GE 889REF-AB-280 Generator Protection System

GE 889REF-AB-280 Generator Protection System

OVERVIEW

The Multilin™ 889 Generator Protection System, a member of the Multilin 8 Series protection  relay platform, has been designed for the protection, control, and management of generators and  associated unit transformers in critical utility and industrial applications. The 889 goes beyond asset protection providing power system engineers with the data, measurement  accuracy, and visibility needed for comprehensive generator management. These advanced asset  monitoring capabilities provides engineers with the ability to make informed, proactive decisions that  enable planned maintenance activities reducing costs associated with pre- and post-fault analysis,  equipment damage, and unplanned or extended downtime.  With a focus on connectivity and security, the 889 supports the latest in communications technologies  and protocols including IEC 61850 Edition 2, OPC-UA, and IEC 62439/PRP, and provides advanced,  industry standard, cybersecurity tools, ensuring simplified and secure device integration into new or  existing SCADA or DCS systems.

Innovative  Technology & Design

• Proven algorithms delivering sub-cycle and  reliable differential protection 

• Continuous monitoring and event driven  diagnostics for a wide range of generator  applications 

• Patented environmental monitoring &  diagnostics 

• Advanced, flexible and embedded  communications: IEC® 61850 Ed2, OPC-UA, IEC 62439/PRP, Modbus® RTU & TCP/IP,  DNP3.0, IEC 60870-5-104 

• Single setup and configuration across the  8 Series platform 

• Field swappable power supply 

• Enhanced relay draw-out construction 

• Elimination of electrolytic capacitors

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 generator diagnosis, comprehensive asset monitoring and high-end fault and  disturbance recording, simplifies pre- and post-fault analysis 

• Advanced cyber security features including AAA, Radius, RBAC and Syslog enabling NERC/CIP  requirements 

• Low insertion force, draw-out design simplifying testing, commissioning, and maintenance for  increased process uptime 

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

• Patented environmental monitoring, providing visibility to changes in environmental conditions  that can affect relay life

Generator Stator Differential

The 889 provides fault clearing operation at up to sub-cycle speed, by  utilizing a 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, additional supervision is provided to ensure the fault is internal  to the generator before triggering it to trip. This sub-cycle operation  translates to less burning, and hence low carbon dissipation and thermal  stress on insulation. This also enables root cause analysis during diagnosis/ maintenance of the winding (sever longer duration faults burns-out all the  evidence and make root cause analysis extremely difficult or sometimes  impossible).

Overall Generator & Transformer Differential Protection

The 889 provides overall generator and transformer differential protection  (87O). It covers the protection zones from the generator neutral to the  Generator Step-Up (GSU) Transformer’s High Voltage (HV) winding.  For mid to large-size machines, the typical protection philosophy and  architecture is to implement a dedicated transformer protection device  along with a single function differential relay to provide the overall  differential protection between the transformer and the generator. With  support for 3 sets of phase CT inputs, the 889 can replace the single  function device, providing the necessary overall differential protection  with the added benefit of protection redundancy for both the Transformer  and the Generator, when there is no tapping between the generator and  GSU or unit transformer.

100% Stator Ground Fault Protection

The 889 provides 100% Stator Ground Fault Protection for High  Resistance Grounded System (HRG), Low Resistance Grounded (LRG)  or Hybrid Grounded Systems. For HRG systems the 889 employes a  unique combination of Auxiliary Overvoltage and 3rd Harmonic Neutral  Undervoltage protection elements to provide secure, reliable protection  of the stator winding. With this function the 3rd harmonic neutral voltage  variations do not need to be considered, simplifying the settings and  configuration process.  

For LRG systems with parallel machines, the 889 provides ground fault  coordination ensuring only the faulted generator is islanded. In Hybrid  Grounded Systems, the 889 provides fast, dynamic switching from  low-z to high-z when an internal generator fault is detected, reducing  potential damage to the generator and eliminating the need for additional  protection devices.

Sensitive Directional Power

The 889 provides low forward power and reverse power elements to  prevent generator motoring that can cause damage the prime mover.  Independent settings for power pickup levels and operational delays are  available for both alarming and tripping of each element. The 889 directional power element responds to three-phase directional  power and is designed for reverse power (32REV) and low forward power  (32FWD) applications for interconnections involving co-generation.