1、Technology and Application of Fieldbus Control System -Intelligent Equipment & Measurement And Control System Based on DeviceNetPromoted by the new technological revolution that automation control technology is tending digitization and internet in the field of automation industry, Shanghai Aton Elec
2、tric Co., Ltd. developed Intelligent Equipment & Measurement And Control System Based on DeviceNet as a high and new technology industrialization model project. It was a state hi-tech development project of 2000 and was approved by the State Committee of Technology. Shanghai Aton Electric Co., Ltd.
3、constructed production line of intelligent controller of pump and valve, relying on Shanghai Electric (Group) Corporation; constructed measurement and control system FCS R&D center of intelligent controller of pump and valve and built up mass production R&D basis, cooperating with Shanghai Jiaotong
4、University and Shanghai University; constructed FCS remote diagnosis and service center of intelligent controller of pump and valve; constructed FCS training center of intelligent controller of pump and valve; founded mass production R&D basis along with the Rockwell Laboratory of Shanghai Jiaotong
5、University and CIMS Center.1 Summary(1) Fieldbus control system is a system applied to field of production and microcomputerized measurement control equipment to realize both-way multinode serial communications. It is also called low-level control network for open, digital and multiplespot communica
6、tions.Application: Flow Control System of Manufacturing; Process Control System; Traffic Control & Management; Building Automation.Features: Fieldbus control system is low-level low-bandwidth digital communication and control network in industrial system as well as open system connecting microcomput
7、erized appearance. Intelligent instrument and controller are equal to microcomputer. They make up network with Fieldbus control system as the links to complete digital communication and other tasks.(2) Difference between FCS and DCS,FCS is updated control system after DCS integrated with digital con
8、trol system and distributing control system. It solves the problem that in traditional DCS, devices made by different manufacturers cannot be connected. They cant realize exchange and operation to organize an network system with wider range of information sharing. It conquers the defect that special
9、 closed system for network should be used for communication in DCS to realize various functions of integrated automation. It turns the distributing structure combiningconcentration with deconcentration in DCS into new-type full distributing structure. It releases the control function to the field th
10、oroughly and makes it possible to realize basic control function by means of fieldbus equipment itself. FCS breaks the traditional structure form of control system. The traditional analog control system adopts one-to-one equipment tie-wire and puts up connections respectively according to control lo
11、op. FCS adopts intelligent field equipment to place the control module, all input/output modules that used to be in the control chamber of DCS into field equipment. Since field equipment has ability to communicate, the field measuring and transferring instruments can transfer signals to actuating me
12、chanism such as valve directly. Its control function can be fulfilled directly on the spot independent of the computer or control meter in the control chamber, which realizes thorough decentralized control.FCS adopts digital signals to replace analog signals so that multiple signals (including multi
13、ple operating parameter values, device status and failure information) can be transferred on a pair of cables. Meanwhile, it can give power supply to several devices. No switched block for analog/digital or digital/analog is needed besides fieldbus.(3) Characteristics of FCS Open System; Interoperab
14、ility; replace ability of devices made by different manufacturers. Intelligentize and Autonomy; Field equipment completing basic functions of automatic control. Decentralized System Structure; Field Adaptability; Relatively Strong Interference Killing Feature and Safety Intelligentized local equipme
15、nt can save investment and quantity of hardware Saving installation expenses and cables Saving daily maintenance expenses Enhancing accuracy and reliability of system Enhancing initiativeness of system integration for users(4) Development Background and Trend of Fieldbus Control System,With the rapi
16、d development of computer and computer network, FCS has been rapidly developed as the interlinked communication network between the field intelligentdevices in the field of process automation, building and traffic etc. Because FCS meets the needs that industrial control system is developing in the w
17、ay of decentralization, network and intellectualized, it has become the focus of global industrial automation and been universallyconcerned by the whole world. FCS has caused great revolutions on the aspects of system structure and function system for the current production of automation instrument,
18、 distributing control system and programmable controller. It is predicted that FCS will be the general trends in a very long time in the future fore sure.2 APPLICATION OF RELAYThe product reliability generally refers to the operating reliability. It is defined as: the ability of accomplishing the sp
19、ecified function under prescribed conditions and in prescribed time. It consists of intrinsic reliability and application reliability. The intrinsic reliability is determined by product designing and manufacturing technique, and the application reliability is concerned with the correct application o
20、f users and the services provided by the manufacturer before and after selling. When using relay, the user should pay attention to the following items.2.1 Coil applied voltageIt is best to choose the coil applicative voltage according to the rated voltage in design, or choose the voltage according t
21、o the temperature rising curve. Using any coil voltage that is less than the rated voltage will affect the operation of the relay. The coil operating voltage refers to the voltage that is applied between the coil terminals.The voltage value between the two terminals must be guaranteed, especially wh
22、en using enlargement circuit to energize the coil. Whereas, it will also affect the relay characteristics if the applied voltage exceeds the highest rated voltage. Exorbitant voltage will bring exorbitant coil temperature rising, especially in high temperature ambient. Exorbitant temperature rising
23、will damage the insulating material and affect the working safety of relay. For magnetic latching relay, energizing (or return) pulse width should not less than 3 times of the operating (or return) time, otherwise, the relay would be left on the middle-position state. When using solid-state componen
24、ts to energize the coil, the components dielectric strength must be above 80V, and the leakage of current must be as little as possible to ensure the relay to release.Energizing power source: Under 110% of the rated current, the adjusting ratio of the power source is less than 10% (or the output imp
25、edance is less than 5% of the coilimpedance), the wave voltage of the DC power source is less than 5%. The AC wave is sine wave; the waviness coefficient is between 0.951.25; wave distortion is within10%; the frequency change is within 1Hz or 1% of the specified frequency (choosing the bigger value)
26、. The output power should not less than coil power consumption.2.2 Transient suppressionAt the moment when the coil power is stopped, peak-inverse voltage that is more than 30 times of the coil rated voltage is produced on the coil, which is harmful to the electronic circuit. Generally, the peak-inv
27、erse voltage is suppressed by transientsuppression （cutting-peak） diode or resistance to limit the peak-inverse voltage within 50V. But the diode in parallel connection will delay35 times of the release time. If the request of the release time is high, a suitable resistance in series can be putted w
28、ith and at one end of the diode.The power supply to relays in parallel connection and series connection, When several relays in parallel connection are supplied, the relay that the peak-inverse voltage is higher will release power to the relays that the peak-inverse voltage is lower. The release tim
29、e of the relay will delay. So the relays in parallel connection should be controlled separately to eliminatemutual influence.The relays with different coil resistance and power cant be used in series, otherwise, t he relay that the coil current ishigher in the series circuit cant operate reliably. O
30、nly the relays of the same specification can be used in series, but the peak-inverse voltage will be increased and the peak-inverse voltage should be suppressed. Resistance in series can be used to bear the part voltage that exceeds the rated voltage of the coil according to the ratio of the divided
31、 voltage.2.2.1 Contact loadThe load applied to the contacts should be accordant to the rated load and characteristics of the contacts. A load that is not applied according to the rated value range will cause problem. The relay that is only suitable for DC load cant be used in AC occasions. The relay
32、 that can switch 10A load cant always reliably operate in low level load (less than 10 mA6A) or in dry circuit occasions. The relay that can switch single-phase AC power source isnt always suitable to switch two single-phase AC loads that arent synchronous; the relay that is only specif ied to switch the load of AC 50Hz（or 60Hz）cant be used to switch AC load of 400Hz.2.2.2 Parallel and series connection of contactsThe contacts used in parallel connection cant increase the load current, because the operating times of several sets of contac
