】 【Weak current college building automatic control system introduction.

<br> <br> First, an overview <br> <br> Intelligent buildings (InteiligentBuildings) is building technology and computer information technology, information society and economic internationalization needs. Intelligent buildings mainly building automation system (BAS), communication automation system ( .CAS) and office automation system (OAS), the three systems. This chapter mainly on building automation system (BAS) for the exposition. Intelligent buildings tend to be from the start of building automation control system. Intelligent building, there is a wide range .of electrical equipment, such as: environmental comfort needed for air conditioning equipment, lighting equipment and redraw the drainage system of the equipment, the equipment and the powder: more, more control, monitoring, measurement, and up to hundreds to thousands of points; .powder that these devices scattered throughout the various layers and corners. If you have a decentralized, local control, monitoring and measurement. In order to make rational use of devices, saving energy, saving manpower, ensure the safe operation of equipment, naturally presents how .to strengthen the management of the device. <br> <br> In the 1990s, with the computer technology and the rapid development of information technology. For building a variety of device status monitoring and measurement are no longer with the lines, instead of using .scanning measurement. System controlled by the centralized control over the Central and the high processing power of the field controller superseded sets-powder control system, the central machine to provide reports and strain treatment, site controller to the relevant parameters, automatic control equipment to achieve .control objectives. On building equipment computer management system in place of the operator, or for its supplementary measures, is a natural development. Automatic control technology through simple mechanical controller, General instrument control, into a new phase - the computer control. <br> .<br> Second, building automatic control system components <br> <br> In recent years continued the construction of tall buildings in China, it is characterized by high high, multi-layered, size large. Area of up to tens of thousands of .square meters to several hundred thousand square meters. These buildings are one monster, tall stands on the ground, this is its appearance, and the concomitant internal construction equipment is considerable. In order to improve equipment utilization, rational use of energy, strengthening the monitoring .of construction equipment status, and so naturally raises the building automation system. <br> <br> Building automatic control system can automatically control the building mechanical and electrical equipment. Via software, system management of interrelated devices, play equipment overall advantages and potentials, .improve equipment utilization, optimize equipment's operating status and time (but does not affect the equipment ergonomics), thereby extending the service life of equipment, reduce energy consumption, reduce the maintenance personnel's labor intensity and volume of work. Ultimately, reducing the cost of running .the device. <br> <br> (1) the purpose of the management <br> <br> Automatic control, monitoring, measurement is building three elements of the device management, aimed at mastering the operational status of construction equipment, accident, .energy consumption and load variations, etc. Especially in the use of electronic computer can greatly saves manpower and can save energy. General considers that energy savings of 25%. <br> <br> According to the Institute of electrical engineers of Japan said that .technical report: the use of electronic computer management system effect and do not use effect compared to maintenance personnel can be reduced by about 30 per cent. We have talked about energy-saving is necessary, the maximum utilization of energy-saving on. This operation .control of the methods used are: the effective operation of machinery; change of indoor temperature and humidity conditions; control of illumination; the device running time control in minimal; reduce outdoor air amount of people. In a building's internal electrical consumption rate of total energy .consumption by 70% ~ 90%, saving you first from electrical to reduce power consumption. <br> <br> (2) management object <br> <br> Construction equipment management mainly electrical equipment; air conditioning; sanitary facilities. <br .> <br> L) electrical equipment: Management main monitor electrical equipment of machines action state, measuring points and protection devices. The main object is the management of the distribution system, such as circuit breakers, transformers, contactors, fuses, capacitors, and .other State monitoring. Measuring mainly on power system of current, voltage, active power, reactive power and power factor measurements. <br> <br> 2) air-conditioning equipment: management of air conditioning equipment to monitor the refrigerator, air conditioner, .water pump, etc.; the measurement of temperature and humidity, and air conditioning system and heat source of the temperature, flow rate adjustment. <br> <br> 3) sanitary facilities <br> <br> Third, building automatic control system .control function <br> <br> Building, construction equipment and automatic control is centered on the air conditioning control. Automatic control of air conditioning system is of a general process of automatic regulation of thermodynamics. Automatic adjustment of the air conditioning system has the following .benefits: <br> <br> A) productive building can increase the temperature and humidity control precision, improve product quality; on residential and commercial buildings are primarily improve human comfort. <br> <br> B) can be transferred amount changes, .the system changes the energy (heat or cold), so you can reduce energy consumption and save energy. <br> <br> C) can reduce labor intensity. <br> <br> I the automatic adjustment of the air conditioning unit < .br> <br> Control system uses DDC control, installed at the return air duct temperature sensors that detect temperature rushed to DDC controller and set point temperature compared with proportional integral and differential control, output