PLC

1,100 views

Published on

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
1,100
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
34
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

PLC

  1. 1. PLC System Presentation.doc 1/2/01 PROGRAMMABLE LOGIC CONTROLLERS AT JEFFERSON LAB Henry Robertson Safety Systems Group TJNAF/Jefferson Lab
  2. 2. PLC System Presentation.doc 1/2/01 USES OF PROGRAMMABLE LOGIC CONTROLLERS AT JEFFERSON LAB • Equipment Status • Process Control • Chemical Processing • Equipment Interlocks • Machine Protection • Smoke Detection • Gas Monitoring • Envelope Monitoring • Personnel Safety
  3. 3. PLC System Presentation.doc 1/2/01 USES OF PROGRAMMABLE LOGIC CONTROLLERS AT JEFFERSON LABChemical Processing Processing of Niobium Super conducting cavities uses a buffer chemical polish BCP Acids: Hydroflouric Phosphoric Nitric Chemical processing cabinet that is normally used for semiconductor wafer processing Built to the semi-conductor industry standard SEMI S93.02
  4. 4. PLC System Presentation.doc 1/2/01 USES OF PROGRAMMABLE LOGIC CONTROLLERS AT JEFFERSON LABGas Monitoring Experimental Hall B PLCs used for alarm functions System Part of Evaluated by Factory Mutual Corp. Oxygen Monitoring (for ODH) in CEBAF tunnels and halls Processor based Networked transmitters / sensors
  5. 5. PLC System Presentation.doc 1/2/01 USES OF PROGRAMMABLE LOGIC CONTROLLERS AT JEFFERSON LABMachine Protection Free Electron Laser Machine Protection System PLCs used for system set up and device monitoring Automatically detects FEL configuration and limits beam current to appropriate level
  6. 6. PLC System Presentation.doc 1/2/01 USES OF PROGRAMMABLE LOGIC CONTROLLERS AT JEFFERSON LABEnvelope Monitoring Beam Envelope Limit System (BELS) Used to ensure that nuclear physics accelerator remains within operations and safety envelope Allows beam operation close to envelope limits Measures beam power Redundant PLCs using voting arrangement on inputs
  7. 7. PLC System Presentation.doc 1/2/01 USES OF PROGRAMMABLE LOGIC CONTROLLERS AT JEFFERSON LABEnvelope Monitoring
  8. 8. PLC System Presentation.doc 1/2/01 USES OF PROGRAMMABLE LOGIC CONTROLLERS AT JEFFERSON LABEnvelope Monitoring Arc PLC Current FSD 2oo3 voting Beam Current Arc Current Arc PSS BCM Current PLC 2oo3 Voting
  9. 9. PLC System Presentation.doc 1/2/01 USING PLCS IN THE PERSONNEL SAFETY SYSTEMWhy Programmable Controllers? • Complexity – Much less complex than large relay based system • Modularity – Very flexible due to network architecture • Documentation – Virtually self-documenting • Resource limitations – Very space efficient and less manpower required to install • Cost and schedule – Up front material costs are similar, but savings on installation, maintenance, and troubleshooting increase rapidly as system size increases • Reliability – Industry and lab experience demonstrate PLCs comparable to relay system • Familiarity – Huge knowledge base in industry • Training – Short learning curve for hardware and programming • Troubleshooting – Ability to monitor every sensor speeds debug and repair
  10. 10. PLC System Presentation.doc 1/2/01 USING PLCS IN THE PERSONNEL SAFETY SYSTEM • Programmable Logic Controllers (PLC) used to emulate relay logic interlocks and provide device status • Special computers/software used for programming and status • Stringent programming procedure used • Rigorous testing procedures followed • Hardware and software changes tightly controlled • Proven high reliability and availability
  11. 11. PLC System Presentation.doc 1/2/01 PROGRAMMABLE LOGIC CONTROLLER SYSTEM • 2 independent PLC systems (A and B) • Each system consists of approximately 1000+ I/O points • System segmented into 6 physical areas for modularity • High speed network used for peer-to-peer communication • Fiber optic modems provide long distance networking and EMI isolation • Discrete monitoring of every sensor device • Discrete management of every control device
  12. 12. PLC System Presentation.doc 1/2/01 PROGRAMMABLE LOGIC CONTROLLER SYSTEM • Human Machine Interface (HMI) software allows standardized status screens • Secure stand-alone computer and software for programming logic • Throughput / response time < .5 seconds • High-density modules allow efficient use of rack space • “Soft” wiring requires only one person • Built-in diagnostics simplify trouble-shooting
