API552-1994中文

王天泽

利用时间和@gubai0348 一起翻译了API552-1994第3节，内容如下：3 General概述

3.1  ADVANTAGES OF TRANSMllTED SIGNALS传输信号的优点

Transmission systems permit operationof one or more large or small process units from a remote control center.

传输系统允许从远程控制中心操作一个或多个或大或小的过程单元。

3.2 DESIGN CONSIDERATIONS FOR TRANSMISSION SYSTEMS传输系统设计注意事项

The following major factors should beconsidered in the design of transmission systems: 在传输系统设计中应考虑以下主要因素：

a. The relationship of time constantsamong process, transmission, and control lines, since this relationship may influencea control loop's actual performance. This problem is primarily associated withpneumatic transmission.

过程、传输和控制线之间的时间常数之间的关系，因为这种关系可能会影响控制回路的实际性能。这个问题主要与气动传输有关。

b. The reliability of air and electricpower supplies.

气源和电源的可靠性。

c. The routing and installation of tubing,wiring, and piping to maintain circuit integrity; to reduce the possibility of damagefrom fire, overheating from hot process lines or equipment, and mechanicalabuse; and to ensure immunity from electrical and radio-frequency interference.

管路、电缆、穿线管的排布和安装，以保持电路的完整性；减少因工艺管线、设备热源或者机械过载引起的过热、起火；做好电气、射频干扰的屏蔽。

d. The resistance of material andconstruction to corrosion caused by chemicals in the atmosphere or splatterfrom new construction or maintenance.

材料和施工应考虑化学气氛或飞溅中的抗腐蚀问题。

e. Provisions for manual control, testing,and ready access to instruments for maintenance.

手动控制、测试和随时进入维修仪器的规定。

f. Safety requirements and the effect offederal, state, and local regulations and of national and local codes.

安全要求和联邦、州和地方法规以及国家和地方法规的影响

3.3ELECTRONIC电子

The preferred signal transmission todayis electronic.Electronic methods and needs are discussed in depth in this document,starting with Section 4.

目前信号传输首选电子传输。本文件从第4节开始深入讨论电子传输的方法和需求。

3.4 PNEUMATIC气动

Pneumatic signals are used todayprimarily in older plants and where there is a special advantage to pneumatics.The advantages, needs, and recommended methodasr e discussed in this document,starting with Section 21.

气动信号现在主要用于老厂或者气动有特殊优势的地方。优点、需求和推荐的方法，在本文件中从第21节开始。

3.5FIBER OPTICS光纤

Fiber optics isthe phrase applied to the usoef transparent glass or plastic fibers to canylight signals between devices. Fiber optics is a maturing technology and willfind more use in the future. At present, use is usuallylimited to dedicated cables between portions of control systems, and for somespecial applications. Cables, connectors, and matching electronics are available.The user is cautioned to verify that the cable selected is appropriate for theapplication in strength and mechanical makeup, and that the electronics areappropriateI.f the signal power is limited to Light Emitting Diode (LED), sources,rather thana Laser source, there is little conceorfn i gnition of hazardousvapors. If the cable has no metal components which could carry electrical currents,then fiber optics provides complete electricalg, alvanic, isolationbetween the connected devices, thus eliminating concernofs ground currents.

光纤是一种由透明玻璃或塑料纤维制成的材料，用于在设备之间传送光信号。光纤是一种成熟的技术，在未来会有更多的用途。目前，仅用做控制系统部件间的专用电缆或一些特殊场合。在电缆、连接器和配套电子产品等方面均可使用。需提醒用户确认电缆的结构和强度符合要求，且满足电气特性。如果信号源仅限于发光二极管（LED）光源，而不是激光源，几乎可以不涉及危险气体的燃爆。如果电缆不能有传输电流的金属部件，那么光纤就可以在连接的设备之间提供完全的电气隔离，从而消除接地电流的隐患。

3.6DIGITAL FIELD BUS数字现场总线

Several proprietary digitalcommunications schemes are available today for field instruments, and standardsare under development to permit convenient interconnection. Digital communicationsbetween microcomputer-based devices can utilize the intelligence of the devicesto improve accuracy, to improve utility, to reduce Check-out costs, and tofacilutate further advances in control and control systems. These techniques alsoallow multiple devices to share one wire pair to reduce wiring costs. Where metallicwiring is used, the usual concerns of grounding, electrical surge, andelectrical safety

all apply.

目前有几种专有的数字通信协议可供现场仪器使用，正在开发标准，以方便互连。微机设备之间的数字通信可以利用智能设备提高准确度，提高实用性，降低检查成本，并可促进控制系统的发展。这些技术还允许多台设备共用一根电缆，以降低布线成本。在使用金属布线时，通常要考虑接地、电涌和电气安全等问题。

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