】 【Weak current college building automation and HVAC design in DDC controller configuration.

Summary: DDC controller reasonable configuration is a design of building equipment automation, DDC controllers of critical allocation based on the main control objects-air conditioning equipment, article on air-conditioning design and DDC controller configuration guidelines and monitoring principles made some comments.
1 on the design of air conditioning
A successful building automation design must meet the requirements of the air conditioning design, on-site application requirements with reliability, security, economy, flexibility, energy saving, Festival, extend equipment life, this is done by various professional interaction, mutual understanding and to create conditions for the realization of design goals.
1.1 multiple chiller configuration should give priority to the use of farm machinery, farm pump, Group Tower system
This way you can run the flexibility to meet asymmetric equipment failure system normal operation requirements. For example: when 1 # 2 # chillers, cooling tower fails, you can launch 2 # 2 # chillers, (1 #) frozen pump, 2 # (1 #) cooling pumps, cooling tower 1 #.
1.2 variable flow system for backwater by-pass valve installation location
Currently, the project see variable flow air conditioning system, air conditioning design for 2 and 2 more than the basic engineering, water chillers are cooling load calculation method number control chillers, cooling load calculation accuracy is essential, otherwise not be able to achieve control objectives.
1.2.1 water separator has 2 and 2 + water system
When water separator has 2 and 2 more minutes in the water system, load and return water dry pipe fitted flowmeter, flow rate multiplied by the difference in load and then take the backwater to spot real constant cold. Actual cooling capacity and single-SML cold quantity comparison, then decide to increase or decrease the number of table water chillers. But in the scene and a lot of information, you can see that the by-pass valve installed in a water separator and set water, flow meter is installed in the backwater side by-pass valve. In other words, the flow measurement the flow meter is a load of water and bypass water and, while water thermometer detects a load of water and temperature of water mixed with bypass. Thus to calculate cooling loads error is too big, therefore, it is recommended that the air conditioning design in consideration of a building control engineering, backwater by-pass valve should be frozen pump for water and even install on both sides of the pipe Division, and leaving the water from the set to a value of 15 times the return pipe diameter of horizontal line segment requirements (load backflow section) so that the temperature on the side for the backwater also installed in the backwater straight pipeline, thus calculated the cooling load can guarantee its accuracy.
1.2.2 without water separator or only one water user
Chiller works without water separator or only 1 minute of water users, this problem does not exist. Simply ensure that the flow meter diameter of 15 times the return pipe and horizontal line segment to install such conditions.
1.3 multiple heat transfer system works to simplify system
Traditional multiple heat exchanger system design, each subsystem has its own independent expansion water tank and fill the pump so that I/O points increases, increasing the capacity of the DDC controller or the controller number. If you are installing from a technology perspective, reduce expansion water tank and fill the water pump, both to meet the system requirements, I/O points and the Professional are reasonable. I have seen a project with air conditioning (cold and hot) heating hot water boilers, geothermal, wind curtain 4 system with 2 expansion water tank 8 sets up pumps, after reconstruction 2 expansion tank 2 fill pump. Enable I/O point significantly reduce operating costs, system, system more reasonable.
1.4 group, group of pump, Group Tower system for chillers number control must be equipped with electric butterfly valve
A group of machines, social systems, Group Tower on chillers number control, the chillers evaporator and condenser and sailor valve must be open valve State running to ensure that the cooling load increases automatically added chillers satisfy cooling load. Because of the power-on, outages have water through water chillers to load, and this water as mixed water, mainly for evaporator heat of cooling water, another part without the heat of the water and water mixed to load, so that the chilled water quality degradation, for which should be in the evaporator and condenser outlet with electric butterfly valve to ensure water quality.
1.5 and even the heat exchanger system, once installed electric butterfly valve for heat exchanger number control
Heat exchanger capacity and number is the largest HVAC professional press load condition, but in actual operation, the maximum load of time is very short, often in load rate is not high to run under the conditions, in particular, office buildings, building, buildings, and just generally work system, staff and rest day after work, the building is basically a low-temperature operation support system, therefore, the number of heat exchanger reduces to 1, such a heating system heat load reduction, or even a water temperature can also be set according to their own conditions change, thus saving energy, temperature, water-water heat exchanger in a backwater side retro-electric butterfly valve to achieve control (air-to-water heat exchanger in a gas pipeline installation).
