Operator station

Distanee, e.g. spaeing of equipment, operating stations, storage, buildings. 

Figure 8.3 shows the global distribution of existing hydrogen refuelling stations. Black spots represent operational stations, grey spots, planned stations and white ones indicate expired stations. 

The central computer is called the master terminal unit, or MTU. The MTU has two main functions to periodically obtain data from RTUs/PLCs and to control remote devices through the operator station. The operator interfaces with the MTU using software called human machine interface (HMI). The remote computer is called the program logic controller (PLC) or remote terminal unit (RTU). The RTU activates a relay (or switch) that turns mechanical equipment on and off. The RTU also collects data from sensors. Sensors perform measurement, and actuators perform control. 

A control panel receives information from the sensors and sends it to an appropriate location, such as to a central operations station or to a twenty-four-hour monitoring facility. Once the alarm signal is received at the central monitoring location, personnel monitoring for alarms can respond (such as by sending security teams to investigate or by dispatching the fire department). 

Each of the independent controllers is linked to a human-machine interface (HMI) network. Dedicated HMI operator stations are assigned to each area, with an appropriate number of redundant stations providing backup in case of maintenance or breakdown. A development station permits tooling changes between campaigns to be carried out at the same time as systemiza-tion is carried out on the individual areas. A redundant set of historical data collection stations ensures that all of the data are collected and stored for both regulatory... 

Fig. 7.103. Operator station showing video terminals and keyboards (Fisher PROVOX system)...

In an entirely new plant, however, various DCCS components will be housed in local control rooms (LCR) or in outstations. The primary operator stations (OS) and... 

The data highway (which is the main artery of communication) connects the various DCCS components to the host and operator stations. Figure 7.105 demonstrates the distributed architecture of a typical DCCS. 

This consists principally of the host which is used to supervise several process areas and may well have six or more data highways linked to it. Hosts are powerful computers with their own operator stations and other peripherals. They are an integral element of modern control systems and only very small processes may be controlled and monitored effectively without a host. However, if not configured properly, a host computer can be overloaded quite easily and will then fail to operate satisfactorily. One serious loading problem for a host is the fast scanning rate required for DDC loops (usually once per second and up to three times per... 

A number of the basic characteristics of operator stations (OS) are described in Section 7.19.4. Distributed computer control systems normally offer two types of operator station, a stand-alone OS, and a host-dependent OS. Both provide a logical display hierarchy which, if properly configured, improve significantly the... 

CON Concentrator. OS Operator station. CM Control module. PLC Programmable controller. DM Data acquisition module. HC Hiway controller. 

In addition to the above, a number of on-line and off-line diagnostic displays are provided in order to locate system failures promptly and to enable faulty components to be repaired. Most operator stations offer facilities which allow graphic and mimic displays to be built. 

All the displays described above can be implemented on the host s operator station. However, the latter must not be used as the primary operator interface. 

It is important to employ the correct type and quantity of operator stations. For a typical process, with say 2000 I/O, a minimum of three stand-alone operator stations and one host operator station is recommended(S6>. The host operator station is used for those tasks which are beyond the capability of the stand-alone operator station (see Section 7.20.3). 

COP documentation will be continuously available to operators at each operating station where COP instrumentation is located. 

Workstations. Workstations are the most powerful computers in the system, capable of performing functions not normally available in other units. A workstation acts both as an arbitrator unit to route internodal communications and as the database server. An operator interface is supported, and various peripheral devices are coordinated through the workstations. Computationally intensive tasks, such as real-time optimization or model predictive control, are implemented in a workstation. Operators supervise and control processes from these workstations. Operator stations may be connected directly to printers for alarm logging, printing reports, or process graphics. 

Typically, a remote afterloader is a shielded cell or treatment room. Long cables pass through the wall of the room from an operating station outside the room to a patient treatment position inside the room. Radioactive sources are attached to the cables at the patient treatment position. With the patient in the treatment room and the shielded room door closed, the sources are advanced to the treatment position in previously installed applicators by means of the cables and a mechanism in the control system outside the treatment room wall. Our goal was to adapt sources containing up to 200 yg of 252 f to use in these remote afterloaders. 

The primary process operations are conducted sequentially in the same tungsten crucible. These primary operations are conducted in a circular processing assembly with operating stations dedicated for each operation. Decladding is conducted at the first station, oxide reduction is conducted at the second station, FP-3 donor is conducted at the third station, and U-Pu donor is conducted at the fourth station. Each station has the necessary apparatus to conduct the desired operations (introduction of fuel assembly, stirring, and transfer of molten salt and metal phases into and out of the crucible). Figure 4 gives a cross section view of the turntable. 

At each of these operating stations, a furnace (with an open bottom) is suspended from the cover of the processing assembly. 

At each of the operating stations a tungsten crucible is located on the turntable. After each operation is completed, the turntable is rotated for the next operation. Prior to rotation, the turntable (and crucibles) must be lowered so that the stirrers and transfer tubes will not obstruct the rotation of the crucibles. After rotation, the crucibles are raised back to the operating level at the new operating position. The mechanisms and seals for raising, lowering, and rotating the turntable are located below the heated zone of the furnace. 

Consider element sharing. That is, operators/station need not be 1.0. One possibility is more than 1 operator/station. Two operators/station yields 2.0 operators/station. Three operators/two stations yields 1.5 operators/station. This permits a cycle time that is less than an element time. For example, with 2 operators/station, each would do every other unit. 

Get fewer than 1 operator/station by having operators walk between stations or having work done off-line (i.e., using buffers). Also, operators from adjacent stations can share elements. For example, station D does half of element 16 and 17 and station E does half of element 16 and 17. 

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