The GEC Alsthom MAVS02D1AB0751D is a high-precision static check-synchronizing relay belonging to the MAVS series. This relay is designed to safeguard power systems by ensuring that two separate AC voltages (typically a busbar and an incoming generator or line) are within acceptable limits of phase angle, voltage magnitude, and frequency before allowing a circuit breaker to close. By preventing out-of-phase synchronization, the MAVS02D1AB0751D protects generators, transformers, and switchgear from the catastrophic mechanical and electrical stresses caused by faulty coupling.

 

Product Parameters and Technical Specifications

The MAVS series is engineered for high stability and reliable operation in utility-grade substations.

• Model Number: MAVS02D1AB0751D
• Relay Type: Static Check-Synchronizing Relay
• Configuration: Dual-input (Bus vs. Line/Generator)
• Rated Voltage (Vn​): Typically 110V AC (Standard PT secondary)
• Auxiliary Supply: 110V – 125V DC (indicated by the “75” coding)
• Phase Angle Setting: Adjustable range (typically 10° to 40°)
• Voltage Difference Limit: Fixed or adjustable percentage of Vn​
• Timer Characteristic: Definite time delay (indicated by the “D” in the model)
• Mounting: Standard M-series draw-out modular case

 

Product Datasheet Summary

The MAVS02D1AB0751D datasheet highlights its solid-state architecture, which provides superior accuracy over electromagnetic induction-type synchronizers. The unit continuously monitors the vector difference between the two voltage inputs. The “02” designation identifies this as a specific configuration within the MAVS family, often including “Dead Line” or “Dead Bus” charging features that allow the breaker to close if one side of the circuit is intentionally de-energized. The draw-out case design includes automatic CT/PT shorting and disconnection logic, facilitating safe maintenance and secondary injection testing while the panel is live.

 

Country of Origin

This protection module was manufactured in the United Kingdom at the GEC Alsthom Stafford plant, a global leader in power protection and control engineering.

 

Application Fields

The MAVS series is a critical component in synchronized power networks:

• Power Plants: Ensuring safe synchronization of synchronous generators to the national grid.
• Transmission Substations: Managing the re-closure of tie-lines and bus-couplers.
• Industrial Cogeneration: Controlling the coupling of private power generation with the utility provider.
• Automatic Reclosing Schemes: Used as a permissive element to ensure the line is stable before an automated re-close attempt.

 

Product Usage Instructions

1. Installation: Secure the M-size case into the relay rack. Ensure the grounding strap is connected to the station earth.
2. Phase Correlation: Carefully wire the Bus PT and Line PT to the correct terminals. Correct phase rotation and polarity are essential for the relay to accurately calculate the phase angle.
3. Parameter Setting: Adjust the phase angle limit (Δϕ) and voltage difference (ΔV) thresholds using the front-panel dials based on the generator manufacturer’s or utility’s requirements.
4. Testing: Perform a secondary injection test using a dual-source test set. Simulate various phase offsets and verify that the relay output contacts only close when the conditions are within the set window.

Technical Description

The MAVS02D1AB0751D operates by comparing two analog AC signals. Internal circuitry extracts the phase and magnitude data, feeding them into a comparator logic gate. The “Check-Sync” contact will only energize if:

1. Both voltages are above the “live” threshold.
2. The voltage difference is within the set tolerance.
3. The phase angle remains within the permitted window for the duration of the set time delay. The use of static electronic components ensures that the relay has a very low burden on the potential transformers and remains immune to frequency drifting, which is common during the startup phase of a generator.

 

Q&A – Frequently Asked Questions

Q: What does “Static” mean in the context of the MAVS series? A: It indicates that the measurement and logic functions are performed by solid-state electronic components (transistors and ICs) rather than moving mechanical parts, leading to better reliability and precision.

Q: Does this relay provide “Auto-Sync” functionality? A: No, the MAVS is a check-synchronizing relay. It acts as a permissive gate that allows a manual or automated command to proceed only if conditions are safe. An “Auto-Synchronizer” is a different device that actively adjusts the engine speed and voltage.

Q: Can this relay handle a “Dead Bus” close? A: Yes, many MAVS02 variants include logic to allow breaker closure if the busbar is dead and the line is live (or vice versa), which is essential for restoring power after a blackout.

Q: Where can I source the MAVS series and related GEC Alsthom parts? A: You can find the GEC Alsthom MAVS02D1AB0751D and other legacy protection modules through specialized industrial automation and power grid equipment suppliers.

 

Recommended Similar Models

1. GEC Alsthom MAVS01 – A simplified version without dead-line/dead-bus features.
2. GEC Alsthom SKD – A legacy electromechanical check-sync relay often replaced by MAVS.
3. Alstom MiCOM P14x – The modern numerical successor to the MAVS static series.
4. GEC Alsthom MCAA – Auxiliary relay used to provide additional closing contacts.
5. GEC Measurements VAV – A voltage-sensing relay often used in conjunction with synchronization schemes.