The GEC Alsthom MVAX12B1DB0758A is a high-performance auxiliary relay designed for flag indication and contact multiplication within electrical protection and control schemes. As part of the M-Series, it is built for long-term reliability in utility and industrial substation environments.
Product Parameters (Datasheet)
- Model Number: MVAX12
- Full Part Number: MVAX12B1DB0758A
- Rated Voltage (Vx): 110-125V DC
- Relay Type: Auxiliary Flag Indicator and Multi-contact Relay
- Contact Configuration: Typically 4 contacts (Specific to the B1DB code, often 4 N/O or 2 N/O + 2 N/C)
- Reset Type: Hand Reset (Mechanical flag and contact reset)
- Operating Time: Extremely fast response for trip circuit supervision or signaling
- Mounting: Size 1/2N or Size 2 modular draw-out case
- Burden: Low power consumption to prevent excessive drain on the station battery
- Compliance: IEC 60255 compliant for protective relaying standards
Country of Origin
This relay was engineered and manufactured by GEC Alsthom (now part of the GE Grid Solutions / Alstom legacy) in the United Kingdom or France.
Application Fields
The MVAX series is widely used across power infrastructure for:
- Trip Circuit Supervision: Monitoring the integrity of circuit breaker trip coils.
- Flag Indication: Providing a clear, mechanical visual “target” for maintenance crews to identify which protection zone has tripped.
- Contact Multiplication: Expanding a single protection signal into multiple outputs for SCADA, alarms, and lockout functions.
- Interlocking Logic: Managing complex permissive sequences in high-voltage switchyards.
- Power Plants: Handling auxiliary logic for turbine and generator safety systems.
Product Usage Instructions
- Mounting: Secure the relay case into the panel. Slide the MVAX12 module into the case until the connectors engage.
- Wiring: Wire the coil to the 110-125V DC control bus. Ensure polarity is correct according to the label diagram to ensure the flag mechanism operates correctly.
- Resetting: Once the relay has operated, the mechanical flag will be visible behind the clear cover. After the fault is cleared, manually press the reset button on the front of the relay to return the contacts to their normal state.
- Testing: Periodically use a secondary injection set to verify that the relay picks up at the specified minimum operating voltage (typically 60-80% of rated Vx).
- Maintenance: Keep the front cover closed to prevent dust from interfering with the delicate mechanical latches and flags.
Product Technical Description
The MVAX12B1DB0758A is a “latching” type auxiliary relay. Technically, it uses a high-grade magnetic coil to move an armature that simultaneously switches the electrical contacts and releases a mechanical indicator (the flag). The B1DB revision indicates a specific internal configuration designed for high-speed operation with minimal contact bounce. Because it is a hand-reset model, it is ideal for “Lockout” applications where a system must not be restarted until an operator has physically inspected the relay and manually reset the flag.
Q&A (Common Questions)
Q: Can I use this relay on a 220V DC system? A: No, the MVAX12B1DB0758A is specifically rated for 110-125V DC. Applying 220V will eventually burn out the coil.
Q: What is the difference between MVAX and MVAJ? A: MVAX is generally used for auxiliary signaling and flag indication, whereas MVAJ is a high-speed tripping relay specifically designed to handle the heavy currents required to trip circuit breaker coils.
Q: Does the flag drop automatically when the power is removed? A: No, the “Hand Reset” models require a physical push of the button to clear the flag, even if the electrical signal is gone.
Q: Is the case included with this part number? A: Usually, this part number refers to the internal relay module. If you are doing a new installation, you must ensure you have the matching M-Series case.
Similar Model Recommendations
- GEC Alsthom MVAX11 (Single element version)
- GEC Alsthom MVAX31 (Three element version in a larger case)
- Alstom MVAA (General auxiliary relay without flag)
- Areva MVAJ101 (High-speed tripping relay companion)
- GE Grid MVAX12B1DB0758A (Modern GE-branded identical replacement)
For technical support or to request a quote for the GEC Alsthom MVAX12B1DB0758A, please contact our substation equipment specialists.