  13. 13. PLC System Presentation.doc 1/2/01 TYPICAL PLC SYSTEM NETWORK (1 OF 2) Master Drop Master Drop w/ Local I/O w/ Local I/O Remote I/O Drop Program Display Peer-to-Peer Network Computer Computer Fiber Optic Modem Fiber Optic Fiber Optic Modem Fiber Optic Modem Master Drop Modem w/ Local I/O Master Drop w/ Local I/O Peer-to-Peer Network Master Drop Master Drop Master Drop w/ Local I/O w/ Local I/O w/ Local I/O Remote I/O Drop Hardwired Feedback
  14. 14. PLC System Presentation.doc 1/2/01 REDUNDANT PLC DIAGRAM System A Peer-to-Peer Network (1 million bits/sec) System A PLC Remote I/O Network (1.5 million bits/sec) Program Computer Master Drop Remote I/O Drop w/ Local I/O 24 VDC Device Display System B PLC 24 VDC Computer Master Drop w/ Local I/O Remote I/O Drop System B Peer-to-Peer Network Remote I/O Network (1 million bits/sec) (1.5 million bits/sec)
  15. 15. PLC System Presentation.doc 1/2/01 EXAMPLE OF REDUNDANT SAFETY INTERLOCK Sensor Status Input Isolation Module Main Processor Module Permissive Output Isolation Module PLC A Controlled Control Circuit Device Output Isolation Module Permissive Main Processor Module Input Isolation Module Status Sensor PLC B Sensor output must be +24 V to indicate safe. PLC output must be +24 V to energize the controlled device. Isolation is provided by relays, opto-couplers, or both.
  16. 16. PLC System Presentation.doc 1/2/01 MASTER PLC DROP WITH LOCAL I/O
  17. 17. PLC System Presentation.doc 1/2/01 SEGMENTATION • Site is segmented into 6 physical areas Injector/North Linac, South Linac, Beam Switchyard, Hall A, Hall B, Hall C • PLC Masters are located in each physical area (some areas include Remote I/O drops) • Allows separate maintenance and auditing of each segment • Allows operation and test of the accelerator in logical pieces • Each segment can operate independently up to the point where operation of a device within one area may present a hazard in another area • At that point the areas must agree that it is safe to operate the hazardous device • Inter-segment communication handled with hardwired handshake
  18. 18. PLC System Presentation.doc 1/2/01 In je c to r/N o rth L in a c S h ie ld Segm ent W a lls W est E ast H a ll A Segm ent H a ll B Segm ent BSY Beam S o u th L in a c H a ll C S w itc h y a rd Segm ent Segm ent Segm ent Hall A BSY Hall B Injector Gun On? Hall C North Linac South Linac PSS Segment Intercommunication
  19. 19. PLC System Presentation.doc 1/2/01 HMI / SYSTEM MONITORINGFour computers are used in the monitoring of the PSS • Display computer - operates as the safety system operator’s display • Development Computer - operates as the PSS technician’s remote display • Program Computer - programming, diagnostic, and performance monitoring of the PLC logic • X-terminal - passes PSS status to the JLAB instrumentation and control system, EPICS
  20. 20. PLC System Presentation.doc 1/2/01 DISPLAY / DEVELOPMENT COMPUTERS • Local and remote status screens • Trouble-shooting screens • Flexible interface for easily customized screens • Includes security, alarming, and event logging functions • Uses network to monitor status of each area • No critical information, e.g. interlock logic, is transferred over the network • Configured as a read-only device
  21. 21. PLC System Presentation.doc 1/2/01 DISPLAY COMPUTER – SITE SCREEN
  22. 22. PLC System Presentation.doc 1/2/01 STATUS SCREENS FOR NORTH LINAC SEGMENT
  23. 23. PLC System Presentation.doc 1/2/01 STATUS SCREENS FOR NORTH LINAC SEGMENT
  24. 24. PLC System Presentation.doc 1/2/01 STATUS ICONSInputs are grouped by functionThe PSS system A and System B inputs are shown separately as a circular icon. Radiation Monitors PLC A or B A B Device Number RM 201 RM 202 Status IconA GREEN icon means the device is in the OK or safe condition.A RED icon means the device is in the fault or unsafe condition.
  25. 25. PLC System Presentation.doc 1/2/01 TROUBLE-SHOOTING SCREEN