1.6 North frozen pumps, cooling pump does not have to install an alternate pump
The author has been 6 years participate in Changchun two installed air conditioning of buildings run management. The frozen pumps, cooling pump, are more than chiller one as a standby, practice water chillers are not all at the same time. And pump are belong to summer, winter shutdown, the load is the maximum load of 30% ~ 70% of the time (see table below), maintenance and repair of low load and can be used in winter, so install alternate pump not very meaningful. Frozen pump should be separated with heating circulation pump. A group of machines, social systems, Group Tower, the application is very flexible.
1.7 provides electric control valve at both ends of the pressure difference parameters such as
Electric control valve diameter selection is critical, both ends of the pressure difference is an important basis for selected, select the appropriate diameter ensures circulation capacity, it may appear the valve to open degree maximum or minimum aperture is still not meeting regulatory requirements. Therefore, the design should provide electric regulating valve installation location, technology pipes, media temperature, nature, pressure, pressure difference, and so on.
1.8 air conditioners, number of outdoor air machine
DDC Controller General conditions on siteCondition 2 as control conditioner or new fan configuration, the air conditioner, the more fresh air machine number, DDC controller and the sensor, the more even floor control investment than air conditioning. For example, C building standard layers each layer selection 4 5000m3/h air conditioning (hot and cold water valve and humidification valve) each layer selection 2 MEC-200 controller (four sets of devices drives, valves, sensors), each floor control more air conditioning equipment costs more 2.5 million. If a layer with one or two layers with a conditioner, DDC controller remains one can control two air conditioning equipment, drives, valves, sensing the number with the air conditioning equipment and reduce infrastructure costs, visible. Therefore, how to consider the air conditioner and new fan number configured is an important factor in BAS investment.
1.9 retro bypass valve
Chilled water system under the control of needs in different parts of the installed electric butterfly valve and electric control valve, for the maintenance of treatment failure does not affect the normal operation of the system, should be considered in the design of the air-conditioning by-pass valve design, as well as electric butterfly valve and electric control valve with horizontal and vertical distance of the installation space.
1.10 blowers
In many engineering and underground floors blowers in fire and do blowers (meet the specification requires the amount of 50 per cent of the exhaust air), the Northern cold areas in order to prevent winter freezing and air-conditioning equipment, water systems are in use with back to the air valve, air supply valve using blowers insulation valve closed, air valve in the open cases run manually. This system is in need of fresh air valve fire, open air valve should close (or they may be back to the wind out of smoke), while fresh air valve is controlled by the floor, fire control and cannot control, and in case of floor control does not work well, they could not supply air. The authors suggest that this kind of system air supply design two fresh air valve, 1 valve controlled by the building have source control, another valve by fire active automatic control. Competent approach still as 1 Road, return air valve to control the fire. Forced draft fan deng? stop because sodium is passive control, building control and fire can control, to building control and fire protection separate each completed its control function?? br>
1.11 heat load measurement
II control system, you can use measurement of flow and cooling load for the return water temperature difference calculation of cooling load, use the same formula to calculate the heat load. But it needs to heat exchanger secondary water fittings in frozen pump and the water supply pipeline and the junction for backwater by-pass valve, heat exchanger secondary return pipe next to frozen pump and even return water pipeline and the junction for backwater bypass valve (at this point the flowmeter installed upstream of the confluence point).
1.12 chiller number settings
The author according to years of operating experience that cooler set 3 more reasonable. If number is more than 3 covers an area of large, complex, multiple I/O number, floor, control costs, while at the same time usage is low. 2 computer running not flexible, with only 2 types of operation, is not conducive to saving energy. 3 select 1 small (total cooling capacity 1/4) 2 large (total cooling capacity 3/4), total running mode. Running flexible basic refrigeration efficiency can work in running highly effective area, to save energy.
1.13 air-conditioning unit return air pipe set
Some projects use ceiling air-conditioning unit, the design of static pressure chamber with ceiling do not specifically set the return air ducts, in use return air temperature detection control sokki no installation location, optionally placed in the suspended ceiling, practice has shown that this kind of operation performance is poor, cannot meet the technological requirements. Experience from running a loop set on the pipeline more reasonable, the layout of the floor dedicated unit, when the room adjacent to use places no return air ducts, but need to go back to the air outlet pipe to the adjacent wall ceiling set at the return air 100 pages.
2DDC controller configuration guidelines
2.1 device number centralized place
Cooling stations, boiler houses, heat exchanger stations, substations are device central place, shall select bulk DDC controller. For example: Honeywell, Excel5000, XL-500, Siemens600, MBC. XL-500I/O point 128, MBC, I/O module 80 (each I/O module is 1 or 2 or 4 points), which can be extended.
