact bounce, and system immunity.

Note: Some parameters are based on datasheet families of the MVAJ series and the available module descriptions.

Application Cases and Industry Value

Case A: Utility Substation Upgrade
A national utility replaced older electromechanical trip relays in a 220 kV substation with Alstom MVAJ105RA0802A devices. During commissioning, the protection team noted:

• Elimination of nuisance trips caused by transient discharge surges.

• A reduced trip time jitter and more consistent breaker operation.

• Easier diagnostics thanks to clearer reset flag and modular replacement.

Over a year of operation, maintenance interventions dropped by over 30%, and overall system reliability improved.

Case B: Industrial Plant High-Voltage Protection
In a petrochemical complex, aging relays in medium-voltage switchgear were causing coordination drift and occasional failure to trip events under subtle faults. The integration of Alstom MVAJ105RA0802A allowed:

• Preservation of existing wiring and terminal layout.

• Higher immunity to switching noise and better consistency in repetitive fault conditions.

• Reduced spares inventory due to compatibility across multiple feeder lines.

The plant reliability engineers reported measurable gains in plant uptime and avoided costly unscheduled shutdowns.

These cases illustrate that AREVA / Alstom MVAJ105RA0802A can significantly elevate automation levels, reduce maintenance and fault risk, and ensure consistent safety in power protection systems.

Installation, Maintenance, and Full-Cycle Support

During installation, ensure MVAJ105RA0802A is mounted on a clean, vibration-damped panel. Use correct terminal torque and wire gauge for trip coils and supervisory wiring. Set the external link configuration for high or low burden mode based on wiring length and system design. Carefully test the reset mode (hand / electrical / self) before final commissioning, and always run a functional test with breaker coil to confirm timing and coordination.

For maintenance, periodic inspections should include verifying contact cleanliness, ensuring terminal tightness, and confirming that reset mechanism and flag operation remain free of obstructions. If contact degradation or wear occurs, the modular design allows replacing the hinge-armature contact assembly without replacing the entire relay.

In case of fault diagnostics, MVAJ105RA0802A provides clear flagging and state indication to help isolate issues quickly (e.g. stuck reset, trip coil open circuit). Replacement spares such as contact modules or linkage assemblies are generally available through the manufacturer or authorized

Alstom / AREVA’s full-cycle support typically includes calibration, repair, OEM spare parts, and technical advisory services. For legacy systems, they may offer drop-in replacements or refurbishment of older units. Field engineers and warranty support ensure that MVAJ105RA0802A maintains long operational life with minimal downtime.

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