The GEC Alsthom MVAA11B1BA0783C is a high-performance, attracted-armature auxiliary relay from the robust MVAA series. Originally developed by GEC Alsthom (a legacy brand of Alstom, AREVA, and Schneider Electric), this relay is a fundamental building block in substation control and protection logic. It is designed to provide contact multiplication, electrical isolation, and signal interlocking. The MVAA series is prized for its high speed, reliability, and low power consumption, making it ideal for critical utility and industrial power systems.

Technical Description & Parameters

The MVAA11B1BA0783C is a voltage-operated relay engineered for continuous duty in demanding environments.

• Model Number: MVAA11B1BA0783C
• Relay Type: Single-Pole (MVAA11) Auxiliary Relay.
• Operating Voltage (Un): 110/125V DC (indicated by the ‘BA’ and ‘0783’ codes).
• Configuration: 2 Normally Open (NO) and 2 Normally Closed (NC) contacts (Standard 2/2 arrangement).
• Reset Type: Self-Reset (The relay returns to its original state when the coil is de-energized).
• Operating Time: Fast-acting (typically <15ms to <25ms).
• Contact Rating: Heavy-duty silver-alloy contacts capable of 5A continuous and high-inductive breaking capacity.
• Mounting: Standard draw-out case (Size 2).

 

Product Technical Description

The MVAA11 utilize a high-efficiency solenoid and a balanced armature. When the rated DC voltage is applied to the coil, the magnetic field pulls the armature, which mechanically drives the contact assembly. The “11” designation refers to the specific internal assembly and contact count. The “C” suffix denotes a specific hardware revision that includes enhanced insulation and transient protection for the coil. Because it is a self-resetting model, it is frequently used as a “repeater” relay to pass signals between different voltage levels or to isolate sensitive electronic circuits from high-power trip coils.

 

Product Datasheet Essentials

This relay features a transparent front cover, allowing for easy visual inspection of the contact state and mechanical health. The draw-out design is a key feature; the relay module can be pulled from its case, and the case automatically shorts any necessary circuits to maintain system integrity. The MVAA11B1BA0783C is fully tropicalized to withstand humidity and is rated for a wide operating temperature range (–10°C to +55°C). It requires no regular maintenance and is designed for a mechanical life of over 100,000 operations.

 

Country of Origin

United Kingdom / France (GEC Alsthom Protection & Control)

 

Application Fields

The MVAA series is utilized in various protection and control schemes:

• Contact Multiplication: Using one signal to trigger multiple independent circuits (e.g., Alarms, SCADA, and Interlocks).
• Electrical Isolation: Separating a 110V DC control circuit from a 24V DC PLC input.
• Logic Schemes: Providing “And/Or” logic in circuit breaker interlocking and auto-reclosure systems.
• Remote Signaling: Driving remote lamps or annunciators in a central control room.

 

Product Usage Instructions

1. Installation: Insert the relay module into the draw-out case. Verify that the coil voltage (110/125V DC) matches your station battery voltage.
2. Wiring: Connect the initiating signal to the coil terminals. Wire the NO/NC contacts into the logic or signaling loops as required by your schematic.
3. Testing: Manually actuate the armature (if accessible) or apply rated DC voltage to the coil to verify the contacts switch correctly.
4. Polarity: For DC models, ensure the polarity of the coil wiring matches the labeling on the rear terminals if a suppression diode is fitted.
5. Inspection: Periodically check the silver contacts for signs of excessive pitting or carbon buildup if the relay is switching highly inductive loads.

 

Common Questions & Answers (Q&A)

Q: What is the difference between MVAA (Auxiliary) and MVAJ (Tripping) relays? A: The MVAA is a general-purpose auxiliary relay (often self-reset), while the MVAJ is a specialized high-speed tripping relay (often hand or electrical reset) designed specifically to handle circuit breaker trip coils.

Q: Can I use this relay for AC control circuits? A: No, the MVAA11B1BA0783C is specifically wound for DC voltage. Using it on an AC circuit will cause the relay to vibrate (hum) and will likely overheat the coil.

Q: How do I know if the relay has operated? A: Since this is a self-resetting model, there is no mechanical flag. You can verify operation by observing the movement of the armature through the clear front cover or by monitoring the state of the output contacts.

 

Explore More Substation Logic Hardware

For technical support and to source the MVAA11B1BA0783C along with other GEC Alsthom legacy spare parts, visit our online technical catalog.

 

Recommended Similar Models

1. MVAA21 – A dual-element version for more complex signal multiplication.
2. MVAJ11 – A high-speed tripping relay for circuit breaker control.
3. MVAW – A specialized auxiliary relay with definite time delays.
4. VAA – The legacy predecessor to the MVAA series found in older substations.
5. KVAJ – A modern numerical relay that can perform multiple auxiliary functions.