The GEC Alsthom MCGG82H1CB0753D is a highly versatile, microprocessor-based overcurrent and earth fault relay from the esteemed MCGG family. This relay was a pioneer in transitioning from electromechanical to digital protection, offering significantly higher precision and a wider range of time-current characteristics. The MCGG82 model is a dual-element unit, typically configured for two-phase overcurrent or a combination of overcurrent and earth fault protection, providing a robust defense for transformers, motors, and distribution feeders.

 

Product Datasheet & Technical Specifications

The “82” series represents the dual-measurement configuration within the MCGG range:

• Model Number: MCGG82H1CB0753D
• Relay Type: Microprocessor Time-Overcurrent Relay
• Current Inputs: Selectable 1A or 5A secondary ratings
• Time Characteristics: Supports multiple IDMT (Inverse Definite Minimum Time) curves including Standard Inverse, Very Inverse, and Extremely Inverse, plus Definite Time settings.
• Setting Range: Wide adjustment range via front-panel DIP switches (e.g., 0.05 to 2.4 times rated current).
• Auxiliary Supply: 110V to 125V DC (indicated by the ‘H’ voltage code).
• Case Size: Size 4 modular drawout case (allows for easy removal without disturbing wiring).
• Contacts: High-duty trip and alarm contacts with mechanical flag indicators.

Country of Origin

This protection device was engineered and manufactured in the United Kingdom (UK) at the Stafford facility, maintaining the high standards of the GEC Alsthom (later Alstom/AREVA) protection and control division.

 

Application Fields

The MCGG82H1CB0753D is a flexible solution for various power system topologies:

• Feeder Protection: Providing primary or back-up protection for medium voltage radial and ring mains.
• Transformer Protection: Guarding against phase-to-phase and phase-to-earth faults on both primary and secondary sides.
• Motor Protection: Handling stalled rotor and heavy overload conditions in large industrial motors.
• Capacitor Bank Protection: Monitoring for overcurrent conditions in power factor correction units.
• Industrial Distribution: Protecting critical electrical infrastructure in refineries, mines, and steel mills.

 

Product Instructions & Technical Notes

When commissioning the GEC Alsthom MCGG82H1CB0753D, verify that the auxiliary supply matches the ‘H’ code (110-125VDC) to avoid damaging the internal power supply module. The relay features a drawout design; ensure the “shorting switches” in the case are functional before removing the relay to prevent high-voltage arcing in the current transformer circuits. Settings are adjusted via DIP switches behind the front transparent cover—ensure that the “TMS” (Time Multiplier Setting) is accurately calculated based on the coordination study of your specific power network to ensure selective tripping.

 

Q&A – Frequently Asked Questions

Q1: What is the difference between an MCGG22 and an MCGG82? A: The MCGG22 is a single-phase/single-element unit, whereas the MCGG82 is a dual-element unit, allowing for two independent measurements (such as two phases, or one phase and one earth fault) within a single housing.

Q2: How do I change the tripping curve? A: The curve type (Standard, Very, or Extremely Inverse) is selected using the internal DIP switches. You must refer to the relay’s manual to find the specific switch positions for the desired characteristic.

Q3: Does this relay require periodic calibration? A: Being a digital relay, it is much more stable than electromechanical types. However, annual functional testing via secondary injection is recommended to verify the timing accuracy and contact operation.

Q4: What does the “753D” suffix refer to? A: This is a factory configuration code that specifies the hardware revision, specific language labels, and contact arrangement (Normally Open/Normally Closed) of the output relays.

 

Similar Model Recommendations

1. GEC Alsthom MCGG22 (Single-phase overcurrent relay)
2. GEC Alsthom MCGG42 (Three-phase overcurrent relay)
3. GEC Alsthom METI (Dedicated Earth Fault Relay)
4. Alstom MiCOM P12x series (The modern digital successor to the MCGG series)
5. GEC Alsthom MVAA (Auxiliary tripping relay often used alongside MCGG units)