Professional English

for Built Environment and Service Engineering

Lecturers: Zhou Jin 周晋 Tel(O): 0731-8821312-202 Mobile: 13723870512 Email: zhoujin_y@263.net

Unit Fourteen

Control and Building Automation System

Fi r e Aut omat i onSyst em

Communi cat i onAut omat i on Syst em

Secur i t y Aut omat i onSyst em

Bui l di ng Aut omat i onSyst em

Syst em I nt egr at edCent er

Of f i ce Aut omat i onSyst em

What is an intelligent building?

Schematic Diagram of an Intelligent Building System

Up to now, there has not been a universally accepted definition for an Intelligent Building.

Most existing definitions of IB around the world centre on the need for a building to be suitable for the occupants to work and live in safely, comfortably, effectively and efficiently.

“Intelligent building is something that make stupid people feel not as stupid as they are”.

Intelligent Building can bring us

Reduced Resource Consumption

Both home and building technology offer tremendous potential savings through intelligent controls.

Optimized Convenience and More Comfort

Apart from minimizing consumption costs, private home owners will be interested in higher levels of convenience, safety and security.

Smart Home is an integration of various systems at home such as security, home automation, lighting control, CCTV and entertainment system which is coordinated by a smart home controller and controlled by users using various centralized command interfaces such as a touch screens, keypads, universal remote controllers, internet browser, telephone, and even your LCD TV screen.

Smart Home SystemsCCTV: Closed Circuit Television

CCTV: China Central Television

On/off Control

The control device can be positioned only to a maximum or minimum state (e.g., on or off). Because On/off control is simple and inexpensive, it is used extensively for both industrial and commercial control. A typical home thermostat that starts and stops a furnace is an example of On/off action.

Floating Control

Dead (neutral) zone

盲区 停滞区

In floating control, the controller can perform only two operations— moving the controlled device toward either its open or closed position, usually at a constant rate. Generally, a neutral zone between the two positions allows the controlled device to stop at any position when the controlled variable is within the differential of the controller. When the controlled variable falls outside the differential of the controller, the controller moves the controlled device in the proper direction.

open

shut

Time

Upper limit

Lower limit

neutral zone

Temperature

Valve

set point

controlled variable

proportional band

output

offset

Proportional control requires a continuously variable output of the controlled device. The control system produces an output which is proportional to the error signal, i.e. the difference between the value of the controlled variable and the set point.

)()( teKtu Proportional control

signalresponse

)( d

)( dteK

t

tu

Integral control

t

tteKtu0

d)()(

t

teKtu

d

)( d)( Derivative control

signalresponse

Proportional plus Integral (PI) Control

Proportional-Integral-Derivative (PID) Control

Proportional Action.

Closed loop controlFeedback

A closed loop or feedback control measures actual changes in the controlled variable and actuates the controlled device to bring about a change. The corrective action continues until the variable is brought to a desired value within the design limitations of the controller. This arrangement of having the controller sense the value of the controlled variable is known as feedback.

Example of Feedback Control

Room Air Temperature Control

Open loop control

An open loop control does not have a direct link between the value of the controlled variable and the controller. An open loop control anticipates the effect of an external variable on the system and adjusts the set point to avoid excessive offset.

An example is an outdoor thermostat arranged to control heat to a building in proportion to the calculated load caused by changes in outdoor temperature. In essence, the designer presumes a fixed relationship between outside air temperature and the heat requirement of the building and specifies control action based on the outdoor air temperature. The actual space temperature has no effect on this controller. Because there is no feedback on the controlled variable (space temperature), the control is an open loop.

