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References / Concepts

There are only two basic approaches to automation and dispatching of buildings:

  • Bottom-up, which means integration of separate elements of local automatic equipment into a system;
  • Top to bottom, which provides application of a uniform, preselected, hardware-software platform for automation and the subsequent dispatching of a building.

Both approaches have specific advantages, disadvantages and scope of application. Besides, separate implementation of each of them at specific project is rarely managed.

The first approach consists in maximum use of fabricated parts of automatic equipment. Manufacturers of engineering equipment, such as boosting pump stations, draw-in air systems, offer delivery of their equipment together with turnkey control systems. Turnkey systems are supplemented with non-standard elements and are integrated with them into unified system.

This approach is fixed in the Russian standards (SNiP for dispatching) and is optimal to certain technical systems density. Dispatching consists in transceiving of discrete signals, dispatching boards are made on relay basis.

Advantages of this solution:

  • low price of the project;
  • simplicity and good layout of schemes

Competent electrician is capable to perform assembly and debugging of such system.

Disadvantages:

  • large scope of control cables laying;
  • absence of safety alarm, failure alarm means that work of any system has already stopped;
  • extremely complicated enhancement;
  • low reliability;
  • full absence of system self-test;
  • result of two last factors Ц in order to support system in operable condition qualified service and constant performance of great scope of diagnostic and commissioning works are required.

Maximum configuration of engineering equipment of a typical building which is advisable to dispatch in a like manner, as a rule looks the following way:

  • draw-in air systems or combined extract-and-input ventilation systems (to 5 units);
  • exhaust ventilation systems (to 8 units);
  • smoke control systems (to 3 units);
  • overpressure systems in fire-prevention platforms and elevators (as a rule one);
  • fire-retarding valves (there can be significant amount, to 70 units);
  • antismoke valves (to 3 units);
  • fire-prevention boosting pump station or a bypass valve of metering station;
  • boosting pump station of domestic water supply.

With larger quantity of engineering equipment, such solutions become technically pointless, since reliability of dispatching system decreases insomuch that issued information loses actuality, sometimes failure frequency of dispatching system can exceed failure frequency in engineering systems. It is also economically inadvisable, since even without operational expenses cost of unstandardized boards and a great amount of cable outweighs expenses for dispatching systems creation on a "top to bottom" basis.

The second approach consists in refusal of automatic equipment delivered by engineering equipment manufacturers in favor of building automation system creation constructed using constituent parts of one of the well-known automation system manufacturers. There are enough solutions in the market offering integrated systems of automation and dispatching of buildings. All of them consist of:

  • specialized SKADA-system;
  • data transmission network;
  • low-level controllers;
  • detectors and executive mechanisms.

This system being installed in a building, covers all engineering systems. The structure of such system of automation and dispatching of building consists of boards with powerful dispatched controllers established in technical premises Ц ventilation chambers, pumphouses, furnaces serving all engineering equipment located in them. Controllers of these boards receive data directly from detectors and operate engineering system mechanisms. All controllers are directly connected with workstation of dispatcher for common interface. The structure of such dispatching system is the most simple of existing ones. The exception is made by pump stations, boilers, refrigerators (chillers) and some other specialized aggregates having built-in automatic system providing complicated algorithms of management or safety function. Manufacturers of such equipment, as a rule, develop their unique interfaces and that is why each automation manufacturer has the whole "collection" of special interface cards for connection to his dispatching system.

Advantages of Top to bottom solution:

  • minimum time of dispatching system creation - network creation, data display on dispatching computer, record-keeping of events is carried out by SKADA-system adjustment;
  • high reliability of information delivered to the dispatcher, all information of local controllers is automatically visible for a workstation;
  • automatic record-keeping, trends and archives keeping of both engineering systems work, and actions of operators;
  • resource-related recording function and maintenance programming;
  • minimum costs for dispatching - just one cable bypassing controllers in a sequence or ringed manner;
  • practically unlimited extendability of controllers quantity in a network and as a rule high expansibility of controllers, range of network laying sufficient for the big buildings and high rate of data transmission;
  • built-in functions of self-test, network self-configuration, high level of protection against noise waves, network survival at separate controllers failures, as a rule, possibility of "hot" connection of controllers to network;
  • continuation of controllers work at network failure;
  • possible departure from automation systems creation concerning separate engineering systems to territorial principle, for example, to floor automation on tall block buildings, when one controller operates elements of all engineering systems located on a floor;
  • simplification of maintenance service and operation of automation and dispatching system, since the system created using the equipment of one manufacturer has minimum assortment of constituent parts;
  • possibility of system transfer for service to company service engineering centers network.

Disadvantages:

  • additional time and expenses for automation project development (instead, dispatching system appears to be practically free supplement);
  • longer period from the beginning of engineering system assembly to its start-up, since not one but two companies are involved;
  • higher level of technical supervision and mutual support organization between contractors are required during installation works performance.

At dispatching of the largest buildings no other solutions can be compared by simplicity, reliability and, as a result, economic efficiency of engineering systems dispatching.