Generator Protection

Multilin 889

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The Multilin 889 relay, a member of the Multilin 8 Series protective relay platform, has been designed for the protection, control, monitoring and management generators and in-zone transformers used in both industrial and utilities applications.

The Multilin 889 provides advanced, high-speed protection, extensively customizable programmable logic, and flexible configuration capabilities, to maximize the operational performance and life of critical generators.

Equipped with the latest in advanced communications, the Multilin 8 Series supports IEC 61850 Edition 2 ensuring simplified device integration and dual communication ports with IEC 62439/PRP, enabling users to achieve zero latency in communications for high reliability network architectures, ensuring complete asset monitoring and control.

Key Benefits
  • Enhanced generator protection algorithms provide sub-cycle differential protection, ensuring faster fault clearing times for reduced generator damage

  • Dedicated generator monitoring and control functions providing mission critical operational data to enable a pro-active maintenance approach

  • Additional overall generator-transformer differential (87O) providing additional back-up protection

  • Advanced differential protection for both generator and in-zone transformer

  • Industry standard cyber security tools such as AAA, Radius, RBAC and Syslog enabling NERC/CIP requirements

  • Draw-out design simplifies testing and increases process uptime

  • Optional Wi-Fi minimizes system configuration and facilitates safe relay programming and diagnostic retrieval

  • Comprehensive protection from small to large generators

  • Industrial or utility power generation

  • Co-generation and renewable generation applications

  • Unit Transformer Protection applications

Multilin 889 Overview

The 889 has been designed for the protection, control, and management of generators and associated unit transformers in critical utility and industrial applications.

Generator Stator Differential Protection

The 889 utilizes high-speed dual slope differential protection for detecting and clearing of stator phase faults. Advanced CT saturation detection algorithms maintain immunity to saturation conditions that may be caused due to external disturbances through the use of a directional check that provides additional supervision and ensures the fault is internal to the generator before triggering it to trip.

Overall Generator & Transformer Differential Protection

The 889 can provide overall generator and transformer differential protection (87O). It covers the protection zones from the generator neutral to the GSU (Generator Step-Up) transformer’s High Voltage (HV) winding. This additional protection element provides backup to both Generator Stator Differential (87G) and a dedicated transformer differential in a transformer relay (i.e.: Multilin 845 Transformer Protection System). The 889 with this Generator-Transformer Differential protection supports transformer setup, provides enhanced protection security by including both restrained and unrestrained (instantaneous) differential protection.

100% Stator Ground

100% stator ground fault protection is provided through an overvoltage element and an adaptive voltage differential feature responding to the unbalance of the third harmonic at the machine terminals and at the neutral point. The 889 compares the machine neutral voltage and ground current to determine if ground directional faults are within or outside the generator.