ALSTOM MVAJ105RA0802A Service-Ready Spare Part for Industrial Maintenance

ALSTOM MVAJ105RA0802A Service-Ready Spare Part for Industrial Maintenance

The ALSTOM MVAJ105RA0802A is a field-proven protection relay from the MVAJ series, engineered for overcurrent and earth fault protection in medium-voltage switchgear, motor control centers, and distribution panels. For maintenance engineers managing aging protection systems, sourcing a verified, pre-tested MVAJ105RA0802A is critical to minimizing unplanned downtime and restoring system protection integrity without delay. NINERMAS stocks this unit as a service-ready spare, fully tested prior to shipment and backed by a 12-month warranty, supporting both emergency replacement and planned annual maintenance programs.

The MVAJ105RA0802A is widely deployed in power distribution substations, industrial plant protection circuits, and utility feeder protection schemes. Its compact electromechanical design provides reliable overcurrent trip characteristics with independent time-multiplier settings, making it a preferred choice for engineers maintaining legacy protection coordination schemes where modern numerical relays cannot be directly substituted without full protection study rework. Keeping a verified spare on the shelf eliminates the risk of extended outages caused by relay failure during peak production periods.

Spare Maintenance Table

Maintenance Planning for Continuous Operation

When replacing the MVAJ105RA0802A in the field, a disciplined maintenance approach requires inspecting the entire protection circuit, not just the relay itself. Begin with the current transformer (CT) secondary wiring and terminal blocks — loose or corroded CT connections are a common cause of relay misoperation and must be verified before energizing the replacement unit. Check the auxiliary DC supply fuse and the associated DC distribution board for voltage stability; an unstable auxiliary supply is a leading cause of relay contact wear and spurious trips in MVAJ-series installations.

Inspect the trip circuit supervision relay and the associated lockout relay (86 relay) for contact condition and coil continuity. In motor feeder protection panels, the contactor auxiliary contacts and the motor protection relay (such as the ALSTOM MFAC or MCGG series) should be checked for coordination with the MVAJ105RA0802A trip settings. For substation feeder protection, verify the intertripping scheme and the associated ALSTOM MVTT or MVTF time-delay relay settings remain consistent with the protection coordination study after relay replacement.

Terminal block condition is frequently overlooked during relay replacement. Inspect the relay panel terminal strips for tightness, insulation condition, and correct ferrule labeling. Where the MVAJ105RA0802A is installed in a draw-out relay case, inspect the case contacts and the plug-in connector for oxidation. Replace the case if contact resistance is elevated. For installations with pilot wire protection or inter-panel signaling, check the associated signal isolators and surge protection devices on the pilot wire terminals.

Procurement engineers should note that the MVAJ series has been superseded in new installations by numerical relays such as the ALSTOM MiCOM P120 or P140 series, but direct electromechanical replacement remains the preferred strategy for legacy panels where protection coordination records are incomplete or where numerical relay retrofit costs are not justified. Maintaining a minimum stock of one MVAJ105RA0802A per critical feeder, alongside spare CT shorting links, auxiliary fuses, and relay case contacts, is recommended practice for plants operating with annual maintenance windows.

Site Replacement Workflow

Before removing the MVAJ105RA0802A from service, confirm that the feeder or motor circuit is isolated, locked out, and tagged in accordance with site LOTO procedures. Short-circuit the CT secondary terminals using approved CT shorting links before disconnecting any CT wiring — open-circuiting a live CT secondary is a serious safety hazard and will damage the CT. Record the existing time-multiplier setting (TMS) and current setting (plug setting) from the outgoing relay before removal, and verify these settings are replicated exactly on the replacement unit prior to installation.

After installing the MVAJ105RA0802A replacement, perform a secondary injection test using a relay test set to verify the trip time at the set current multiple. Confirm the trip output contact operates the correct lockout or trip relay in the panel. Check the flag indicator reset mechanism and confirm the relay resets cleanly after test injection. Restore CT wiring, remove CT shorting links, and verify auxiliary supply voltage at the relay terminals before returning the feeder to service. Document the replacement in the site maintenance register with the new relay serial number, test results, and date of installation.

For plants managing multiple MVAJ-series relays across a switchboard, a phased replacement program — replacing the oldest units during scheduled outages rather than waiting for in-service failure — significantly reduces the risk of simultaneous protection failures during fault conditions. NINERMAS supports long-term supply agreements for MVAJ series relays, enabling procurement teams to secure stock commitments aligned with multi-year maintenance schedules.

Spare Parts Support FAQ

Q1: Is the MVAJ105RA0802A compatible with other MVAJ series relay cases?
The MVAJ105RA0802A is designed for use in standard ALSTOM/GEC MVAJ relay cases. Compatibility with specific case variants (flush, draw-out, or surface mount) should be confirmed against the original panel documentation. NINERMAS technical support can assist with compatibility verification based on your panel drawings or existing relay nameplate data.

Q2: What pre-shipment testing is performed on the MVAJ105RA0802A?
Each unit undergoes functional testing of the overcurrent trip element, earth fault element, time-multiplier mechanism, output contacts, and flag indicator prior to shipment. Test records are available upon request. The 12-month warranty covers functional defects identified after installation under normal operating conditions.

Q3: Can NINERMAS support long-term supply of MVAJ105RA0802A for multi-year maintenance programs?
Yes. NINERMAS offers stock commitment programs for critical spare parts including MVAJ series relays, supporting procurement engineers who require guaranteed availability across multi-year plant maintenance cycles. Contact our team to discuss minimum stock levels, lead time commitments, and pricing for annual supply agreements.

Q4: What is the recommended inventory strategy for MVAJ105RA0802A in a substation or plant environment?
For substations or plants with multiple MVAJ-series feeders, maintaining a minimum of one tested spare per critical feeder is recommended. For facilities with more than five MVAJ relays in service, a pooled spare strategy — holding two to three tested units centrally — balances inventory cost against outage risk. NINERMAS can advise on spare parts rationalization based on your installed base.