Single-Seated Valves Double-Seated Valves

单座阀 双座阀

Three-Way Mixing Valves Three-Way Diverting Valves

三路混合阀 三路换向阀

Butterfly Valve

SensorsTemperature Sensors Humidity Sensors

Pressure Transmitters and Transducers

Flow Rate Sensors Indoor Air Quality Sensors

Lighting Level Sensors

ControllersPneumatic Receiver-Controllers

Electric/Electronic Controllers

Digital Controllers

Thermostats

1. Control Modes On/Off control Proportional control Floating control Integral control Derivative control Variation and Combination of basic modes

2. Open and closed loop control

open loop control closed loop control

3. Building Automation Systems

3.1 General 3.2 Basic Considerations 3.3 Computer Based Systems

Frequently used words and phrases:

control mode 控制模式 On/Off Control 开 /关控制Proportional control 比例控制 Floating control 浮动控制Integral control 积分控制 Derivative control 微分控制Proportional plus Integral (P+I) Control 比例加积分控制Proportional plus Derivative (P ＋ D) Control 比例加微分控制Proportional plus Integral plus Derivative (P+I+D) Control 比例加积分加微分控制final control element (FCE) 终端控制元件Open loop control 开环控制 Closed loop control 闭环控制signal 信号 heater battery 加热器组air curtain 空气幕 sensor 传感器electro-mechanical system 电动机械系统pneumatic system 气动系统 pressure switch 压力开关humidistat 湿度控制器 time switch 定时开关building automation system (BAS) 建筑自动化系统energy management system (EMS) 能源管理系统direct digital control (DDC) 直接数字控制

1. A controller can be made to operate a final control element (FCE), e.g. a valve, damper, or luminaire in a number of different ways in response to a signal.

2. The control mode does not define the means by which control is effected, which may be through mechanical, electro-mechanical, electronic or pneumatic systems.

3. The control sensor usually takes the form of an on/off thermostat, pressure switch, humidistat, time switch, etc. and operates such that below the set point the contacts open.

controller: 控制器 final control element (FCE): 终端控制元件damper: 闸板 luminaire: 照明 signal: 信号

control mode: 控制模式 electro-mechanical: 机电的pneumatic: 气动的

on/off: 开或关 pressure switch: 压力开关humidistat: 湿度调节器 恒湿器

4. Proportional control action refers to a control element having an output signal proportional to its input signal.

5. If the scale range of a temperature controller is from 0oC to 100oC and the proportional band setting is such that the controlled variable must change from through 40oC to 80oC to make the valve move from full open to shut, then the proportional band is (80-40)/100=40%.

6. This mode of operation depends on the use of a dead (neutral) zone in the controlled variable. In this zone the correcting element is not power controlled and remains in its last pulsed position until the controlled variable moves outside the dead zone.

proportional control: 比例控制

dead (neutral) zone: 停滞区 中性区 correcting element: 修正元件pulsed: 搏动的 跳动的

proportional band: 比例带 full open: 完全打开

7. A correcting element may be arranged to remain stationary when the controlled medium is at the desired value and move in a corrective manner at an increasing speed proportional to the deviation from the desired value.

8. This action is used to eliminate overshoot during a fast load change. Derivative control is mainly applied in special process systems.

9. While floating and proportional control actions may be used on their own, derivative control must always be used in combination with proportional or floating action.

stationary: 固定的 不动的 corrective manner: 修正的方式deviation: 背离

overshoot: 超出 超过 过分 load change: 负荷变化derivative control: 微分控制

How to translate????

10. Control systems are applied to control loops, each loop normally comprising one section of an overall plant, e.g. reheater, smoke alarm.

11. When the condition of the controlled variable changes in closed loop control the sensor detects the change and initiates correcting action to final control element.

12. The effect of this is reflected in the controlled variable and reassessed by sensor which continuously provides feedback to the controller.

control loops: 控制环路 comprising: 构成reheater: 再热器 smoke alarm: 烟雾报警器

closed loop control: 闭环控制 detect: 探测 initiate: 触发 开始

reassess: 再评估 feedback: 反馈

13. The simplest form of such a loop would be the detection of smoke where a local/or remote alarm is initiated by a smoke detector without any feedback to the smoke sensor.

14. In this case the output from heater battery serving the air curtain would be modulated in accordance with the outside temperature so that, for example, at 0oC externally there would be full output and at 15oC, no output.

