CCC和WOODWARD有ITCC系统吗? 伍德瓦德： micronet tmr weaknesses 3-2-0 cpu failure mode only – the micronet tmr will trip if two cpu’s fail. 3-2-1 failure operation is not possible. multiple i/o cables for term panels. – the i/o cables from the i/o modules to the term panels must be triplicated. triplication is done outside of the chassis. no keys for i/o cables – the i/o cables that connect field termination modules to the i/o modules do not have any type of “key” mechanism to prevent connecting the wrong i/o module to the term module no keys for i/o slots – no type of “key” mechanism is provided to prevent inserting the wrong type of i/o module into a particular chassis slot. input triplication handled at the application program level – the operating system does not handle the input triplication. this must be done in the application system. a failure of the kernel, the i/o module or the channel must be recognized; the application program must recognize the fault and adjust the program voting accordingly. extensive truth tables must be built for every input to manage the signal validity output triplication handled at the application program level – the operating system does not handle the output triplication. a failure of the kernel, the i/o or the channel must be recognized. if, for example, a channel fault occurs on kernel a and a module fault occurs on c, the application program must redistribute the output to kernel b. no full triplication of high current outputs to servo coils – the outputs of the high current analog output module are not triplicated to both coils of a dual coil servo valve. two kernels connect to one coil and the second coil is driven by the third kernel. if one of the coils in the servo valve fails, the turbine must be shut down to fix the coil. for this reason, the failed coil will likely be left un-repaired for some period. if the coil that fails is the one driven by the two kernels, a failure of the third kernel will result in a trip. discrete outputs voted at the field termination module – voting of the discrete output must be done using a block of six relays on the termination module. a relay failure requires repair of the termination panel and shutdown of the turbine. the configuration of the relays (nc or no) must be done by changing the relays. the application program must perform the latent fault detection testing. single power supply for each kernel – each kernel has a single power supply for providing the power to all i/o modules in the kernel chassis. no voltage regulation is done on the i/o module. a failure of the power supply in a kernel will result in a loss of all the i/o modules in that kernel. speed input restricted to limited range – in the application program, the speed range must be selected with limits the maximum speed that the speed module will detect. the software will only detect a minimum speed of one-fiftieth of the speed range. a filter must be applied (eight milli-seconds or sixteen milli-seconds) due to the noisy nature of their speed detection circuit. limited low speed sensing – with passive speed probes, the lowest speed that can be detected by the speed module is 100 hz. with a 30 tooth gear, this translates to 200 rpm. analog input modules cannot accept a voltage input – in the tmr configuration, the micronet will only accept current inputs. no hot spare slots – to repair a failed i/o module, the module must be removed, causing all the inputs on that module to be lost during the repair procedure. no hot spare slot exists for installing a spare before removing the faulty module. i/o cable must be removed to repair a module – each i/o module has it’s own i/o cable to connect it to the ftm. if the module must be replaced the i/o cable must be disconnected from the module. minimal i/o capability – the micronet tmr is limited to only six i/o slots. in order to accommodate all the i/o required for this application, woodward must use their remote i/o. the remote i/o is simplex and handled by a very slow echelon network. no expansion chassis are available with the micronet complicated cpu replacement – the application program is located on an eeprom on the cpu. to change a cpu, the eeprom must be removed from the faulty cpu and installed on the new cpu. no tuv certification – no woodward products are tested by tuv for safety integrity. no unique connectivity to the dcs – the only communication links available for connecting to the dcs is modbus. poor adaptation to gas molecular weight changes in surge control algorithms – when woodward developed their surge control algorithms, the essentially copied the old ccc algorithms. essentially they attempt to measure the compressor head. in order for this technique to be effective, the system must know the molecular weight of the gas. there is not a real-time technique to measure molecular weight. ccc 美国公司，主要产品是ccc venguard s5双重化系统。 ccc venguard s5 美国 双重化 双重冗余结构。在国内单机组防喘振控制有一些应用。稳定性及可靠性一般查看更多
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