For example, a project to bid the book: XL-500 analog and digital input and output when mixed with 650 $/point, pure digital input and output of 400 Yuan per point. XL-50 analog and digital input and output when mixed with 850 RMB/point (the only controller unit price, not including sensors and actuators).
From the economic conditions taken into account by the visible, conditional use bulk of DDC controller is reasonable.
2.2 process-related equipment requirements, configure the same controller
According to the process-related equipment needs to be configured the same controller, this makes it easier to debug and run (monitoring). For example: the same cold station controller to monitor, control, management, except for chillers, cooling pumps, cooling pump, fill the pump, including from cold station installation distance of cooling towers, expansion tank. Heat source system boilers, boiler circulation pump, boiler feed pump, heat exchanger, secondary heating circulation pumps and boiler related exchanger, circulation pump, water pump, expansion tank (including a different installation location) also belong to the same controller.
2.3 press run time and season configuration controller
According to the above configuration, the device is running, in summer, winter outage winter and summer downtime, year-round operation. The following analysis of general engineering equipment operating season.
Summer operating equipment: chillers, cooling pumps, cooling pumps, cooling tower, dedicated cooling station with variable power distribution equipment.
Winter running equipment: heating with hot water boiler, heating with heat exchangers, boilers, hot water circulation pump (a), the heating circulation pump (second), fuel oil boiler feed pump, boiler feed water pump (in addition to the works of domestic hot water steam boiler heat is used for the quarter, the other for winter operation), geothermal, Sirocco screen with heat exchanger and related circulation pump, water pump, expansion tank, etc.
Year-round operation equipment: domestic hot water steam boiler and steam boiler feed pumps, softener,Softened water, condensate tank, condensate pumps, air conditioning repair for air conditioning pump, expansion tank, air conditioners, fans, fan-coil line), domestic hot water with a heat exchanger and circulation pumps, pool heaters, circulation and filtration pump, DOSER, water supply and drainage equipment, exhaust fan, elevators, lighting, power supply equipment, water separator, set water, backwater bypass valve (means heating areas), pool, living with fire and water tank.
You can run all year round in a controller, this makes it easier to press the seasonal maintenance controller, system operation is not affected.
2.4 system 2 and above address bus configuration
2.4.1 no network controller
Some products central station and field controller DDC newsletter only with converter in no network controller, for example: Excel500 central station by xpc-500 or Q7055 converter to connect 3 C-Bus bus, each can add 29 stand DDC controller. SiemensS600 central station by 538-675 exchanger can connect 4 BLN bus, each can add 100 DDC controllers, controller requires communication between work, in conditions of placement in a controller, to accommodate the same C-Bus or same BLN bus, so you can ensure that communication is not affected by the workstation failure and still be able to meet the communication requirements of the process. For example: cold station controller and expansion tank, cooling tower controllers are not on the same controller, but the two controllers should hang on the same bus.
2.4.2 a network controller
Some products central station and field controller DDC newsletter intermediate need to install the network controller. For example: Johnson products central station and DDC controllers will need to install the network controller, which exists in different network controller DDC controller under hanging in any 1 network controller failure circumstances cannot, therefore, such a system work in communication requirements should be housed in the same network controllers hang bus.
2.5 press monitoring object to configure the installation locations
When the monitored object is set to installed across the room, adjacent room and adjacent floors, and is not related to each other mutually independent should fully use DDC controller capacity arrangement in a controller, if you have richness I/0 points, wiring length and to the extent permitted in the product, and is independent of unwanted and other points of DDC newsletter can be arranged in a controller. (SiemensI/O line up 230m, DI/DO: 14AWG-22AWG, AI/AO: 18AWG-20AWG).
2.6DDC controller after comparing different configurations, and then do recommend programmes on project basis to monitor, control, management, equipment and distribution locations, on-site requirements, using different controller configuration options, you need comprehensive comparison to decision recommended scenarios. For example, an engineering equipment distribution, functional, monitor content management requirements has been established to consider the conditions, the use of DDC configuration XL-500 centralized configuration, or with the bus expansion through Lon-Bus XL-500 programme, or a combination with XL-500 and XL-100. When using MBC extended programmes or MBC and MEC combination programme, even there are also multiple scale and MEC MEC configuration scenarios, you need to do some work, from the price-performance, comprehensive comparison with maintenance and do recommend programmes.
2.7DDC controller monitor target for air conditioners, a new fan of configuration high-rise buildings, many of the same functions, the same plane of floors, air conditioning equipment layout is the same horizontal position on the same device number. DDC controllers generally choose 1 medium controller 2 conditioner or fan, or a device number often should use large controller. This configuration uses a different controller to monitor, control, management towards the South and North more reasonable. So in the preparation of the post, downtime, temperature setting is on (toward) by groups, and even the floor and towards the group preparing the schedule to run more convenient.
