Product Core Brief
- Model: MVAJ27L1FB0784D
- Brand: ALSTOM / GE Vernova
- Series: ALSTOM MVAJ Trip/Auxiliary Relay Family
- Core Function: Electromechanical trip/auxiliary relay used to interface protection logic with circuit breaker trip coils, interlock circuits, alarms, and DC control circuits.
- Product Type: Trip Relay / Auxiliary Relay / Draw-Out Relay
- Key Specs: DC coil | Multiple Form C changeover contacts | Draw-out case | Mechanical flag indicator | No communication interface
- Condition: New Original / New Surplus
Product Introduction
ALSTOM MVAJ27L1FB0784D is a heavy-duty electromechanical trip/auxiliary relay from the ALSTOM MVAJ relay family, now referenced under GE Vernova. It is designed for protection and control panels where a reliable, fast-operating relay is required between protective devices and circuit breaker trip circuits.
The relay is housed in a draw-out case with rear terminal connections, allowing the relay element to be withdrawn for testing or replacement without disturbing permanent panel wiring. It provides multiple changeover contacts for tripping, interlocking, alarm signaling, and auxiliary DC control duties. A front mechanical flag or indicator is commonly fitted to confirm relay operation during commissioning and post-fault inspection.
Public spare listings describe MVAJ27L1FB0784D as a high-speed trip/auxiliary relay with sub-20 ms pickup, Form C contacts, and no communication ports. Some third-party pages incorrectly describe it as a digital protective relay with overcurrent, overvoltage, ground fault, Modbus, or Ethernet functions; those descriptions are inconsistent with the MVAJ trip/auxiliary relay family and should not be used as the sole basis for replacement. Always verify the installed nameplate, coil voltage, contact arrangement, and panel drawing before procurement.
Key Technical Specifications
| Parameter | Value |
|---|---|
| Full Model | ALSTOM |
| Product Type | Electromechanical Trip/Auxiliary Relay |
| System Platform | ALSTOM MVAJ Trip Relay Family |
| Core Function | Breaker trip, interlock, alarm, and auxiliary DC control switching |
| Coil Voltage | DC coil; commonly 110–125 VDC for this build code in many listings — confirm from nameplate |
| Contacts | Multiple changeover (Form C) contacts; resistive duty commonly around 10 A at 250 VAC / 30 VDC depending on build |
| Operate Time | Typically sub-20 ms pickup for trip/auxiliary duty |
| Indicator | Mechanical flag/indicator for operation confirmation |
| Installation | Flush panel mounting in draw-out case; rear screw/plug-in terminals |
| Communication | None |
Quality Control Process
- Visual and code check: Confirm MVAJ27L1FB0784D labeling, case condition, terminals, flag/indicator, and front hardware.
- Coil verification: Confirm DC coil voltage matches the installed nameplate and panel drawing before energizing.
- Contact operation check: Verify pickup, drop-off, contact bounce behavior, and changeover contact operation.
- Draw-out mechanism check: Confirm smooth insertion/withdrawal and correct rear terminal engagement.
- Final packing: Record test results, apply asset labels, and ship with terminal and case protection.
Replacement Pitfall Guide
❗ Confirm coil voltage from the nameplate. MVAJ27 variants may use different DC coil ratings; applying the wrong voltage can prevent tripping or damage the coil.
❗ Verify contact arrangement and current rating. The number of Form C contacts and their making/breaking capacity must match the trip, interlock, and alarm circuits.
❗ Do not treat it as a digital protection relay. MVAJ27L1FB0784D is an electromechanical trip/auxiliary relay with no settings menus, protection algorithms, or communication ports.
❗ Check draw-out case compatibility. The replacement must match the case footprint, terminal layout, and mounting cutout to avoid panel rewiring.
Keep these in mind and you’ll cut 90% of rework time.
Compatibility Matrix & Benchmarks
| Original Model | Replacement / Successor Model | Compatibility Level | Migration Notes |
|---|---|---|---|
| ALSTOM | ALSTOM | Direct | Like-for-like replacement when coil voltage, contact arrangement, and case match. |
| ALSTOM | Other MVAJ27 variant | Needs Adaptation | Confirm coil voltage, contact count, flag/indicator, and case dimensions. |
| ALSTOM | Other ALSTOM/GE MVAJ trip relay | Needs Adaptation | Requires verification of coil, contacts, operate time, and panel wiring. |
| ALSTOM | Modern auxiliary/trip relay | Needs Adaptation | Requires case, terminal, coil, and contact mapping verification. |
- Typical use: MV/HV switchgear, feeder/transformer/generator protection panels, DC trip circuits, intertripping schemes, and auxiliary control panels.
- Key verification points: MVAJ27L1FB0784D part number, coil voltage, contact configuration, draw-out case type, and panel wiring drawing.
