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EBOOK - BMS Design Guide - Comfort Control (Azbil)

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BMS Design CONTENTS Preface The purpose of this document is to help the users to understand how the instrumentation of air-conditioning system works There are various types of instrumentation systems such as electric, electronic and direct digital control (DDC) systems, which can be used to control the air handling unit (AHU) This document includes a number of examples with the emphasis placed on electronic and electrical instrumentation The Appropriate method must be selected after studying the various conditions such as how the system will be used, likely operating conditions, degree of control accuracy required, consistency of all facilities, etc Contact the Yamatake representatives for further information on actual instrumentation and design Part I Building Management System 1.1 What is building management system? 1.2 The Advantages of Building Management System Fundamentals of Automatic Control 2.1 2.2 2.3 2.4 2.5 2.6 General of Automatic Control Automatic Control Methodology Application fo Automatic Control device BMS & Automatic control design general 11 Automatic Control System Design Procedure 15 Automatic Control System Retrofit Planning Procedure 17 Automatic Control Devices 3.1 3.2 3.3 3.4 Electric Control Devices 19 Electronic Control Devices 19 DDC (Direct Digital Control) 21 Intelligent Component 24 HVAC System generals 4.1 AHU Systems 25 4.2 Chiller Plant Systems 26 Control Functions 5.1 HVAC Automatic Control details 27 5.2 Energy saving application 30 Typical Instrumentation Examples 6.1 Examples of Automatic Control System Instrumentation 35 Part II Guide Specification for HVAC Building Management System Building Automation 1.1 What is Building Management System? (4) Intelligent Building Management System The Intelligent building management system collects, stores and processes information on a variety of facilities in buildings and operating data to help building managers with maintenance control work, maintenance work, tenant billing and energy management and helps building owners with maintenance cost management For example, software is included that supports equipment ledger management, performance management, maintenance schedule management, metering and billing ⋅ Vertical integration of functions ⋅ Vertical decentralization of systems Information management IBMS Building Management System Monitoring / operation Central control Automatic control system Smoke control Automatic fire alarm Access control Intrusion monitoring Plumbing Chiller plant Air handling Power Local control Lighting (2) Building Management System The Building Management System monitors the operating status and identifies any malfunctions of the equipment in building at the fundamental level It carries out display of functions, keeps a log and operates the system It also controls system-wide facilities such as power or air handling systems For example, it features scheduled operating controls to operate equipment according to a set schedule, and power demand control to operate each facility and all equipment so that the power demand (3) Security/fire control system The security system controls access to buildings or individual rooms using a mechanized system, features intrusion monitoring to detect intruders in buildings, and issues alarms and video monitoring There are two types of access control system: using a key management box, and using a card reader These systems assure not only the safety of buildings but allow users 24-hour access The fire control system for detecting fire in buildings and for preventing the spread of fire can display alarms or stop AHU by establishing a receiver specified by laws and by incorporating the signals into the integrated BA system Elevator (1) Automatic control system The automatic control system provides continuous, sequential and energy-saving control of process values (physical values) related to air handling, chiller plant and Utilities, etc In air handling systems, control of temperature or humidity in air handling units (AHU) which carry out cooling/heating or ventilation is included In chiller plant facilities, a number of operating unit controls and pressure controls for heat pump chillers, refrigerators and pumps are included In Utilities, control of water tank level and pumps operation which supply clean water in buildings or waste water treatment are included in the automatic control system agreed with utility companies will not be exceeded The system can be upgraded to the BMS, in which the information managed by the BMS can be displayed on user's PC monitors and users can operate each facility User terminal (PC) Building Management System (BMS) is comprehensive system for controlling and managing various facilities in a building Central monitoring system monitors the operating status and errors of building facilities such as air handling, chiller plant, utilities and power facilities With the advent of computer technology and improvement in digital communication technology, the automatic control equipment of air handling can now be integrated with centralized equipment resulting in centralized monitoring and control of all the facilities in a building Centralized equipment is now called an Integrated BA System, which monitors an expanding number of facilities, from lighting, elevator facilities, fire control facilities, and security facilities such as access control or intrusion monitoring from user terminals It has also expanded into a system called a Intelligent Building Management System which controls information on the entire building and its facilities and ensures their effective operation A BMS can be classified into the following four categories ⋅ Horizontal integration of target facilities ⋅ Horizontal decentralization of system Figure Conceptual rendering of Intelligent Building Management System Building Management System Intelligent Building Facility Reservation Lift/Escalator System Fire Alarm IBMS Server Ethernet Integration Data Server BEMS Building Energy Management System BACnet IP Energy Data Server System Management Server Client PC System Core Server LonTalk Infilex ZM Paramatrix Chiller Plant Controller SAnet Infilex AC Infilex GD Infilex VC Infilex FC ACTIVAL ACTIVAL PLUS VAV BOX ACTIVAL MINI Neoplate Neopanel Intelligent Component Series Building Management Figure Sample automatic control system of air-conditioning and Sanitary facilities Building Management