Table of Contents
GEI-100728A
Mark* VIe Controls
System Redundancy Options
Instruction Guide
These instructions do not purport to cover all details or variations in equipment, nor to provide for every possible
contingency to be met during installation, operation, and maintenance. The information is supplied for informational
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Revised: Aug 2014
Issued: May 2008
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Table of Contents
Related Manuals for GE Mark VIe
Summary of Contents for GE Mark VIe
- Page 1 It is understood that GE may make changes, modifications, or improvements to the equipment referenced herein or to the document itself at any time. This document is intended for trained personnel familiar with the GE products referenced herein.
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Page 2: Table Of Contents
8 Digital Bus Reliability ..........................17 8.1 FOUNDATION Fieldbus........................17 8.2 PROFIBUS DP-V0 and DP-V1, Class 1 Masters..................17 8.3 HART Communications ......................... 17 8.4 CANopen Communications ........................17 9 Relative Reliability ............................. 18 GEI-100728A Mark VIe Controls System Redundancy Options Public Information... -
Page 3: Introduction
1 Introduction Control redundancy is used to improve the availability of the plant’s process. Its implementation varies with each application and the criticality of the process to the plant’s revenue. The premise of redundancy is that all control equipment has a mean-time-between-failure (MTBF) that can be compensated for with redundancy, so that the mean-time-between- forced-outage (MTBFO) of the entire system is better than the MTBF of the individual components. -
Page 4: Basic Redundancy Options
1, 2, or 3 Field Sensors Internal Power Supplies 1 or 2 Input Redundancy - Local Processors 1 or 2 per I/O Module Input Redundancy - Local Processors 1 or 3 per I/O Module GEI-100728A Mark VIe Controls System Redundancy Options Public Information... - Page 5 • • Typical Mark VIe Architecture Instruction Guide GEI-100728A Public Information...
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Page 6: Power Redundancy
V dc wetting voltage is needed for contact inputs or field solenoids, it can be provided directly from the station battery or from redundant 230 V ac to 125 V dc converters in the control. Diagnostics monitor power sources and power supplies for fault detection and to enable online repair. GEI-100728A Mark VIe Controls System Redundancy Options Public Information... -
Page 7: Controller
I/O electronics that interface with field devices. In a Mark VIe control system, IONET provides communication between the main processor(s) in the controller(s) and the local processors in the I/O packs that are located on the I/O modules. This communication architecture is a star configuration with the network switch(s) in the middle. -
Page 8: O Redundancy
An example of this configuration is in a heat recovery steam generator (HRSG) control that has minimal critical I/O except for the drum level. Triple redundant sensors can be added just for the drum level control to optimize system availability for the least cost. GEI-100728A Mark VIe Controls System Redundancy Options Public Information... - Page 9 Data outputs from dual redundant controllers are normally implemented with each controller sending its signal to its switch and each switch forwarding the signal to one of the two ports on an I/O pack on an I/O module. The pack uses the first healthy reference that it sees and continues to use it until it is not available or the pack determines that the signal is unhealthy.
- Page 10 Other considerations are whether the relays are sealed for hazardous locations, leakage current in the case of solid-state relays, suppression for solenoid applications and so forth. GEI-100728A Mark VIe Controls System Redundancy Options Public Information...
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Page 11: Triple Modular Redundancy
I/O modules on a common IONET to simplify operations and maintenance. When sharing I/O, the controllers from the Mark VIe and Mark VIeS can read inputs from all I/O modules, but write outputs only to their own I/O modules. - Page 12 Tolerance (SIFT). Its significance is that application software in each of the three control sections performs the voting rather than a single hardware voter that would compromise reliability by introducing a potential single point failure. GEI-100728A Mark VIe Controls System Redundancy Options Public Information...
- Page 13 Instruction Guide GEI-100728A Public Information...
- Page 14 This is hardware voting of the current outputs at the control valves. Standard GE triple redundant control systems are highly fault tolerant but not devoid of single point failures. As an example, I/O packs are mounted on I/O modules with passive components and high corresponding MTBF. Some applications, such as nuclear, require no single point failures.
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Page 15: Tripping Reliability
7 Tripping Reliability Simpl ex Simp lex Non- Redun dant Non- Red undan t Dual Redu ndan t Dual Red und ant Con troll er Contr ol ler Control ler Contr oller Contr ol Control Con trol Co ntrol V al ves Valve s Va lves Valves... - Page 16 Functionality for the backup protection system is application-specific and subject to the safety requirements dictated by code and/or GE design practices for specific turbine types. In general, it complies with most industry standards. It is separate and independent from the primary protection, with more functionality than required by most codes. As an example, ANSI/API-670 requirements for overspeed protection are written for an (one) independent, triple redundant system.
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Page 17: Digital Bus Reliability
8 Digital Bus Reliability In addition to the variety of classic Mark VIe I/O modules, additional I/O modules are available for digital busses such as Fieldbus™, PROFIBUS ® , HART ® , and CANopen ® . These modules share a common design with other I/O OUNDATION modules consisting of a local processor that communicates on the IONET to switches and then to the controllers. -
Page 18: Relative Reliability
Improving the quality of the devices and adding redundancy will help. Two surveys of GE turbine control installations indicated that field devices and wiring contributed to 57% and 69% of forced outages. Redundancy was applied to both the field devices and the electronics at these sites to mitigate the overall control system forced outages. - Page 19 Public Information...