3DDC controller to monitor, control, management principles
DDC controller is building equipment automation, the most important component, it can compile stored procedures, make the device according to the procedure runs, you can capture devices, various preparation, operation, transmission failure status to the workstation, and accept the various command workstation timely transferred to the device and executing agencies to complete the command, it can be seen DDC controller in important role in the system.
DDC controller for building air conditioning ventilation system, the heat source and switching systems, refrigeration and cooling systems, distribution systems, public lighting, elevator and escalator systems for monitoring, control and management. But in design to the implementation of national, sectoral ministries procedures, specifications, requirements, the following talk about the views of the author.
3.1 and fire facilities interface
3.1.1DDC controller cannot monitor firefighting equipment and facilities belongs to fire special equipment and facilities are: water, fire fighting hydrants, spraying pumps, with exhaust smoke machine, positive-pressure blowers, fire shutter, fallout first floor elevators, fire elevator, fire elevator catchments sewage pumps, fire, emergency lighting, evacuation signage lights, emergency broadcast, power supply for fire-fighting, fire water storage tank and dedicated exclusively to high water.
3.1.2DDC controller monitoring work and fire equipment and facilities
(1) underground layer of smoke machine: usually design in typical double as exhaust fan. However, a two-speed motor single duct system, low-speed to normal working time exhaust, DDC controller should monitor. When using high speed to fire, the fire controllers monitor. Another is the dual-motor, motors, capacity, often small air motor is typical exhaust, DDC controller should monitor. Another large amount of wind and small air fan is used, when the fire by a fire controller monitoring;
(2) a basement blowers: some works will double as a fire in the basement of blower air, meet regulatory requirements by 50 per cent of the amount of exhaust smoke. This class of device DDC controlIn normal working hours should be monitored, as a blower. In fire by a fire starting and stopping the controller monitors and open dedicated outdoor air valve, close the air valve;
(3) the combined domestic and fire water storage tank or high water;
When life and fire and the cistern, the water level drops slightly higher than the fire water level signal, from DDC controller detection after low water level alarm and stop watch domestic water supply, to find causes, to the sink in water, is situated slightly lower than the overflow water DDC controllers with high water level alarm (if set water electric valve, received high signal, the water supply should be immediately shut down the electric valve), duty to find the cause. When the water level below the fire water tank, fire controllers receive low-water signal and the issue of low water level alarm signal.
When life and fire combination of high water, the water level drops slightly higher than the fire water level detection by DDC controllers, should immediately to pump water, but if the water level drop bottom-fire water level, not for living water (use of living water supply pipe installation to restrict elevation), the signal received by the fire controller alarm signal, after find reason. watchkeeping personnel When the water level of a high water tank overflowing level, DDC controllers with high water level alarm, to immediately stop the pump.
3.2 and corresponding electronic control device interface
3.2.1 elevator centrally monitor disk
In the selection of elevator central control disc project, DDC controller is not necessary to monitor the location of elevator cabin only monitors the operating status and fault.
3.2.2 no elevator centrally monitor disk
No lift to centrally monitor disk works, generally only monitors the operating status and fault alarm. To monitor the position of the box, "Beijing Desheng Guosheng information system engineering co., Ltd." binary encoder practices so that you can save a lot of DI. For example, a 30-story building will save 25 points.
3.2.3 sewage pump
General high-rise building have sewage pumps, and supporting electronic control, it is as level (supporting) automatic starting and stopping. DDC controller, therefore, should not be monitoring the starting and stopping only monitoring fault alarm, automatic State, running, or select the level sensor. But owners ordered sewage pump to explicitly provide liquid level sensors and introduced watch the terminals, and requires the manufacturer to DDC controller required contacts connected to terminals.
3.2.4 frequency live feed pump
Many projects use constant pressure variable water supply system. Basically it is supporting EFI electronic control equipment, pump starting and stopping automatically run under pressure. Therefore, DDC controller only monitoring fault alarm, manual, automatic State, running state. Simply matching manufacturer will DDC controller required contacts connected to terminals.
Reference documents
1 luyao HVAC design Khanh .HVAC. building press guide; 1996
2 pay Xiao-Ping Chong Yang air-conditioning system operation and management of Tsinghua University Press; 2001.
3 steel Pan yun. design of tall building air-conditioning; architectural press, 1999.
4HoneyWell. building automatic control system application manual; 2001
5 Siemens technology .APOGEE peak system technical manual; 2003