The GEC Alsthom MVAX31C1CD0754A is a high-speed, multi-contact auxiliary tripping relay from the MVAX series. Designed for use in high-security protection schemes, this relay acts as a “master trip” or signal multiplication unit. It receives a single command from a primary protection relay (such as an overcurrent or differential relay) and simultaneously initiates multiple actions, such as tripping several circuit breakers, locking out control circuits, and triggering remote alarms.

 

Product Parameters and Technical Specifications

The MVAX31 series is built for extreme reliability and high-speed operation in utility substations.

• Model Number: MVAX31C1CD0754A
• Relay Type: High-Speed Multi-Contact Auxiliary Relay
• Contact Configuration: 8 or 16 contacts (Depending on internal “C1” configuration; typically 8 NO/NC combinations)
• Operating Speed: Less than 10ms (High-speed tripping)
• Auxiliary Voltage: 110V – 125V DC (indicated by the “75” coding)
• Reset Type: Hand Reset (indicated by the “C” in the suffix, providing a lockout function)
• Burden: Low burden during initiation to prevent overloading primary relay contacts.
• Mounting: Standard M-series draw-out modular case.

 

Product Datasheet Summary

The MVAX31C1CD0754A datasheet highlights its “High-Slam” contact design, which ensures positive electrical connection even under heavy vibration. The “C1” variant is specifically designed for applications where high-speed operation is critical to maintaining system stability. The unit includes a mechanical flag indicator that drops when the relay is energized, providing a clear visual signal to maintenance personnel. As a “Hand Reset” model, the relay stays in the tripped position until physically reset by an operator, ensuring that a fault must be acknowledged before the system can be re-energized.

 

Country of Origin

This protection module was manufactured in the United Kingdom, originating from the GEC Alsthom (later Alstom/GE) Stafford facility, a global leader in protection technology.

 

Application Fields

The MVAX series is a cornerstone of sophisticated protection logic:

• Busbar Protection: Simultaneously tripping all breakers connected to a faulted bus section.
• Transformer Protection: Coordinating the simultaneous trip of both HV and LV breakers.
• Generator Control: Initiating emergency shutdown sequences and turbine trips.
• Lockout Schemes: Preventing the closing of circuit breakers until a fault has been fully investigated and the relay manually reset.

 

Product Usage Instructions

1. Installation: Slide the MVAX31 module into its horizontal or vertical case. Ensure the locking handle is fully engaged to establish electrical contact.
2. Wiring: Connect the trip output from the primary relay to the MVAX coil terminals. Wire the output contacts to the various breaker trip coils and alarm inputs.
3. Resetting: If the relay trips, the mechanical flag will drop. After the fault is cleared, push the reset button on the front of the relay to return the contacts to their normal state.
4. Maintenance: Periodically perform a functional test using the “Trip” button (if equipped) or by injecting a test signal to ensure all output contacts are operating simultaneously.

Technical Description

The MVAX31C1CD0754A operates on an attracted-armature principle, but with a highly optimized magnetic circuit to achieve sub-10ms response times. The “Static” or semi-static nature of the auxiliary components ensures that the relay does not suffer from contact bounce, which is critical when driving heavy-duty trip coils. The internal circuitry is designed to handle the high inductive loads associated with breaker trip coils, featuring heavy-duty silver-alloy contacts that can interrupt high currents without welding.

 

Q&A – Frequently Asked Questions

Q: What is the difference between MVAX and MVAA relays? A: While both are auxiliary relays, the MVAX series is generally designed for higher speeds and is often used as a “Master Trip” or “Lockout” relay, whereas the MVAA is a general-purpose auxiliary relay for signal multiplication.

Q: Can this relay be used on an AC auxiliary supply? A: No, the MVAX31C1CD0754A is designed for DC station batteries (110V-125V). Using AC power may result in “chatter” or failure of the high-speed armature.

Q: Does the relay provide visual indication of a trip? A: Yes, it features a mechanical target (flag). On this “Hand Reset” model, the flag serves as a persistent reminder that a trip occurred until it is manually cleared.

Q: Where can I find more MVAX series relays and spare parts? A: You can find the GEC Alsthom MVAX31C1CD0754A and other legacy protection components through specialized industrial automation and power system suppliers.

 

Recommended Similar Models

1. GEC Alsthom MVAX11 – A smaller version with fewer output contacts.
2. GEC Alsthom MVAA11 – General purpose auxiliary relay for less time-critical logic.
3. GEC Alsthom MVAJ – A related family of high-speed tripping relays with similar characteristics.
4. Alstom MiCOM P19x – The modern numerical equivalent for complex auxiliary and logic schemes.
5. GEC Alsthom MMLG – Test blocks often used in the same panel to safely test MVAX trip circuits.