System IBMS Management System Help Desk Facility Management Asset Management Multimedia Public Display Security Security System OPC Server Security Data Server Data Storage Server BACnet IP Access Core Controller Wiegand Infilex GC 3rd Party LonTalk Devices Electric Lock IR Passive Sensor CCTV Proximity Card Reader Lighting System ACTIVAL CO2 Concentration Transmitter Pipe Insertion Temperature Sensors Room Temperature Humidity Sensor Duct Insertion Temperature Humidity Sensors Operator Panel BMS System Figure 3 Sample integrated BA system BACnet Devices Modbus Interface PLC Power meter Building Management System 1.2 The Advantages of Building Management System The advantages of introducing a Building Management System to users of buildings include the provision of a comfortable, safe and convenient environment The advantages to owners and managers include reduction of operating costs by means of energy conservation and labor-saving over the entire building as well as better maintenance, leading to improvement of the value of property The BMS clearly affords a variety of benefits In particular, the automatic air-conditioning control system allows the creation of the most comfortable environment for users, prevents wastage of energy by optimum control and continuously maintains these advantages Introducing BMS The detailed benefits of introduction are as follows: (1) Labor-saving, efficient management Since integration allows comprehensive control of large amounts of data, operation of building and facilities can be carried out by a smaller number of people More sophisticated management can be realized through effective use of the information (4) Ensures a variety of safety features By concentrating all information about building facilities into the central unit, you can easily identify the status of facilities, operate the facilities and take correct countermeasures in the event of power failure or outbreak of fire By integration with the security system, you can assure the safety of building users and confidential information with no loss of convenience (2) Maintenance and optimization of environment Maintains optimum thermal environment condition, such as temperature and humidity including CO2 and dust requirements, as well as lighting levels for individual users or production facilities (5) Improve convenience for building users By integrating each facility, services and convenience to individual users can be improved For example, 24-hour free safe access to buildings, simple and user-friendly setting and adjustment of temperature or operating time and identification of outdoor air temperature, weather status and building management information The following pages illustrate a sample automatic control system for air-conditioning and utilities, and a sample integrated BA system (3) Resource/energy saving Utilizing natural energy effectively and limiting unnecessary use of resources or energy, using the methods like controlling and maintaining a desired temperature setting accurately, or by employing only outdoor air necessary to carry out control in response to the load placed in the building Fundamentals of Automatic Control This section describes the mechanism of automatic control, important factors in air handling control including temperature, humidity, pressure, flow rate, response, methods and how to read the implementation diagrams as well as notes for designing automatic control systems Please note that to make the descriptions in this document simpler and easier to understand, some non-technical expressions may be used in the sections describing the theory of automatic control 2.1 General of Automatic Control changes in setting temperature or Necessary changes changes of of temperature disturbance, a delay occurs in the system until control action is (appearance) (appearance) Dead time Time constant taken and the Dead time & Time constant actual room temperature starts changing This is called dead time The time taken from start of changes in room temperature to re-establishment of set temperature is called the time constant The quality required for automatic control in such systems is quick response and stability Quick response means to achieve the target value as soon as possible Stability means to keep the system which achieved the target constant To design automatic control, function and quality must be determined in line with the characteristics of the applicable control and budget Temperature Figure shows an example of manual adjustment and Figure shows an example of automatic control As you can see in Figure 5, an automatic control system consists of a sensing element, a controller and a final control element The sensing element is an alternative to human vision, the controller which makes comparisons and judgments is an alternative to the brain and the final control element is a substitute for the hands and feet Automatic control systems always compare the actual temperature with the desired temperature and work to eliminate the difference between them To a control system, changes in outdoor air load such as outdoor air temperature or solar radiation and changes in room load such as number of occupants are added as disturbance If there is no change in internal or external conditions, once a valve (final control element) is set to the optimum position, the temperature is held constant However, loads fluctuate with changing external and internal conditions, making automatic control necessary As the figure on the right shows, when there are Room temperature 20°C Steam a)Manual adjustment of room temperature Desired value 25°C 20°C In manual adjustment you look at the current room temperature, compare it with the desired value, decide whether to open or close the valve and manually set the valve to change the flow rate of steam As the result, the supply air temperature and room temperature change and you visually confirm the result b) Flow (temperatures in the diagram are examples) Figure Temperature controller Manual adjustment Outdoor air temperature Infiltration, solar radiation Change in number of occupants Thermostat Control differential Motorized valve Steam + Comparison Set point (Temperature setting) a)Automatic control of room temperature 25°C Amount of control (room temperature) Issues signals to controller to reduce control differential Motorized valve AHU (Room) 20°C Starts operation at the signal from the controller and changes the temperature of the control target Detects room temperature 20°C b) Flow (temperatures in the diagram are examples) Figure 