Common equipment for building automation

Sensor is the main equipment in automatic control system, which is directly connected with the measured object. Its function is to feel the change of measured parameters and send out corresponding signals. There are generally three requirements for selecting sensors: high precision, high stability and high sensitivity.

1. Temperature sensor:

Main contact temperature sensors used in building engineering, such as thermal resistance, thermocouple, PTC silicon sensor, etc. Because the temperature measuring element needs to exchange heat with the measured medium, it is usually accompanied by time delay. For example, the resistance of Pt 1000 at 0℃ is1000Ω. With the increase of temperature, the resistance decreases, the sensitivity is generally 3 ~ 4 Ω/k, and the response speed is generally 15~30 seconds.

2. Pressure sensor: commonly used is electric pressure sensor, which converts the change of the measured pressure into the change of various electric quantities such as resistance and inductance, so as to realize the indirect measurement of pressure. Commonly used are differential pressure switch, gauge pressure sensor and static pressure sensor.

3. Flow sensor: commonly used electromagnetic flowmeter. According to Faraday's law of electromagnetic induction, induced electromotive force will be generated in a conductor that moves in a magnetic field and cuts the magnetic field lines. The induced electromotive force has a linear relationship with the volume flow of fluid. If modified, ultrasonic flowmeter can also be used to facilitate installation and maintenance.

4. Humidity sensor: used to measure the relative humidity of indoor air.

5. Liquid level sensor: used to control the upper and lower liquid levels of water tanks and pools.

In the automatic control system, it receives the control signal output by the controller and converts it into linear displacement or angular displacement to change the cross-sectional area of the regulating valve, so as to control the material or energy flowing into or out of the controlled process, thus realizing the automatic control of process parameters.

6. Air valve actuator: It is used to control the air valves installed in fresh air and return air outlets, which can be opened and closed with controllable opening. The actuator is equipped with a universal fixture, which can be directly clamped on the valve drive shaft, and is equipped with a manual reset button, which can be manually adjusted in case of failure. According to the size of the cross section of the air duct, actuators with different button moments can be selected.

7. Actuator of water pipe valve: It is used together with the valve, and there are two types: switch type and adjustable type. Generally, the switch type has a large caliber, which is used to control the opening and closing of process pipelines in each system and the switching of various working conditions in cold and hot stations. The regulating type is mainly used to control the flow. In the air conditioning unit, the return water flow and steam humidification flow are controlled according to the temperature and humidity set value of the controller, so that the temperature and humidity are maintained at the set value. DDC is a controller, which is used to monitor and control the electromechanical equipment in the system. It is a complete controller with appropriate software and hardware, which can run independently and is not affected by network or other controller failures. According to different types of monitoring points, provide controllers that meet the control requirements and quantity. Every DDC has an extension or difference of 10- 15%.

(1) The controller shall meet the following requirements:

A) programmable DDC with 32-bit or 16-bit microprocessor

B) Have the ability to operate independently or network without a central control host.

C) having a power supply module

D) having a communication module

E) DDC has a template LED to display the real-time change status of each digital input and output point. When the external power supply is cut off, the backup battery of DDC can ensure that the data in RAM will not be lost for 60 days.

F) When the external power supply is re-supplied, DDC can automatically resume normal work without manual intervention.

G) When the data stored in the DDC is abnormally lost, the user can rewrite the data into the DDC controller through the field standard serial data interface and network operation.

The operating program and application program of DDC are written in PPCL high-level language.

The compilation and modification of DDC programs can be carried out in the central station or through portable computers.

J) When the external power supply is disconnected and the spare battery is lost, DDC can store its proper program.

The acquisition accuracy of DDC matches the accuracy of the sensor.

L) Working environment: the temperature is 0 to 50 degrees and the relative humidity is 0 to 90%.

M) power supply: AC 220v, 10%, 50hz.

2)DDC has the following functions:

Timed Start-Stop Adaptive Start-Stop

Automatic amplitude control requires predictive control.

Automatic event control, scanning program control and alarm processing.

In recent years, the future buildings are considered to be full of all kinds of intelligent devices. The sensors, actuators and valves in the building control network are all intelligent, and the infrastructure of the building can seamlessly connect the data network and the control network to form an integrated building network. The whole building network will become a model of building control in the future. In the 1990s, people gradually formed a new concept of information transmission in building automation: intelligent devices-sensors and actuators constitute an autonomous control environment, that is, intelligent temperature sensors, light switches, curtains, elevator buttons, card readers and so on. Network-A new generation of smart devices can seamlessly connect various networks, such as the Internet, corporate networks or build wide area networks and local area networks. Global networking-With the development of networks, devices and systems, users can remotely access anywhere on the intelligent building network at any time in the world. The whole concept of building a network is no longer an expectation for the future, but is happening today. Manufacturers providing intelligent devices, subsystems and systems are growing exponentially. This driving force mainly comes from the owners, who demand higher and higher degree of integration of buildings and properties, which is also reasonable. Because today, intelligent products of building automation subsystems, such as access control, closed-circuit television, elevators, air conditioning, heating and ventilation, security and fire protection, have come out. Although many intelligent products are gradually updating the building subsystem, the real overall building network system is still rare. On the one hand, vendors are completely close to open systems, but on the other hand, they are afraid of market changes brought by a standard network communication protocol and a truly open structure, which limits the development of interoperable products. Big companies are willing to maintain the status quo because they have vested interests. Many large factories apply L0NWORKS technology to the underlying devices because they find that L0N WORKS platform, an economical and effective technology, can realize the communication between devices in their closed systems, but they are only willing to do so. In the 1960s and 1970s, some giants in the computer industry, such as IBM, Burroughs, Control Data, Sperry, NCR and Honeywell, monopolized the computer market. Their equipment is huge, closed and expensive. In 1970s and 1980s, a number of new computer companies appeared, such as DEC, Data Geheral, Tande and Wang An Computer. The computer products of these companies are relatively distributed, but they are still expensive closed master-slave systems.