the appropriate voltage signal, control the return pipe on electric .regulating valve of the action, the return air temperature in the range. <br> <br> The air humidity sensor in the detection of moisture to the DDC controllers in comparison with the humidity set point, use the PI control, output the appropriate voltage .signal, control electric steam valve movement, so keep sending rheumatism of the range. <br> <br> Installed at the return air ducts and air supply pipe temperature and humidity sensor detection of temperature / humidity rushed to DDC controller for air andFresh air enthalpy .value calculation, press the back to the wind and the proportion of fresh air enthalpy value, output the appropriate voltage signal, control the return air throttle and the proportion of fresh air throttle opening of the system. <br> <br> 1) system .are all inspection data can be displayed on the display, such as: <br> <br>-Fresh air, wind, air temperature and humidity of <br> <br> - Filter blockage alarm <br> <br> - Fan start .stop status <br> <br> 2) through the DDC controller of prewritten logic program, the system can do the following chain function.-Installed at the entrance of fresh air and fan chain. When fan is stopped, the fresh air door full .off. - Electric regulating valve and fans start chain. When fan is stopped, the electric regulating valve is also closed.-Fan and stopping State is used for detection of differential pressure switch. When the fan is powered fan on either side of the differential .pressure exceeding the set value, the differential pressure switch in the normally open contact closure, the signal sent to the DDC controllers, system control program is put into operation immediately. <br> <br> 3) through the mobile detector can spot extraction and .modify the DDC digital controller of any data, such as <br> <br>-Sensor detection range <br> <br> - Control parameters, including input to output, etc. <br> <br> 4) through a serial interface .on the DDC and network controller connected to a central monitoring system of the most basic monitoring unit. <br> <br> II cold station control <br> <br> From the frozen in the engine room the network controller and digital controller, DDC .substation by internal prewritten software program to control the number of water chillers and stopping and starting and stopping the device in the chain. <br> <br>-Measurement of chilled water supply and return water temperature and flow, so the actual calculation of cooling .load of air conditioning. <br> <br> - According to the actual cooling load to determine the number of cold water unit turned on, so that the best power-saving state. <br> <br>-Cooling water temperature controlled cooling .fan stops. <br> <br> - The device open / stop the program linkage: <br> <br> (A) start: cooling tower fan I cooling water pump, frozen water pumps, chiller. <br> <br> .(B) stop: chillers, cooling water pumps, cooling tower water pump -). <br> <br> (C) when one of the frozen water / cooling water pump fails, the standby pump will automatically vote. <br> < .br>-Measurement of frozen water system for water mains dropout control the bypass valve of the opening, maintaining the pressure differential. <br> <br> (1) chiller control <br> <br> The central control system for monitoring the temperature .for / backwater. Press the program restart / shutdown chillers. Depending on the system of supply / return water temperature through local controller (DDC) on temperature reset and load restrictions, etc. <br> <br> (2) cooling fan control < .br> <br> The central control and monitoring of cooling tower water temperature and control the pump stops. <br> <br> (3) of the cooling water pump / control of chilled water pumps <br> <br> According to the .freezing point of control program restart / stop pump overload alarm record to the water flow. <br> <br> III central station monitoring function <br> <br> To WindowsNT platforms, using the industry standard application software, distributed control system, L2 .network structure, culture, graphical user interface to monitor the operational status of the entire system, providing on-site photographs, process flow diagram (such as the air-conditioning control system), real-time graphs, monitoring points table, draw a floor .plan to image intuitive dynamic graphic display devices. Draw a floor plan or flowcharts and inlaid with dynamic data, display the monitoring point status, provide modify parameters or issue directives for the operation instructions. <br> <br> Available in various ways to view .the device status, such as through the floor plan or flowcharts, adoption of the drop-down menu or function keys for frequently used functions to manipulate, to click the mouse to view per-refinement and equipment status and related parameters. <br> < .br> Control functions: <br> <br> At the central station through the graphics operations you can perform a manual control site equipment, such as the device ON / OFF control; by selecting the action can be run as settings, such as selecting .a field manual or automatic operation mode; through switched menus can easily modify the process parameters. <br> <br> On the system's operation permissions have strict management to ensure the safe operation of the system. The operator to pass the identity of the means .of identification and control. Operators under different identities can be divided into the low to high 5-10 security management level. <br> <br> Advanced alarm function: <br> <br> When the system fails or on-site equipment failure .and the monitoring of parameters with the audio, generate alarm signals, alarm signals always appears at the bottom, the display as sound and light alarm, the operator must confirm the alarm signal to unlock, but all the alarm number will log to the alarm summary .table for operations personnel to view. Alarm is divided into four priority level. <br> <br> Alarm to set the alarm to print, you can also print on time or at any time. <br> <br> Integrated management features: .