Type 87M Machine Differential Relay Errata

This document provides corrections and clarifications to the Type 87M Instruction Booklet IB 7.6.1.7-1, Issue C, specifically regarding the reactor impedance values in 219M three-phase and 419M single-phase differential relay units. It includes updated tables specifying reactor impedance thresholds (over 400 ohms or over 1000 ohms) and instructions for identifying reactor types based on catalog numbers and physical descriptions.