温度发射器比直接有线对应物具有重大进展。消除特殊的布线要求,简化工程和维护,同时实现高级诊断。横正在提供头部安装,面板安装和现场安装设备,以覆盖不同的温度应用。


  • 头安装

    Head Mount发射器提供了一种进行工业温度测量的较便宜的方法。

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  • 面板安装座

    Panel-mount temperature transmitters are designed to be mounted on DIN-rails located in non-harsh environments. With the mounting style, the transmitters can be grouped together for easy access.

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细节

工业温度测量

Temperature is one of the four basic process measurements (others being Pressure, Level, and Flow). Temperature measurements are used in an array of different applications. Inaccuracy of a temperature reading can have an impact on the bottom line.

例如,如果控制器在过程中保持水温在100°F下保持水温,并且温度测量恢复控制器仅比实际温度低1°F,则控制器将增加该过程的能量,以使其达到100°F(尽管真的不需要。)每年这浪费的能源成本会多少?当然,这取决于我们在谈论多少水,但是,如果您每年使用100,000多种水,它的价格是每年8,000美元吗?$ 10,000/年?或者more?小测量不准确的成本(仅1°F)是非常真实的,但经常被忽略。

You can see that it is important to have a good understanding of temperature measurement. The following sections will cover the basics of temperature sensors and why the use of a temperature transmitter is useful.

传感器

多年来,已经开发了许多传感器。所有人都通过传感器的物理特征的某种变化来推断温度。一个很好的例子是汞温度计。随着温度的变化,汞的体积(物理特征)以可预测的方式变化。了解可预测的变化使我们能够以视觉量表构建温度计,我们可以从中读取温度。但是,在工业应用中,我们需要比汞温度计更准确的东西。工业应用中使用的更常见的传感器是电阻温度探测器(RTD)和热电偶(T/C)。

RTD和热电偶之间有什么区别?

RTDs are made from a single material whose electrical resistance changes as temperature changes. Knowing the relationship between resistance and temperature allows us to infer the temperature measured. A common material used for RTDs is Platinum; but, other materials are used as well. Platinum has a stable well-defined resistance change per degree temperature change over a wide temperature envelope. The advantage of RTDs is the stable accurate output over a long period of time. Disadvantages are their initial higher cost and limited measurement envelope when compared to thermocouples (Refer to graph below).

热电偶是由两种不同的电导体that are joined at one end. Changes in temperature at the connection point of the two materials cause a voltage to be generated between them. Knowing the relationship between the generated voltage and temperature allows us to infer the temperature measured. Thermocouples are made out of several different materials combinations. Each combination has a different temperature envelope. Thermocouples are more rugged, less expensive, faster responding and have larger measurement envelopes when compared to RTDs; but, are not as stable and accuracy degrades over time.

热电偶是两者中更常用的。

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Temperature Transmitters

As with all field instruments, the purpose of taking a temperature reading is to get that information back to the controller / monitor in atimelymanner,准确, 和reliably

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RTD和热电偶可以直接连接到接收装置。

那么,为什么要使用温度变送器?

每种类型的传感器都有直接接线的独特挑战。通常,此方法将有一个negative对传感器信号的准确性和可靠性的影响。

RTDS使用扩展线。这些电线增加了RTDS信号的电阻。由于RTD使用电阻来测量温度,因此在达到接收装置时未导致温度的任何电阻都会导致误差。可以使用3线或4线RTD来补偿“额外”电阻。这些额外的电线用于测量接线中的电阻。接收装置可以使用信息来补偿额外的阻力。但是您的运行量为3或4线电缆。该布线最多可使您的两倍是普通的2线电缆的两倍。

热电偶需要特殊的布线将热电偶连接到接收装置。该布线必须由与热电偶本身相同的材料制成。如果使用不同材料的接线,则接收设备将接收损坏的信号。确保在安装过程中可用特殊接线并维护以后维护的电源,从而为热电偶使用增加了层的复杂性。这种特殊接线的成本也是一个考虑因素(尤其是在长时间的接线运行中)。

Temperature Transmitters解决这些问题。可以将发射器放置在传感器附近,以减少所需的特殊接线,从而减少任何潜在误差。发射器将传感器信号转换为可以发射更大距离的信号。该信号可以是简单的4到20mA DC模拟信号,数字信号(HART协议,大脑协议或Findown™FieldBus协议)或无线信号(ISA100)。发射器使用标准扭曲对或无线发射器完全没有电线,向所需的接收设备获得可靠的准确信号。

将信息返回到控制器 /监视器中timelymanner,准确, 和reliably

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Resources

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横川通过提供自己的产品来为过程行业人才的教育做出贡献。vwin官方网站
TAFE昆士兰州学生通过使用Centum VP DC的敬酒颜色来学习过程行业。

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自动锅炉控制的最佳解决方案
传感器and controllers for the efficiency and environmental performance

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考虑到安全性和环境问题,例如燃烧效率以及降低排气中的NOX和CO,对于控制垃圾焚化过程中的O2浓度已经很重要。

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纸浆和造纸行业正在进行连续的技术改进,以获得最佳的性能。改进的植物性能转化为更高质量的改善和较低的成本,并同时具有环境友好的植物运营。

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