silo 3 - U.S. Department of Energy

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Process Control Plan for the Silo 3 Project
Document No. 40430-PL-0003, Rev. 1
Jacobs Proiect Number 35H19605
September 5,2003
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sequencing, alarm monitoring, and interlocking is performed in the PLCs. Use of relay
logic, individual timers, and interlocks external to the PLCs is avoided. An exception to
this is the emergency stop circuits, which are hard-wired and also have PLC inputs to reset
process PLC control functions as required.
Operator push buttons, hand switches, conveyor controls, motion detectors, solenoid
valves, etc., are configured as inputs and outputs WO) to the PLC control system. Discreet
input circuits are 120 VAC; discrete output circuits are either contact-closure or 24 VDC;
and analog l/O circuits are 4-20 mA. Detailed I/O information is provided .in Attachment
A.
Packaging area control stations are suitably configured for manipulation by operators who
are in a standing position alongside the associated equipment. A primary Allen-Bradley
touch screen control station is provided at each of the two Package Loading Stands. Other
small local control stations are provided as required for peripheral devices such as loading
area conveyors and building airlock doors. An additional Allen-Bradley touch screen is
installed at a convenient location for Packaging Area operators to monitor and control
related overall facility functions, (such as the PRS or MRS operations) and facility utility
functions.
A local area network is installed to link all the PLC processors, the HMI PCs, and the
Packaging Area touch screen displays. The communication format is Ethernet 1 OBase-T in
accord with the communication facilities built into the .Allen-Bradley SLC5/05 processors
and other field display stations. A configurable Ethernet switcher is provided with a
0 sufficient number of ports for future expansion. .-
All of the Control Room PCs, the main process PLC and packaging line PLCs, and the
touch screen displays are powered from the Uninterruptible Power Source (UPS). This
eliminates control system disruptions and processors reboot delays. Actual process
equipment, including all conveyors, fans, etc., do not have backup power. The PLCs are
programmed to turn all output circuits off and to reset all process functions on utility
power loss.
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