试论变频器和PLC在卧式带锯床上的应用

杨村煤矿机修厂J4025-1B型卧式带锯床电气控制系统原采用继电控制,运行一段时间后故障率高,工作可靠性差。严重影响了正常的生产工序。为确保该系统安全高效运行,采用了具有当今先进水平的PLC控制变频调速系统进行了改造。改造后,该系统运行稳定可靠,故障率大大降低,提高了工作效率。本文就原继电控制系统存在的缺陷、PLC和变频器的选型、安装运行要求及其维护进行了详实的讨论。     

论PLC自动控制系统可靠性研究

随着科学技术的高速发展,PLC自动控制系统应用越来越广泛,已成为目前微型处理器中的核心部分,也是现代化社会发展的核心内容。因此,PLC自动控制已成为目前相关学者和专家的研究工作重点。经过多年的研究与分析,其可靠性越来越受到人们的关注与重视。本文就对PLC自动控制系统的可靠性要求进行了深入、全面的研究,并提出了提高系统运行可靠性的主要手段和方法。     

基于PLC的自动颗粒包装机热封控制系统

针对包装机的热封质量的要求,设计出PLC控制的包装机热封控制系统,该系统通过PLC实现了设备的PID温度控制和电机的变频调速控制,提高了设备的自动化程度。     

可编程控制器(PLC)控制系统在工业中的应用

本文介绍了PLC定义及特点、和其他系统比较的优缺点以及PLC控制系统的组成和设计,并结合多年现场实际经验,以PLC控制的三泵生活消防双恒压无塔供水系统为例对控制系统的应用进行详细的阐述。     

浅谈对PLC自动控制系统可靠性的认识

近年来,社会各个行业和领域在工作中对PLC自动控制装置的应用逐渐增多。由于PLC系统本身具备着诸多优势而受到人们的高度重视与关注。本文就PLC自动控制系统的可靠性进行全面总结与研究,针对其可靠性运行特点做了简要阐述,并提出了相关的提高方法与建议。     

模糊控制器在空调系统温度控制中的应用研究

控制技术在制冷空调领域的应用有利于制冷空调的优化运行和节能。本文对中央空调系统的模糊控制器的设计做了比较详尽的论述,并结合MATLAB仿真软件对控制系统做了仿真,得到其响应曲线,并与PID控制方法进行比较,从而得出模糊控制器在中央空调系统温度自动控制中具有很高的应用价值[2]。     

基于PLC的粉碎机自动喂料控制系统设计和实现

<正>粉碎机工作过程中,常由于上游喂料速度过快或调节不及时而造成超载甚至堵机,喂料速度过低又会造成粉碎机效能偏低,喂料控制系统在其工作过程中起到了至关重要的作用。本控制系统基于西门子PLC设计了粉碎机负荷调整控制器,成功解决了及时和准确调整喂料量的问题,具有精度高,运行可靠,操作方     

基于PLC的五层并联电梯控制系统设计

本文主要是针对五层并联电梯的控制系统进行设计。在整个设计中,采用PLC技术来控制电梯系统,最后经过系统仿真,可以进行正确的并联电梯系统控制,达到预期的控制效果。     

PLC在新型增塑剂自动生产控制中的应用

本文以西门子可编程控制器为核心,根据新型增塑剂的生产工艺,建立完善的控制系统结构,通过独到的软件设计,解决生产反应过程中的高滞后性温度控制问题,大大提高生产效率和反应的稳定性、可靠性,方便管理,安全操作.     

可编程序控制器在饲料工业自动化方面的应用

可编程序控制器（PLC）是微机技术与传统控制技术相结合的产物,由PLC及智能仪表、强电控制柜构成的集散管理与控制系统,能够实现饲料加工厂各工段的自动控制与单机设备的自动监控及整体工厂集中自动控制。     

Susceptibility to heartwater of calves born to non-immune cows

The resistance to artificial infection with Cowdria ruminantium of calves born to cows fully susceptible to heartwater is no different from that of calves bred in heartwater endemic areas where the tick challenge is negligible to considerable. The sub-inoculation into mice of blood collected 14-26 days after infection proved the presence of the heartwater agent in the blood of 8 out of 10 calves with no other clinical signs than mild to moderate fever. The combined use of a mouse model and the indirect fluorescent antibody test revealed considerable variation in the degrees to which calves become infected and react to artificial infection.     

如何确定奶牛成母牛的投料系数

据有关报道 ,奶牛成母牛的投料系数一般在１５～２５ %之间 ,但是实际情况到底要多少才能既节约成本 ,又满足奶牛成母牛的营养需要 ,也不影响牛奶的质量和产量。为此 ,我们进行了为期一年的实测 ,经过总结和分析认为 :①因为能量所需的投料系数大于其他项（包括ＤＭ、ＤＣＰ、Ｃａ、Ｐ等）的系数 ,所以投料系数以满足能量的需要为主。②投料系数根据不同的月份在７ ３４ %～３３ ５８ %之间。且环境温度越高 ,所需的投料系数越大。大家知道 ,奶牛成母牛的营养需要包括产奶需要、维持需要、生长阶段营养需要、妊娠的营养需要。环境温度变化 ,…     

Failure of lungworm-larvae-infected earthworms to transmit mycoplasmal pneumonia to swine

Two herds of swine, believed to be free from mycoplasmal pneumonia of swine (MPS) based upon negative Mycoplasma hyopneumoniae microtiter complement fixation test (CFT) results, subsequently exhibited clinical signs of MPS.Lungworms (Metastrongylus spp.) were common to both herds. The possibility that lungworms could serve as a reservoir for M. hyopneumoniae was investigated. Lungworm-larvae-infected earthworms, collected from each of the farms, were fed to swine free of lungworms and MPS. This procedure resulted in lungworm infection in the recipient pigs, but failed to produce pneumonic lesions or CFT antibody titers against MPS.     

Failure of young goats to acquire resistance to Haemonchus contortus

Two experiments were carried out to investigate the acquisition by goats of resistance to Haemonchus contortus. In Experiment 1, five Saanen wethers reared worm-free and averaging 5 1/2 months of age at the start of the experiment, were dosed with 200 H. contortus infective larvae three times per week for 10 weeks (approximately 23 infective larvae/kg mean initial liveweight/week) and then given anthelmintic treatment. Each goat and an equal number of worm-free controls were then challenged with 10,000 infective larvae. Post mortem worm counts were carried out 30 days later. In Experiment 2, eight worm-free Saanen wethers, 14 months old at the start of the experiment, were dosed with 825 infective larvae per week for 14 weeks (approximately 23 infective larvae/kg mean initial liveweight/week) except for one week when only 300 larvae were given and one week when no larvae were given. After anthelmintic treatment, each received, together with seven worm-free control animals, a challenge dose of 15,000 infective larvae. Post-mortem worm counts were carried out 28 days later. There were no significant differences in post-mortem worm counts between previously infected and uninfected groups in either experiment. In both experiments, serum pepsinogen values rose significantly as a result of infection but there was no significant (p>0.5) correlation between worm counts and pepsinogen values on the day of slaughter.