Application of PLC to dynamic control system for liquid He cryogenic pumping facility on JT-60U NBI system

Improvement of Strength and Impact Toughness for Cold-Worked Austenitic Stainless Steels Using a Surface-Cracking Technique

For cryogenic applications, materials must be cautiously selected because of a drastic degradation in the mechanical properties of materials when they are exposed to very low temperatures. We have developed a new technique using a cold-working and surface-cracking process to overcome such degradation of mechanical properties at low temperatures. This technique intentionally induced surface-cracks in cold-worked austenitic stainless steels and resulted in a significant increase in both strength and fracture at low temperatures. According to the microstructure observations, dissipation of the crack propagation energy with surface-cracks enhanced the impact toughness, showing a ductile fracture mode in even the cryogenic temperature region. In particular, we obtained the high strength and toughness materials by a surface-cracking technique at 5% cold-worked specimen with surface-cracks.

Development of an automatic subsea blowout preventer stack control system using PLC based SCADA

An extremely reliable remote control system for subsea blowout preventer stack is developed based on the off-the-shelf triple modular redundancy system. To meet a high reliability requirement, various redundancy techniques such as controller redundancy, bus redundancy and network redundancy are used to design the system hardware architecture. The control logic, human-machine interface graphical design and redundant databases are developed by using the off-the-shelf software. A series of experiments were performed in laboratory to test the subsea blowout preventer stack control system. The results showed that the tested subsea blowout preventer functions could be executed successfully. For the faults of programmable logic controllers, discrete input groups and analog input groups, the control system could give correct alarms in the human-machine interface.

A water pumping control system with a programmable logic controller (PLC) and industrial wireless modules for industrial plants--an experimental setup

This paper describes a water pumping control system that is designed for production plants and implemented in an experimental setup in a laboratory. These plants contain harsh environments in which chemicals, vibrations or moving parts exist that could potentially damage the cabling or wires that are part of the control system. Furthermore, the data has to be transferred over paths that are accessible to the public. The control systems that it uses are a programmable logic controller (PLC) and industrial wireless local area network (IWLAN) technologies. It is implemented by a PLC, an communication processor (CP), two IWLAN modules, and a distributed input/output (I/O) module, as well as the water pump and sensors. Our system communication is based on an Industrial Ethernet and uses the standard Transport Control Protocol/Internet Protocol for parameterisation, configuration and diagnostics. The main function of the PLC is to send a digital signal to the water pump to turn it on or off, based on the tank level, using a pressure transmitter and inputs from limit switches that indicate the level of the water in the tank. This paper aims to provide a convenient solution in process plants where cabling is not possible. It also has lower installation and maintenance cost, provides reliable operation, and robust and flexible construction, suitable for industrial applications.