  26. 26. PLC System Presentation.doc 1/2/01 PLC PROGRAMMING • PLCs are programmed by two independent programmers • Information on implementation and algorithms are not shared • Each person writes the program to conform to a general functional specification of how the logic system should behave • Each PSS segment has a general logic specification • The specification gives a functional and logical description of the PLC logic for the area • The specification is careful to avoid detailed algorithms or suggested implementations • This allows the greatest degree of freedom in the actual implementation of the logic • The logic spec defines two types of logic 1. state logic, e.g., Restricted Access, Sweep, Controlled Access, etc. 2. device logic - defines the requirements for the PSS interface with a given device
  27. 27. PLC System Presentation.doc 1/2/01 EXAMPLE OF THE SPEC FOR STATE LOGIC Beam Permit = [ Doors and Gates & / Crash & Exchange Key IN & Sweep Complete & Radiation Monitor OK & High Voltage Ready & / Laser Bypass & External Systems Ready & Chain Intact & ( Beam Permit Key Switch Timer OR Beam Permit Mode ) ]
  28. 28. PLC System Presentation.doc 1/2/01 EXAMPLE OF THE SPEC FOR DEVICE LOGIC RS(n) Operational = [ ( ( Sweep Mode & RS(n) Set Interlock ) OR RS(n) Operational ) & / RS(n) Crash & RS(n-1) Operational ]Each programmer decides how to implement the logic in the context of the overall requirements forthe programThe two implementations are rarely immediately recognizable as being functionally equivalent
  29. 29. PLC System Presentation.doc 1/2/01 PROGRAMMING APPLICATION WITH TYPICAL LADDER LOGIC DIAGRAM
  30. 30. PLC System Presentation.doc 1/2/01 DOCUMENTATION • Virtually self-documenting • Ladder Logic diagrams with common name descriptors • “Traffic Cop” system configuration listings • Detailed listings of all I/O used including descriptions • Processor and network configuration details
  31. 31. PLC System Presentation.doc 1/2/01 SAFETY SYSTEM CERTIFICATION • Adheres to Jefferson Lab Certification Procedure • Full Certification of the complete PSS is done semi-annually • An Operations Crew Chief serves as the Test Director • Full Certification required for: If any part of the PLC interlock logic has been changed If the PLC CPU has been removed from the crate • Partial Certification required for: Required for any device or subsystem which has been modified Modification includes temporary disconnection and/or replacement. Must include all components affected by or connected to the device/system replaced
  32. 32. PLC System Presentation.doc 1/2/01 SAFETY SYSTEMS GROUP CERTIFICATION PROCEDURES • Must follow Static and Functional test procedures exactly • Static test of all PSS inputs and outputs • Functional test of the operation of the PSS logic • Tests the separate response of systems A and B to ensure that each responds independently
  33. 33. PLC System Presentation.doc 1/2/01 SAFETY SYSTEMS GROUP CERTIFICATION PROCEDURESTypical static tests: • Radiation Monitor Test Tests dose rate alarm function of CARM Tests bypass function of CARMs located in tunnel or endstations • Interface Chassis Test Tests Power Permit Off/Safe Interlock Ready input • Segment Interface Test Tests interdependence of beam states Tests injector logicTypical functional test: • Tests special operating modes or combinations of device states • Tests actual ability of PSS to shut off Gun and other power supplies
  34. 34. PLC System Presentation.doc 1/2/01 CONFIGURATION CONTROLJefferson Lab Configuration Control Policy • Sets baseline configuration • Explains change control procedure • Describes system classification levels • Sets up configuration accounting • Defines special rules for hardware and software repairs • Classifies systems and devices by level of control • Includes required forms and process instructions
  35. 35. PLC System Presentation.doc 1/2/01 CONFIGURATION CONTROLInstallation considerations: • Isolation • Protection • LabelingSecurity measures: • Password access to all computers • Secured Memory Protect key
  36. 36. PLC System Presentation.doc 1/2/01 RELIABILITY AND AVAILABILITYReliabilityYears of operation 10 1/2Faults causing hazard to personnel (fail unsafe) 0Faults caused by software 0Hardware failures: • Power Supply - 2 • CPU - 0 • Communication - 3 • Input - 1 • Output – 4Most hardware faults have been related to lightning or improper installation procedures
  37. 37. PLC System Presentation.doc 1/2/01 RELIABILITY AND AVAILABILITYAvailabilityPeriod Hours of operation Hours lost (due to PLC related faults)1995 – 2000 40K+ 18System available – 99.9996%

×