The GEC Alsthom MCGG62F1CB0753D is a sophisticated digital protection relay from the acclaimed MCGG family. Designed for the protection of electrical power systems against overcurrent and earth faults, this relay combines the reliability of static technology with the flexibility of digital settings. It is widely used in distribution networks, industrial plants, and power stations to ensure the safety of transformers, motors, and feeders by rapidly isolating faults.

 

Product Technical Description

The MCGG62 is a three-phase overcurrent and earth fault relay. It utilizes high-accuracy analog-to-digital conversion to monitor line currents and compares them against user-defined characteristic curves. The “F1CB” designation refers to the specific hardware configuration, including the input current rating and the available time-delay characteristics (such as IDMT – Inverse Definite Minimum Time). The relay is housed in a draw-out case (typically a size 6 or 8 Midos case), which allows for easy testing and maintenance without disturbing the permanent wiring.

 

Product Datasheet & Parameters

• Model Number: MCGG62F1CB0753D
• Relay Type: 3-Phase Overcurrent + Earth Fault
• Series: MCGG (Midos range)
• Rated Current (In): 1A or 5A (Dual rated / Selectable)
• Rated Frequency: 50Hz / 60Hz
• Auxiliary Voltage: 24V – 125V DC or 110V – 250V AC/DC (Model dependent)
• Characteristic Curves: Standard IDMT (SI, VI, EI) and Definite Time
• Setting Range: 0.05 to 2.4 x In for overcurrent; 0.05 to 0.8 x In for earth fault
• Output Contacts: Multiple programmable changeover contacts (Trip/Alarm)
• Enclosure: Midos size 6 or 8 draw-out case

 

Country of Origin

This protection relay was manufactured by GEC Alsthom (now part of the GE / Alstom Grid heritage) in the United Kingdom (UK) or France.

 

Application Fields

• Substation Protection: Primary protection for incoming and outgoing feeders.
• Transformer Protection: Detection of external phase-to-phase and phase-to-earth faults.
• Industrial Plants: Protecting large AC motors and internal power distribution grids.
• Generator Sets: Backup overcurrent protection for small to medium generators.
• Marine & Offshore: Power management and circuit protection on vessels and platforms.

Product Usage Instructions

Before commissioning the MCGG62, ensure the CT (Current Transformer) ratios are correctly matched to the relay’s rated input. The relay settings are adjusted via the front panel potentiometers or DIP switches located behind the transparent cover. To test the relay, the draw-out module can be partially withdrawn to access the test terminals using a Midos test plug. Ensure the auxiliary power supply is within the specified range before energizing. During operation, the “Health” LED should remain lit, while “Trip” flags will indicate the nature of the fault (Phase A, B, C, or Earth).

 

Common Questions & Answers (Q&A)

Q: Can I change the time-delay curve on this relay? A: Yes, the MCGG series allows you to select between Standard Inverse (SI), Very Inverse (VI), and Extremely Inverse (EI) curves using the internal selectors to match your coordination requirements.

Q: What does it mean if the relay is “Draw-out”? A: It means the active electronic part of the relay can be removed from its outer case without disconnecting the wires at the back. The case contains automatic CT shorting links to prevent dangerous open-circuit voltages when the relay is removed.

Q: Is the MCGG62 compatible with modern SCADA systems? A: While primarily a standalone protective device, status contacts can be wired into a PLC or RTU. For digital communication, newer versions like the MiCOM series are typically used.

Q: How do I reset a trip flag after a fault? A: Once the fault is cleared, the mechanical or LED indicators can be reset using the “Reset” button located on the front face of the relay.

 

Similar Model Recommendations

1. GEC Alsthom MCGG22F1CB0753D
2. GEC Alsthom MCGG42F1CB0753D
3. GEC Alsthom METI series (Earth fault only)
4. Alstom MiCOM P12x series (Modern digital equivalent)
5. GEC Alsthom MCHN series (Differential protection)