The GEC Alsthom MAVS02D1AB0751D is a specialized high-performance check synchronizing relay from the celebrated MAVS series. Developed by GEC Alsthom (a legacy brand of Alstom and AREVA), this module is designed to ensure the safe and synchronized connection of two AC electrical systems, such as a generator to a busbar or two separate power grids. It prevents the catastrophic mechanical and electrical damage that can occur if a circuit breaker is closed when the systems are out of phase, making it an essential safety component for power stations and large industrial substations.

 

Technical Description & Parameters

The MAVS02D1AB0751D utilize precise electronic sensing to compare the voltage, frequency, and phase angle of two independent power sources.

• Model Number: MAVS02D1AB0751D
• Relay Type: Check Synchronizing Relay (Dual-Input)
• Voltage Rating: Typically 110V or 63.5V AC (Standard PT/VT secondary inputs)
• Phase Angle Limits: Adjustable range (typically 10° to 40°)
• Voltage Difference Limit: Adjustable (typically 5% to 20% of nominal)
• Frequency Difference (Slip): Integrated slip-frequency checking
• Auxiliary Power (AB Code): 24-125V DC (Wide-range DC supply)
• Contacts: High-integrity output contacts for circuit breaker closing permission
• Mounting: Standard draw-out case for easy maintenance and testing

 

Product Technical Description

The MAVS02D1AB0751D serves as a “permissive” device. It does not automatically adjust the generator speed; instead, it monitors the two systems and only allows the closing command to reach the circuit breaker when the phase angle, voltage, and frequency are within safe, pre-set limits. The “02” designation typically refers to a specific configuration of inputs, while the “D” suffix indicates a standard draw-out case that allows the relay to be removed from the rack without disturbing the backplane wiring.

 

Product Datasheet Essentials

This module features front-panel potentiometers for fine-tuning the phase angle and voltage acceptance windows. It includes a “Dead Bus” override feature, which can be configured via internal jumpers to allow the breaker to close if one side of the system is de-energized (essential for black-start conditions). The “1D” revision includes enhanced transient suppression and an internal watchdog circuit that monitors the health of the timing and logic components, ensuring that a component failure does not lead to an unsafe closing command.

 

Country of Origin

United Kingdom / France (GEC Alsthom Protection & Control)

 

Application Fields

The MAVS series is a critical safety element in:

• Power Generation: Synchronizing steam, gas, or hydro turbines to the national grid.
• Co-generation Plants: Managing the connection between onsite generation and utility power.
• Substation Automation: Controlling the bus-coupler breakers in complex double-busbar arrangements.
• Marine Engineering: Synchronizing multiple diesel generators on commercial vessels and oil rigs.

 

Product Usage Instructions

1. Installation: Slide the relay into its housing. Ensure the VT (Voltage Transformer) inputs from both the “Running” and “Incoming” sides are correctly connected to the rear terminals.
2. Setting Limits: Set the phase angle limit (e.g., 20°) and voltage difference (e.g., 10%) based on the inertia of your generator and the requirements of the utility provider.
3. Dead Bus Configuration: If your application requires closing onto a de-energized bus, verify that the “Dead Bus” enable jumpers are correctly positioned.
4. Testing: Use a double-source secondary injection test set to simulate varying phase angles. Verify that the “Sync OK” LED and output contacts only activate when the simulated sources are within the programmed window.
5. Commissioning: During first-run synchronization, use a synchroscope in parallel with the MAVS relay to visually confirm that the relay permits closing at the “12 o’clock” position.

Common Questions & Answers (Q&A)

Q: Does the MAVS02D1AB0751D automatically match the generator frequency? A: No. The MAVS is a check synchronizer, not an auto synchronizer. It only permits the close command when the conditions are already met; it does not send speed-up or slow-down pulses to the governor.

Q: What happens if the auxiliary DC power fails? A: The relay is designed to be “fail-safe.” If auxiliary power is lost, the output contacts remain open, preventing the circuit breaker from closing.

Q: Can this relay be used for both 50Hz and 60Hz systems? A: Yes, the MAVS02 series is typically designed to operate across both standard frequencies, though you should verify the specific voltage rating on the nameplate.

 

Explore More Synchronization & Protection Parts

For expert technical support and to source the MAVS02D1AB0751D along with other legacy GEC Alsthom and Alstom components, visit our online technical catalog.

 

Recommended Similar Models

1. MAVS01 – A simplified version of the check synchronizer for basic applications.
2. SKD / SKE – Legacy GEC Measurements synchronizing relays found in older switchgear.
3. MiCOM P847 – A modern numerical phasor measurement and synchronizing relay.
4. KVGC – An Alstom voltage and frequency regulating relay often used alongside the MAVS.
5. MVTT – A voltage-controlled overcurrent relay for generator backup protection.