In 1990s, another group of computer companies replaced the leading position in this industry: Compaq, Dell, Gateway and Hewlett-Packard. These new companies can achieve such results because their products are completely open, cost-effective and flexible. With the increase of sales channels, manufacturers can cut costs and expand the market to get more profits. Today's building automation industry has many similarities with yesterday's computer industry. The traditional building control system is also closed, usually purchased from a company and installed by them. Because this system is a master-slave control structure, the installation and maintenance costs are high, and the future increase, decrease, modification and maintenance have certain limitations. Any subsystem level integration needs expensive gateway hardware and professional editing programs to complete. Unfortunately, many control system manufacturers are unwilling to provide a truly open platform. What end users want is an open set of equations, excluding those expensive, exclusive and closed templates and central controllers, as well as the corresponding complicated wiring, control procedures and maintenance. Today's control equipment manufacturers want to integrate their expensive gateways (achieve interoperability). Although these gateways can make subsystems interoperate to a certain extent, they restrict the communication between terminal devices and make the whole system complicated. Intelligent router can solve the above shortcomings. The router makes the channel transparent and can access the terminal equipment on the channel from anywhere. Routers improve the reliability of the system and provide enough flexibility for upgrading, changing and replacing. The working mode of this router is only logical isolation in the network, not physical isolation. When our control industry adopts a truly open system, owners and property managers can enjoy the real benefits of integrating a building management system from products of different manufacturers: free choice of products, technologies and services with the highest cost performance; The cost can also be amortized over the actual life of the product. Development and installation of open control network The related companies provide the basic system-level modules of the open LONWORKS control network, mainly for OEMs. Products include: development tools, Lon Talk (communication protocol), neuron chip, transceiver, network interface, network operating system and network management software. These series of products can enable OEMs to directly gain the benefits of LONWORKS network without redeveloping the technical core of open control network. They can concentrate precious human and material resources to develop control equipment and systems, improve the added value of products and reduce the development and production costs. The products provided to system integrators play a key role in completing a highly distributed and interoperable control scheme. Therefore, Eche Company correspondingly provided a set of Lon Point system products for system integrators. These products enable system integrators to integrate L0NMARK products provided by different manufacturers to complete a complete control solution. This solution can replace the central controller mentioned above and assign the control algorithm directly to I/O devices.

Echelon's Lon Point interface module can not only replace these central controllers, but also be used by system integrators to connect traditional old devices without neuron chips and transceivers to Lon Works networks. The mental element chip in LonPoint module can directly process the signals of sensors and actuators. Compared with the complex central controller, these LonPoint modules with easy installation and simple programming have great price advantages in terms of price, wiring work and maintenance. Echelon foresees that in the field of building automation, related companies will push the market to an open and fully distributed network control system based on the interoperability of LONMARK. To achieve this step, manufacturers are required to disable those exclusive central controllers and gateways, so as to reduce the cost of equipment, installation and life cycle, thus reducing the system cost. Many manufacturers are still skeptical about "open systems". What they care about is whether the market can really grow rapidly after opening up. In fact, they worry too much. After the opening of the regulatory field, the market will certainly expand rapidly, and then producers can truly achieve the degree of small profits but quick turnover. LONWORK Interoperability Association and its more than 240 members are committed to promoting a truly open building automation market. Association members come from manufacturers, integrators, owners and end users. The work of the association includes developing interoperability standards, certifying products and promoting markets. Enterprises in the construction industry are fully networked. With the rapid development of enterprise data network and Internet, it is more and more urgent to connect the control network of enterprises to TCP/IP. Routers are used to connect different channels, not gateways. The working principle of this "tunnel" router is to encapsulate the working information of L0N in a TCP/IP packet and send it to the TCP/IP network. Because the system with this structure is an integrated network, all points are transparently connected, which makes the installation, monitoring, diagnosis and maintenance of the system very convenient. In other words, network tools can work on other nodes anywhere on the network.

The new generation router can connect the channels on four NW0RKS networks transparently and seamlessly to the Ethernet trunk network, or directly to computers with Ethernet cards. The result is a powerful and consistent LONWORKS building automation system, which connects the building property management software system with all intelligent nodes. This integrated network structure greatly reduces the life cycle cost of the system and can complete many solutions that are now considered impossible. In order to realize the application of this IP (Internet Protocol) connection mode, related companies are working closely with Cisco to develop and launch products that meet the market demand. Now a new generation of building automation products have entered the market, and companies such as Siemens, Honeywell, Johnson & Johnson and Haisai are constantly seeking technological innovation and breakthrough. The building system is truly open, which requires owners, designers and integrators to propose truly open and interoperable new products to manufacturers. Without this power, the manufacturer of the controller will continue to provide old products. The industry needs to establish new specifications, formulate LONMARK interoperability, design the architecture of peer-to-peer plane, and use network tools based on LNS platform without gateway.