The GEC Alsthom MVAA11B1BA0781C is a high-reliability auxiliary relay designed for use in protection and control schemes, providing essential contact multiplication, signal isolation, and circuit interlocking in high-voltage environments.
Product Parameters (Datasheet)
- Model Number: MVAA11B1BA0781C
- Relay Series: MVAA (Standard Auxiliary Relay)
- Rated Voltage (Vn): 110V / 125V DC (Dual rated)
- Burden: Low burden (Typically < 3W during operation)
- Contact Arrangement: Multi-contact configuration (Standardized for the 11B variant)
- Reset Type: Self-resetting (Instantly returns to normal state upon removal of coil power)
- Operating Time: Rapid response (Typically 15ms to 25ms)
- Insulation: 2kV rms for 1 minute
- Case Size: Size 2 (Vertical modular drawout case)
- Enclosure Rating: IP50 (Dust protected)
Country of Origin
This protective component is manufactured by GEC Alsthom (now part of GE Grid Solutions) in the United Kingdom, specifically at the Stafford center of excellence for relay engineering.
Application Fields
The MVAA series is a versatile “workhorse” found in various utility and industrial sectors:
- Substation Control: Used for tripping, interlocking, and alarm logic in switchgear panels.
- Transmission Lines: Providing galvanic isolation between primary protection relays and remote signaling units.
- Power Generation: Acting as a heavy-duty interface for turbine-generator emergency shutdown systems.
- Industrial Plants: Managing complex logic sequences for large AC motors and medium-voltage distribution.
Product Usage Instructions
- Mounting: Install the relay in its matching size 2 drawout case. The modular design allows the relay to be removed without disturbing the external panel wiring.
- Wiring: Connect the 110/125V DC control supply to the coil terminals. Ensure all wiring is secured to the rear terminal blocks using appropriate ring or spade terminals.
- Polarity: While MVAA relays are typically robust, always verify DC polarity if the specific variant includes internal LED indicators or suppression diodes.
- Integration: Use the dry contacts to switch auxiliary circuits, such as local alarm lamps, remote SCADA inputs, or circuit breaker trip coils.
- Maintenance: Periodically check for contact wear or oxidation. The drawout feature permits quick secondary injection testing to verify pick-up and drop-out voltage levels.
Product Technical Description
The MVAA11B1BA0781C functions as an attracted-armature auxiliary relay. Technically, it is engineered for long-term reliability in environments with high electromagnetic interference. The “11B” designation indicates its specific contact stack and internal wiring logic, while the “BA” suffix defines the electrical rating for the 110/125V DC range. Unlike tripping-specific relays (like the MVAJ), the MVAA is a general-purpose auxiliary unit, meaning it stays energized as long as the control signal is present and resets immediately when the signal is removed.
Q&A (Common Questions)
Q: Can I use this relay on an AC control circuit? A: No, the 0781C variant is specifically wound for 110/125V DC. Applying AC will cause the relay to chatter (vibrate) and potentially damage the coil.
Q: Does this relay have a manual reset flag? A: Standard MVAA models are self-resetting and usually do not feature a mechanical flag unless specifically ordered as a “latching” or “flagged” variant.
Q: Is this relay compatible with older English Electric or GEC models? A: Yes, the MVAA is the direct technical successor to the English Electric and GEC “M-series” auxiliary relays, maintaining the same physical footprint and terminal logic.
Q: What is the maximum current the contacts can break? A: The contacts are typically rated for 5A to 10A continuously, but the breaking capacity for inductive DC loads is significantly lower. Always use external surge suppression for high-inductance trip coils.
Similar Model Recommendations
- GEC Alsthom MVAA11A (Alternative contact arrangement)
- GEC Alsthom MVAA12 (High-speed variant)
- GEC Alsthom MVAJ (High-speed tripping relay variant)
- GEC Alsthom MVAX (Trip circuit supervision variant)
- GEC Alsthom MVAS (Time-delay auxiliary variant)
For more information on the GEC Alsthom MVAA11B1BA0781C and our full catalog of protective relay solutions, please contact our technical sales team.
