Description

GE / Alstom MCAG High Impedance Bus Differential Relay

GE MCAG busbar relay provides high-speed differential protection for various types of power system plants Including generators, reactors, busbars, motors and the individual windings of power transformers. The relays provide current-calibrated busbar differential and have an attracted armature design with simple and robust construction.

The MCAG relay, used with a stabilizing resistor, is designed for applications where sensitive settings with stability on heavy through faults are required, and is recommended for balanced and restricted earth fault, bus-zone and certain forms of differential protection for generators, auto-transformers, reactors and motors. The relay operates
as a high impedance unit protection scheme.

GE MCAG busbar relay Key features:

• High thermal withstand – improved when used with the stabilising resistor
• Long service history, over 43,000 delivered since 1984
• Design pedigree coming from over a million auxiliary relays in-service

Key benefits:
• High stability during through faults Operation is fast and reliable (25ms at 5 x setting)
• Easy integration into 4U height MIDOS rack schemes
• Highly-tuned to the fundamental to prevent spurious operation

Main characteristics:
• 3 element relay supplied in a 30TE (size 6 inch) case
• Supplied with a stabilising resistor
• Optional Metrosil available to limit CT saturation voltage
• Use with MVTP where scheme buswire supervision is required

Application

When circulating current protection schemes are subjected to heavy through faults, the sudden and often symmetrical growth in the system current can cause the protective current transformers to approach or even reach saturation level. This may result in a high unbalancing current due to the variations in the magnetizing characteristics of the current transformers. To ensure stability under these conditions, it is common practice to use a
high impedance relay, set to operate at a voltage slightly higher than that developed by the current transformers under maximum external fault conditions.

We offer GE’s century long tradition of power system innovation. From generators to transmission lines, to motors and beyond, we ensure dependable, safe power worldwide. GE offers a wide range of single function and auxiliary relays, along with a portfolio of accessories, to support high performing and reliable protection and control systems. To explore the GE portfolio with us click here GE numerical Relays !