Cabinet control systems

Process gas is not the only flow that the controller can monitor for control purposes. Cabinet ventilation flow is also an important parameter and the automatic controller usually monitors this parameter and will shutdown the cabinet system if the air flow through the cabinet is too small. Other signals that should shutdown the entire cabinet include, fire, heat, smoke, or flame detected inside the cabinet, or gas leak detected inside the cabinet. Often cabinet control systems are designed to shutdown if any of these situations occur in the nearby area, or if a separate safety monitoring system sends the cabinet a signal to do so. 

Alarms should be restricted to abnormal situations for which the process operator is responsible. A high alarm on the temperature in one of the control system cabinets should not be issued to the process operator. Correc ting this situation is the responsibility of maintenance, not the process operator. 

The cabinet enclosure has hot water wash hoses with nozzles for any clean-up necessary, and contains both a manual and an automatic fire control system. Lexan plexiglass doors and windows are provided at the front or operating face of the enclosure for observation and access. All doors and enclosures are essentially air tight. 

In the development of the process automation and control system, the required testing of that control system and the factory-assembled components, and the process simulation program must be established with the general functional specifications. In an API facility, many of the control systems perform process functions that require strict validation. The functional description for the automation system should require a complete factory acceptance test (FAT). This test should simulate the entire process and process failures and alarms. The FAT should also check and verify that the control system cabinets and controllers operate as designed. The factory acceptance testing of the process automation system prior to shipment and installation in the field is a critical step in the validation and start-up of the facility. 

The ex-vessel neutron detection equipment consists of fission chamber neutron detectors mounted in six equally spaced vertical wells located just outside the reactor vessel as illustrated in Figure 4.3-4. The signals from these detectors are supplied to the nuclear instrumentation cabinet and Safety Protection Subsystem equipment located primarily in the reactor building. These data are used by the automatic control systems to operate the control rod drives or the reserve shutdown equipment, thereby changing the neutron flux levels within the reactor core. 

Protections include engineering controls, such as biological safety cabinets, controlled access and airlocks, ventilation systems, showers, decontamination facilities, and potentially separate buildings. There are also administrative controls, such as protection from needle and other punctures and cuts ( sharps ), written manuals for operations, and other procedures. There are recommendations for personal protective equipment (PPE) for each BSL. 

The reactor protection system and engineered safety features component control system use fiber-optic technology for isolation between protection system channels and equipment, cabinets and operator interface devices in the main control room. If an isolation error occurs, an appropriate error message is generated and diagnostic tests are then applied to isolate the cause of the error. This would include errors caused by the leakage through a fiber-optic isolator. 

There are a number of automatic monitors available that combine a number of the functions mentioned above into a single unit. These are sometimes connected to the panel s emergency shutoff valve or plant alarm systems, and will usually allow the operator to shut off the cabinet/panel by depressing an emergency shutoff button. For more extensive system control, the automatic gas cabinet controller, explained in the next section, should be used. 

U suaUy, the assembly of the electrotechnical equipment can be carried out absolutely independently from the plant erection, since the control cabinets are accommodated in separate rooms. The same applies to the control system. 

Already today valve-regulated lead-acid batteries are in widespread use in many applications, and this trend will increase in the future since the reduction of maintenance is a signihcant advantage. This battery system requires high quality of all parameters that influence the performance and other characteristics. Valve-regulated lead-acid batteries that are installed in cabinets require sufficient air circulation to achieve equal temperature for all cells or monoblocs. Monitoring or control systems may be used. 

The control unit and control cabinet allow the machine operator to control and monitor the process. Control systems will be discussed in Chapter 5. 

The changes described above also allowed much easier access to the high voltage cable for routine (6-month) owner directed, service operations, and provided better upper and lower x-ray cabinet and control cabinet ventilation. With the exception of the x-ray tubes, all the individual manufactured components, on all four systems are identical. There are very subtle differences in the warm-up/start-up sequence on the x-ray controllers on the newer systems due to model/year and x-ray tube differences. The last three systems were supplied with environmental type key-boards for the image processors and base-mounted , rather than conduit-mounted exterior warning indicators. The first system was subsequently upgraded to include the better keyboard and the external warning appliances/features. 

Automatically Controlled Modular System This method employs one large manually controlled transformer-rectifier used in conjunction with a number of modular cabinets located adjacent to each item of plant requiring protection. The main transformer-rectifier feeds d.c. to each of the module units and the modular unit provides the exact amount of current required by the item of plant in question. 

The equipment used in this application included two Waters M-45 pumps, a Waters 481 UV detector with microbore cell, an air-actuated Rheodyne 7413 injection valve with a 1-pl injection loop, an air-actuated Valeo four-port sampling valve (A2CI4UW2) with no groove in the injection entry ports, an air-actuated Valeo three-port switching valve (AC3W), and a Digital Equipment LSI-11/23 microcomputer. The LC system was located in a purged cabinet suitable for use in Class I, division 2 areas. The cabinet was in a heated room about 40 feet from the reactor column. The two Valeo valves were mounted next to the reactor column, while the microcomputer was located in the control room. 

A main control and annunciator panel should be installed when the fire alarm system requires more than a single alarm zone. The panel should be installed in the control room or other continuously staffed location. Separate detection zones should be provided for each distinct fire area and identified by a permanent label. A detailed map of the area should also be provided at the annunciator that identifies which zone relates to which annunciator lamp. Systems with more than ten separate zones should be provided with an electric or electroniczone "mimic" panel showingthe location of all alarms on the graphic display of the platform. Basic arrangements of equipment and system design should be in accordance with NFPA 72. A locked main fire panel and control cabinet should be provided. 

For mashed potato texture, profile analysis (TPA) and cone penetration tests are performed with a TA HDi Texture Analyser (Stable Micro Systems Ltd, Godaiming, UK). During the tests, the mashed potatoes are kept at 55° C by means of a temperature-controlled Peltier cabinet (XT/PC) coupled to a separate heat exchanger and PID control unit. For the cone penetration tests, a spreadability rig is used, consisting of a 45° conical perspex probe (P/45°C) that penetrates a conical sample holder containing 7 0.1 g of mashed potatoes (Alvarez et al., 2005 Canet et al., 2005b Fernandez et al, 2006). 

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