Alstom MCAG User Manual

MCAG/MFAC
User Guide
Application of High Impedance Relays
Publication Reference: R6136C
R6136C © 2012. ALSTOM, the ALSTOM logo and any alternative version thereof are trademarks and service marks of ALSTOM. The other names mentioned,
registered or not, are the property of their respective companies. The technical and other data contained in this document is provided for information only. Neither
ALSTOM, its officers or employees accept responsibility for, or should be taken as making any representation or warranty (whether express or implied), as to the
accuracy or completeness of such data or the achievement of any projected performance criteria where these are indicated. ALSTOM reserves the right to revise or
change this data at any time without further notice.
GRID

Alstom MCAG Specifications

General

Manufacturer	Alstom
Mounting	Panel Mounted
Rated Current	1A or 5A
Frequency	50/60 Hz
Operating Time	Depends on settings

Summary

The Application of High Impedance Relays

Introduction

Explains the principle of high impedance differential protection and its application.

Relay Types and Application

The MCAG14/34

Details the MCAG14/34 electromechanical current relay and its characteristics.

The MCTI14/34

Describes the MCTI14/34 electronic instantaneous overcurrent relay for protection.

Applying the MCAG14/34 & MCT114/34

Provides guidance on setting relay current and stabilising resistors for applications.

Use of Metrosil Non-Linear Resistors

Application of the MFAC14/34 Relay

Typical Setting Examples

Restricted earth fault protection using MFAC14

Illustrates setting examples for MFAC14 in transformer restricted earth fault protection.

Restricted earth fault protection using MCAG14

Demonstrates setting examples for MCAG14 in transformer restricted earth fault protection.

Typical Setting Examples - Continued

Restricted earth fault protection using MCT114

Shows setting examples for MCT114 in transformer restricted earth fault protection.

Generator Winding Differential Protection

Using MCAG34

Details applying MCAG34 for generator winding differential protection, considering CT kneepoint voltage.