<br> <br> On a study and analysis of the long-term value, should be saved data, the establishment of a historical documents database: uses the popular universal standard relational database software package and the hard disk as mass storage building databases, .and forms the graphs, and other display or print features. <br> <br> Provide a summary report as a system running status monitoring, management, evaluation, further optimize operating parameters and as a basis for device management automation, such as energy use .summary reports, records of daily, weekly, monthly, all kinds of energy consumption and integrating value, to provide the basis for the economical use of energy; and if the device running the run-time, start and stop times summary report (difference between .various devices respectively), equipment management and maintenance. <br> <br> Provides a graph of time program plan, the plan can be fixed by the calendar, making building equipment schedule. Available by week, by DistrictDomain and by calendar and holiday schedule .. <br> <br> IV. building automation system commonly used equipment <br> <br> (1) sensor <br> <br> The sensor-controlled the first device in the system, it has a direct and linked to the .measured object. It makes sense to be logging parameter changes, and issues the corresponding signal. In the select a sensor typically has three requirements: high accuracy, high stability, high sensitivity. <br> <br> 1. temperature sensors: building engineering .main contact temperature sensor, such as RTD, thermocouple, PTC Silicon sensors, etc., as a result of temperature measurement components and medium need adequate heat, measurement usually associated with time delays. If the 0 ° c, Pt1000 when resistance is 1000 Ω ., with temperature resistance is reduced, sensitivity, generally within 3 ~ 4 Ω / K, response time is generally 15 to 30 seconds. <br> <br> 2. pressure sensor: commonly used electrical type pressure sensor, pressure will be converted to .the change in resistance, inductance and other electrical volume changes for indirect measurement of pressure. Commonly used pressure differential switch, gauge pressure sensor, pressure sensor, etc. <br> <br> 3. flow sensor: commonly used is the electromagnetic flowmeter, .known by Faraday, motion in a magnetic field and magnetic flux of superconductors in incising have induced electromotive force, the EMF and fluid volume flow linear relationship. <br> <br> 4. humidity sensor: for measurement of indoor air relative humidity. < .br> <br> 5. liquid level sensors used to control the water tanks, reservoirs and other lower level of the ceiling,. <br> <br> (2) actuators <br> <br> In the automatic control system, which .accepts controller output control signal, and converted into linear displacement or angular displacement, to change the valve flow cross-sectional area to control the inflow or outflow of accused of materials or energy, in order to achieve automatic control of process parameters. <br> .<br> 6. air-valve actuators: used to control the installation in the fresh air, back to the Tuyere valve can be switch control, may also be opening control. Actuator equipped with universal clamping fixture, directly in the air valve drive shafts .with manual reset button, the failure can be manually adjusted. According to the size of the duct cross-section may select a different button moment actuator. <br> <br> 7. pipe valve actuator and valve for use with switching and adjustable switching .two, diameter, in General, and heating station is used to control the system process pipeline of on and off, to switch between the different operating modes; adjustable is mainly used for control flow, in air conditioning units, according to the controller of temperature .and humidity control back to the water of the set value and the flow of steam humidification, humidity is maintained at the set value. <br> <br> (3) field controller (DDC) <br> <br> DDC is used to .monitor and control system for electrical and mechanical equipment of the controller, it is a complete controller, should have the hardware and software, can be done independently from the network or other controller failures. According to the different types of monitoring points provide control requirements and .the number of controllers. Each Department has the DDC is 10-15% of the number of expansion or allowance. <br> <br> (1) controller components comply with the following requirements: <br> <br> <br> A .) in 32-bit or 16-bit microprocessor programmable DDC <br> <br> B) can be separated from the central control hosts run stand-alone or networked capability <br> <br> C) has power module <br> < .br> D) with communication module <br> <br> E) have LED in template DDC display each digital input, the output changes state of real-time. When electric power outage, the DDC's backup battery can ensure RAM data in 60 days .without losing. <br> <br> F) when the foreign supply again, without manual intervention, DDC automatically resumes normal operation. <br> <br> G) when the DDC stored data when abnormal lost, users can spot standard serial data .interfaces and the data through the network operations will be rewritten to the DDC controller. <br> <br> H) operating procedures and DDC applications are written in a high-level language using PPCL. <br> <br> I) preparation of .the DDC, modifying the program can be in Central station or by a laptop. <br> <br> J) DDC in electric fault, while backup battery is lost, can store its due process. <br> <br> DDC's gathering K .) accuracy and precision of the sensor. <br> <br> L) work environment: temperature: 0 ° to 50 ° c, relative humidity: 0-90% <br> <br> Power supply: AC220V M), ± 10 .%, 50HZ. <br> <br> (2), DDC offers the following features: <br> <br> Scheduled stop Adaptive restart / shutdown <br> <br> Automatic amplitude control demand forecast control <br> <br> .Event control scanner control and alarm handling <br> <br> Trend records full communication ability <br> <br> (4) central monitoring station <br> <br> Central management station system consists of a PC host, color large screen monitors .and printers, is the core of the BAS system, which is directly connected to the can and Ethernet. The entire building is monitored by the electrical and mechanical equipment are all here for centralized management and display, built-in working software is supplied to the .operator drop-down menus, interactive, animated graphics, providing users with a very good, easy to learn interface, simple operation, the operator without any prior knowledge of the software, you can pass the mouse and keyboard operation management of the entire control system .. <br>.