15. Most thermostatic control manufacturers now market buildings automation systems to monitor and control other building services such as energy, security and fire protection systems.

alarm: 报警器 smoke sensor: 烟雾传感器

heater battery: 加热器组 air curtain: 空气幕 modulate: 调整

thermostatic: 温度调节装置的 market: 使…进入市场security: 安全 fire protection systems: 防火系统

16. It is always advisable to question the level and validity of the software offered to perform the tasks required in the context of building services automation.

17. There is often a deep gulf between software capability and the necessary knowledge of building usage patterns and building services operation to produce adequate programs.

18. One other area which requires emphasis is the possible susceptibility of all processor based systems to electrical interference, however caused.

advisable: 可取的 明智的 question: 提出问题 质询validity: 有效性 context: 上下文 领域

emphasis: 强调 susceptibility: 易感性 interference: 干扰 干涉

gulf: 海峡 深渊 差距 隔阂 the Persian Gulf: ???usage pattern: 使用模式

19. The principles apply whether the system has one unit with 10-20 points or multiple processors and outstations serving 10,000 points.

20. It is essential that the specification for any BAS is precisely detailed in terms of all performance, requirements, functional sequences and clearly defined interface conditions for every facility required.

21. A detailed specification of this nature will be more conducive to a satisfactory conclusion than one which concentrates on detailing the precise technology which is to be used for each element of the BAS.

point: 控制点 outstation: 设在边远地区的分站 边远哨所 远程控制中心

specification: 说明 be conducive to: 有益于

BAS: building automation systems 建筑自动化系统detail: 详述 细说 in terms of: 按照 根据 functional sequence: 功能顺序interface condition: 界面条件 facility: 设施

22. The centralization of the logic equipment allows greater flexibility of operations than conventional hard wired systems and also frees maintenance staff from watch keeping duties, enabling more effective use of manpower.

23. It must be considered very early on in the building/plant design concept. If it is added at a later stage it will duplicate a number of other elements which are complete in themselves.

24. The functions of a building automation system could be achieved by hard wired control systems and the economic justification for a sophisticated system includes the fact that the engineering, site wiring and commissioning costs can be a fraction of the hard wired system.

centralization: 集中 logic equipment: 逻辑设备 flexibility: 灵活性hard wired system: 硬件系统 staff: 人员 职员 the teaching staff: ???

economic justification: 经济上的合理性确认 sophisticated: 复杂的site wiring: 现场布线 commissioning: 调试 试运转

later stage: 后期 duplicate: 复制 使…成双倍

25. If process control is to be achieved by direct digital control (DDC) then savings will occur in the elimination (of) local loop controllers and in the avoidance of duplicating sensors for control and monitoring purposes.

26. If it can be shown that a building automation system minimizes the number of failures and reduces the down time, this is a strong factor in the economic argument.

27. Options include fully owned systems and those where third parties own the central building automation equipment and sell a “remote” supervision and control service.

process control ：过程控制 direct digital control (DDC): 直接数字控制elimination: 减少 avoidance: 避免

fully owned: 全权拥有的 third party: 第三方

failures: 故障 失败 down time: 停机时间 argument: 讨论 争论

Direct digital control (DDC) refers to the application of microprocessor technology to building environmental controls.

With DDC it is possible to control heating and cooling functions with software that takes into account a wide range of variables, thereby achieving greater efficiency.

28. In some systems the scan initiation is entirely from central processor which addresses each individual point in turn and then processes the data received.

29. A variation is the use of microprocessors at various location which contain all the intelligence needed for local supervision and control, including DDC, hosted by a central computer having overall control.

30. Many computer based systems allow various control and energy management programs, as detailed later, thus dispending with the need for conventional items of equipment, instrumentation or controls.

address: 分配地址 in turn: 依次 process: 处理

dispend: 浪费

host: 做主机

31. Planned and programmed maintenance schedules can also be produced and monitored by the computer based systems but this normally requires a large memory storage capability and considerable project orientated input data.

schedule: 日程计划 时间计划 orientate: 调整方向