5 Automatic control Fundamentals of Automatic Control 2.2 Automatic Control Methodology There are various methods for operating the controller of automatic control equipment These are selected and adopted according to the Two-position (ON/OFF) control Item Proportional (P) Control Setting dial Setting dial Mechanism (electric control device) Increase in temperature Snap switch Differential Potentiometer Proportional band ・ The position of the target value varies depending on the controller Fully open Position Position Action diagram (heating) Diaphragm Diaphragm Increase in temperature Fully closed (Temperature) Amount of control (Temperature) Amount of control Target value Target value Amount of control Target value Differential Fluctuation in room temperature Amount of control Target value Response (response when the system is loaded in progressive stages.) ・ The position of the target value varies depending on the controller Offset Time Control element Disturbance Recommended control system Time Dead time Short Short to medium Time constant Medium to long Medium to long Size Small Small to medium Speed Low Low to medium Features Applications ・Select either of the two fixed amounts control signal ・The setting is just a target value It does not achieve the exact set point ・If the differential is too large, the fluctuation increases; if it is too small, it turns on and off repeatedly, an effect called 'hunting.' ・Relatively small and stable system ・Room temperature control, where it is OK if the temperature varies around the target value (differential) Proportional band Control characteristics of the control target, the required degree of control accuracy and the budget available This section describes a typical control response used in automatic control of air-conditioning ・The amount of operation is proportional to the current value of the action signal ・The setting is just a target value An offset (remaining differential) remains, since no action is made to achieve the exact set point ・If the proportional band is wide, the offset is large; if it is too small, hunting occurs ・Control target with minimum disturbance and lag ・Room temperature control, where a high degree of accuracy is not required Figure 6.1 Action of automatic control (1) Action diagram (heating) Off Decrease in amount of operation (Temperature) amount of control Proportional + Integral + Derivative (PID)Control (Temperature) Amount of control Dead band Set point Target value Control element Disturbance Time Proportional band Set point Dead band Position Dead time Short Short to medium Short to long Time constant Short Short to long Short to long Size Small to large Small to large Small to large Speed Low Low to medium Low to high Features Applications ・When an action signal exceeds a certain range(dead band),it increases/decreases the amount of operation at a certain speed ・The setting is just a target value It does not achieve the exact set point Proportional band Amount of control Time Time Recommended control system Set point Amount of control Amount of control Response (response when disturbance is added in the systems loaded in progressive stages.) Proportional band (Temperature) Amount of control Proportional band Diaphragm Increase in amount of operation Proportional + Integral (PI) Control Amount of operation Floating Control Set point Control Item Amount of operation Fundamentals of Automatic Control ・Adds a derivative function to the ・Adds the integral action to the proportional action to eliminate offset PI control Provides a faster response and keeps the control target at or very near the set point ・System where there are ・System with minimum lag and time ・Systems with large disturbance significant load changes and a constant ; disturbance can be large ・Room temperature control or high degree of accuracy is pressure control where supply air ・Tank level control, etc temperature control or high degree of required ・Special constant temperature and accuracy is required constant humidity control, pressure control, etc Notes:P: Proportional I : Integral D: Derivative Figure 6.2 Action of Automatic Control (2) Fundamentals of Automatic Control 2.3 Application for Automatic Control Device According to its principle and structure, the automatic control equipment for air handling is classified as follows: (See Figure on the next page) • • • • • Electric Electronic Pneumatic Electro-pneumatic Direct Digital Control (DDC) These methods are chosen for their specific characteristics (Figure 7, next page) With the recent digitalization of products, it is getting more difficult to categorize these methods simply according to their operating principle and structure Please note that in this document some devices are regarded as electronic due to how they are applied, even if they use built-in digital circuits The structure, operating principle and type of each device is explained in Section In Japan, compared with America and Europe, pneumatic/electro-pneumatic methods using pneumatic pressure as the input signal are found in only a few applications, such as chiller plant control or explosion-proof systems, where large valves are used, or hospitals, where many valves are used In electric control devices, mechanical elements such as diaphragms or nylon tapes are used and sensing elements and a controller are included in a single unit These devices are commonly used as they are convenient to handle and feature low cost However, it is expected that these devices will be replaced by electronic digitized products with a similar appearance Microprocessors are increasingly being mounted on electronic devices, but DDC is becoming even more widespread Further details on DDC are given in Section 3.3 Here, DDC is categorized as a product that obtains various function and benefits by communicating with main building management system In this regard, it is different from electronic devices with micro processors ... Automatic Control 2.1 2.2 2.3 2.4 2.5 2.6 General of Automatic Control Automatic Control Methodology Application fo Automatic Control device BMS & Automatic control. .. element and controller integral types are available ・Sensing element and controller are electronic control ・Final control element uses pneumatic control Attains advantages of both control ・Digital... locations consistent with the control items Determine locations of sensors Select the control method Design control logic Select the control devices Select the control valves Determine the types

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