The GEC Alsthom MVTD12C1CD0751E is a high-reliability, solid-state time-delay relay belonging to the specialized MVTD series. Manufactured by GEC Alsthom (a legacy brand of Alstom, now part of the Schneider Electric and GE ecosystems), this relay is designed to provide precise, adjustable time delays for protection and control schemes in medium and high-voltage substations. The MVTD is frequently used for “Definite Time” overcurrent protection or as a critical timing element in complex logic circuits, such as auto-reclose schemes or breaker failure protection.

Technical Description & Parameters

The MVTD12C1CD0751E features an electronic timing circuit that offers significantly better accuracy and repeatability than older pneumatic or thermal timing relays.

• Model Number: MVTD12C1CD0751E
• Relay Type: Definite Time Delay Relay (Single or Multi-Pole configuration)
• Time Range: Typically adjustable from 0.05s to several seconds (refer to front dial for specific range)
• Input Rating: Standard 1A or 5A CT secondary inputs (depending on internal taps)
• Auxiliary Power: 110-125V DC (indicated by the “CD” code in the model string)
• Output Contacts: High-duty silver alloy contacts (Normally Open/Normally Closed configurations)
• Reset Time: Fast reset (<50ms) to ensure readiness for subsequent faults
• Mounting: Standard draw-out case for easy maintenance

 

Product Datasheet Essentials

This relay provides a “Definite Time” characteristic, meaning it will trip after a set number of seconds regardless of the magnitude of the fault current, provided the current exceeds the pickup threshold. The “E” suffix refers to the specific case design and terminal arrangement. It includes a mechanical flag indicator that drops upon operation, allowing technicians to quickly identify which relay in a lineup has triggered an event. The electronic components are tropicalized and designed to withstand the high-transient environments of industrial power systems.

 

Country of Origin

United Kingdom / France (GEC Alsthom Protection & Control)

 

Application Fields

The MVTD series is a staple in various electrical infrastructure settings:

• Breaker Failure Protection: Providing the necessary “wait time” before tripping upstream breakers.
• Transformer Protection: Used as a backup time-delayed overcurrent element.
• Industrial Control: Managing sequence timing in large motor starting or load shedding schemes.
• Utility Substations: Coordination with distance relays or auto-reclosers to ensure system stability.

 

Product Usage Instructions

1. Installation: Slide the relay into its dedicated rack. The draw-out design allows you to remove the relay for testing without disconnecting the secondary wiring of the CTs (the case features automatic shorting bars).
2. Setting the Time: Use the front-panel potentiometers or thumbwheels to set the desired delay. Ensure the setting aligns with your system’s coordination study to prevent nuisance tripping.
3. Pickup Adjustment: If equipped with a current pickup adjustment, set the threshold at which the timer begins its countdown.
4. Testing: Perform a secondary injection test. Verify that the time from the application of current to the closing of the output contacts matches the dial setting within the specified tolerance (usually ±5%).

 

Common Questions & Answers (Q&A)

Q: What is the main difference between MVTD and MVTI relays? A: The MVTD is a Definite Time relay (constant delay), whereas the MVTI is an Inverse Time relay (the higher the current, the faster it trips).

Q: Can the MVTD12C1CD0751E be used without an auxiliary DC supply? A: Most versions of the MVTD require an auxiliary DC supply (the “CD” code) to power the internal electronic timing circuit and the output relays.

Q: Is it safe to pull the relay out while the system is live? A: Yes, the GEC Alsthom draw-out cases are designed with safety features that short-circuit the CT inputs when the relay is removed, preventing dangerous high-voltage peaks on the CT secondary.

 

Explore More Protection & Control Parts

For technical support and to source the MVTD12C1CD0751E along with other legacy GEC Alsthom protection components, visit our online catalog.

 

Recommended Similar Models

1. MVTD11 – A single-phase version for simpler timing requirements.
2. MVTI12 – The inverse-time counterpart for coordinated feeder protection.
3. MCGG22 – A modern digital overcurrent relay that can perform both definite and inverse timing.
4. METI – A basic definite-time overcurrent relay often found in older switchgear.
5. KCGG140 – A multi-function Alstom numerical relay used for comprehensive feeder management.