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Managed by UT-Battellefor the Department of Energy
SCL Vacuum Control System Upgrade
Derrick Williams
2 Managed by UT-Battellefor the Department of Energy Presentation_name
Design Scope of the SCL Vacuum Upgrade
Upgrade the Super Conducting Linac (SCL) Vacuum System to a PLC Control System.
1. INCREASE RELIABLITY: Reduce the number of control components!
Old configuration: Custom built chassis, Two Beckhoff I/O stations, External “AND/OR” Gate Relays and Hytec serial control per vacuum rack.
New configuration: One PLC and one Digi PortServer for serial control per vacuum rack.
2. REDUCE DOWN TIME: The Original custom boards are not hot swappable; chassis has to be powered off and that means RF on 4 cryo modules will be off during this time. PLC allows by-passes installed via software and logic changes can be made on the fly. New chassis has easy access to troubleshoot I/O. The new serial interface will not require the IOC to be rebooted on regular intervals.
3. AVAILABLITY OF SPARES: All custom built hardware will be replaced with standard PLC and off-the-shelf components. Serial communication hardware: Hytec (UK built hardware) replaced with Digi PortServers.
4. CONTROL SYSTEM FLEXIBILITY: PLC code is easily changed and hardware can be expanded for future modifications.
3 Managed by UT-Battellefor the Department of Energy Presentation_name
Design Effort
1. Hardware: PLC system with PLC chassis to interface with existing field cable infrastructure; Digi solution for serial control; fast valve controller to use existing field cables and interface with PLC system
2. Software: IOC and PLC code development, Digi serial control, and operator screens
3. Documentation: Develop test plans for new PLC vacuum control system for each cryomodule & warm section. Create design drawings for PLC interface chassis and field wiring
4 Managed by UT-Battellefor the Department of Energy Presentation_name
Challenges to upgrading any control system in a short maintenance window
1. Maintain the design integrity for protecting the equipment. New design must meet or exceed the original design
criteria Detail test procedures must be written before installation
and completed before returning system to operations.
2. Be as transparent to operations as possible The upgrade needs to fit in the outage window as not to
impact the facility’s run schedule.
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PLC Response Time for Interlocks
The time for the MKS controller to respond to a vacuum increase above the relay setpoint and output a signal to the PLC is ~13 msec. By using a periodic task with a scan rate of 2 msec and by limiting the amount of logic in that task, the Allen-Bradley 1756-L62 processor response time is less than 2 msec. Also, the scan rate for the digital input module has to be set at a fast scan rate to achieve the desired PLC response time. The overall response time for a vacuum pressure to increase above the interlock limit and for the PLC to output a 24VDC signal to the LLRF system to turn off RF power to a cavity is ~15 msec
At SNS it is required that RF power to a cavity be turned off within 16 msec of a vacuum excursion (typically due to an arc). The MKS gauge controller provides an analog pressure reading and a relay digital output that can be used to sense pressure exceeding a threshold. The PLC uses both signals to interlock the RF power to a cavity. However the analog signal is processed much slower than the relay digital input.
6 Managed by UT-Battellefor the Department of Energy Presentation_name
The SCL Vacuum System was broken down into 8 sections
Picture is 1 of 8 vacuum racks for SCL Vacuum System. SNS uses the MKS 937A gauge controller and Varian dual ion pump controller.
Original vacuum rack with J- lab equipment.
7 Managed by UT-Battellefor the Department of Energy Presentation_name
PLC 3….8
Digi PortServer
SCL Vacuum Block Diagram
PLC InterfaceEnd Chassis
ION PumpController
GaugeController
SCL_Vac:PLC2
ION PumpController
GaugeController
SCL_Vac:PLC1
CM-1 CM-2 CM-3 CM-4 CM-5 CM-6 CM-7 CM-8 ….
Zone 1 Zone 2 Zone 3 - 8
Field Devices
PLC InterfaceMiddle Chassis
Field Devices
SCL_Vac:IOC
Ethernet
Digi PortServer
LEDP
Fast ValveController
Repeats for Zones 3 - 8
New Components
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EPICS Screen Shot for LEDP & CM1
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Upgrade ChangesBefore and After Front View Installation Photos
Beckhoff I/O
Beckhoff I/O
Custom Hardware
Custom Power Supply
Before After
A/B PLC
PLC Interface Chassis
Auto transfer switch for AC
power.
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Upgrade Changes
Before and After Rear View Installation Photos
Custom Hardware
Beckhoff I/O
“AND” Gates for LLRF Interlocks
Custom Power Supply
Before
Digi PortServer
PLC Interface Chassis
24V Power Supply
PLC Output for LLRF Interlocks
After
11 Managed by UT-Battellefor the Department of Energy Presentation_name
New Hardware is COTS
Allen-Bradley PLC
PLC interface chassis; all parts are COTS
VAT fast valve controller
Digi Portserver 16 configurable ports for RS-232
and RS-485
All the new hardware is readily available and commercial off-the-shelf (COTS)
All materials were staged up for each vacuum rack before the upgrade started!
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Important to Plan and Test !1.It’s very important to include lab test time in your cost estimates as well as the schedule.
2.Don’t try to install more than possible in an outage window. The first system installation will have some learning curves.
3.We only upgraded 1 system to validate the design and installation plan on the first outage. Then we were able to install 2 and 3 systems during an outage.
4.We were able to install 1 vacuum rack upgrade and have the system controlling through EPICS in 1 day. The interlock procedures would take several days to complete.
Date Zone Cryomodules Installation Status
Feb-08 2 5-8 Complete
Jul-08 3 9-11 Complete
Jul-08 4 12-15 Complete
Oct-08 1 1-4 Lab Tested
Jan-09 1 1-4 next to be installed
Jan-09 5 16-19 next to be installed
Aug-09 6 20-23
Aug-09 7 Dummy 24-27
Aug-09 8 Dummy 28-32, LEDP
13 Managed by UT-Battellefor the Department of Energy Presentation_name
Keys for a Successful Upgrade· Plan, plan, plan, test, test, test!
1. Cost and schedule not only the installation portions, put include lab testing, procedure writing, etc. It’s often overlooked and it adds up more than you think!
2. We were able to mockup a vacuum rack in the lab to test every I/O point, PLC logic, and EPICS screen. This is also a good opportunity to walk thru the test procedure.
· Transparent to Operations1. Break large systems down into manageable sections to fit in
the outage window. The upgrade should not impact the operations of the facility if possible.
· Documentation1. Test procedure are critical and every combination of the
systems interlocks and logic needs to be included. If it’s not written down you will overlook it!
2. As-built drawings and finalized procedure versions soon after installation is complete.
