HVAC, Heating Ventilation Air Conditioning BMS
- 1. BMS (HVAC)
- 2. Basic of Instrumentation • Us our Body and its parts • Our Body Reflexes
- 3. In BMS INPUTS:- Sensors Temperature(of room) Humidity (of room) Flow Rate (chilled Water) Pressure(of Fire Hydrant) Level (of a Tank) Run status (Pumps, Fans)
- 4. Temperature Sensors – Sensing technologies • Thermistor – Accurate over limited range – Point type only – Used for space temperature • Nickel Wire – General purpose sensor – Point or averaging type – Used for space or duct – Application Issues • Mount inside thermal well for water temperature • Mount return air sensor away from fresh air stream • Mount space temperature sensor : – At 1500 mm height – On inside wall – Away from direct sun or other heat sources • Platinum – High accuracy / linearity – Point type only – Precision applications • Ensure off-coil sensors are far enough away from coil • Outdoor air temperature sensors require sunscreen • Calibrate using precision resistor, validate using digital thermometer • Know mounting scope of responsibility
- 5. Pressure Sensors – Air Static Pressure • Used to control VFD based on VAV duct static • Must be mounted in region of laminar flow; five duct diameters from restrictions • Active sensor – Water Static Pressure • Used to monitor pressure at top of sprinkler riser • Commercial grade sensors can leak – Air Differential Pressure • Used to calculate airflow from velocity pressure – PVELOCITY = PTOTAL - PSTATIC – CFM = 4005 * AREA * (PVELOCITY / K FACTOR)½ • Used in VAV boxes and air flow monitoring stations – Water Differential Pressure • Used to control bypass valve or VFD • When controlling bypass, best to mount at last AHU • Do not try to save costs by using two static pressure sensors • Calculation error of same magnitude as signal may ocur.
- 6. Other Sensors Q Carbon monoxide Q Control car park ventilation fans Q Carbon Dioxide Q Used as indirect indicator of indoor air quality Q Waterflow Q Mount in region of laminar flow; five diameters from restrictions Q Many technologies: Q Annubar Q Paddlewheel Q Electromagnetic Q Turbine Q Humidity Q Used to measure the Relative Humidity in air. Q Some humidity sensors comes with in built temperature sensors also. Q Electrical Transducers Q Current Transducers Q Voltage Transducers Q Lux Level Sensors Q To measure the intensity of light.
- 7. In BMSOUTPUTS:- Control Valves VFD Speed Command Air DampersActuators ON-OFF Command (Fans, Pumps, Boilers)
- 8. INPUTS & OUTPUTS INPUTS e.g Analouge (varying-reading) AI Temperature, Humidity, Water Flow , Air Flow , Tank Level, Energy KW, Voltage, Current, Pressure, pH, Conductivity Digital (Binary-ON or OFF) DI or BI Status (on/off, airflow , run, open/close) Alarm Trip OUTPUTS e.g Analouge (varying-positioning) AO Fan Speed regulating (0 to 100%) Chilled water valvecontrol (0 to 100%) Digital (Binary-ON or OFF) DO or BO Command (on/off, open/close)
- 9. I/O Building management system relies on 4 types sensory information to make a control decision Analog inputs : are used to read a variable measurement. Examples are temperature, humidity and pressure sensor which could be thermistor, 4-20 mA, 0-10 volt or platinum resistance thermometer (resistance temperature detector), or wireless sensors. Digital input : indicates if a device is turned on or not. Some examples of a digital input would be , an air flow switch, or a volt-free relay contact. Analog output : controls the speed or position of a device, such as a variable frequency drive, a I-P (current to pneumatics) transducer, or a valve or damper actuator. An example is a chilled water valve opening up 25% to maintain a setpoint. Digital outputs : are used to open and close relays and switches. An example would be to turn on the parking lot lights when a photocell indicates it is dark outside. A typical Mid Size Building may have 800 -2000 sensory points also known and I/O points. A complex Building like an Airport may have more than 5000 points
- 10. DDC Controllers Q Types of DDC controllers Q Fixed function Q Configurable Q Text programmable Q Graphic programmable Q Point Definition Q Ranging (linear, calculated, Q Control Loops Q Proportional plus integral control commonly used polynomial) Q Filtering (smoothing and debounce) Q Interlocks Q Other software routines used in local control logic Q Minimum, maximum, average, calculator, etc. Q Psychometric calculations Q Timing (delays, pulses, etc.) Q Boolean and comparator operators Q Time clock and backup schedules
- 11. DDC Physical
- 12. Control System
- 13. Sl. No IO Description AI DI AO DO FIELD DEVICE 1 AHU On/Off 0 0 0 1 AHU panel to accept 2A NO contact 2 AHU Run Status 0 1 0 0 Differential Pressure Switch across blower 3 AHU Auto/Manual Status 0 1 0 0 Pot . free contact @ AHU Panel 4 AHU filter Status 0 1 0 0 Differential Pressure Switch across filter 5 Return air temperature 1 0 0 0 Duct type temperature sensor 6 2 Way chilled water modulating valve control 0 0 1 0 2 way Modulating Valve 7 Chilled water return header flow rate 1 0 0 0 Flow meter TOTAL 2 3 1 1
- 14. Basics of HVAC Pot with water Evaporation through the pores of Mud Pot makes the water inside cool Purpose of HVAC The main purpose of HVAC is to provide the people working inside the building with “CONDITIONED AIR” so that they will have a comfortable and safe work environment.
- 15. What is Conditioned Air?Conditioned Air” means that the air is clean and Odor-Free, and the temperature, humidity and movement of air are within certain comfort range. Comfort Zone: (ASHRAErecommendation) – – – – – – Temp : 22.7oC to 26.1oC Relative Humidity : 50% Air Velocity : 30 feet per minute
- 16. What is AHU? • AHU is Air Handling Unit Contains:–Fan, Cooling coil , Air Filter
- 22. Inputs to the Controller:
- 23. Outputs from the Controller:
- 24. What is a Chiller • A heat exchanger using air, refrigerant, water and evaporation to transfer heat (BTUs) to produce air conditioning (measured in tons). • A chiller is comprisedof an evaporator, compressor, condenser and expansion valvesystem.
- 25. Cycle
- 29. Chiller Plant
- 30. Chiller Plant with BMS sensor
- 32. Control Logic
- 33. Building Management System-: Begin with the basics • BMS – Building Management system Building Automation system •A BuildingManagement System (BMS) is a blend of hardware & software based control control system and installed monitor electrical in buildings to the building’s & other utilitymechanical, equipment
- 34. Building Services Services Equipments Mechanical system HVAC , Plumbing , Fire Fighting, STP Electrical System Electrical DB’s/Lighting control & monitoring, Generator set, UPS Utility Lifts, FireAlarm System, Security System,Public address system
- 35. What is a Building Automation System? Q A BMS system collects the operating information required for intelligent building management. Q It analyses the operation of the building systems by viewing all important temperatures, humidities and equipment status. Q Further to collection of these data, the BMS presents these data on the screen with full color • Automates some control strategies such as turning equipment On/Off according to a time schedule – ensures energy savings • Allows an operator sitting at the BMS work station to view key information about the building – improves building operations • Allows an operator sitting at the BMS work station to control some of the equipment in the building – improves building operations allowing remote control / over-ride where necessary • Maintains an audit trail of what happened and when it happened – improves building management by means reporting and traceability • Maintains historical data for selected information (like temperature, humidity ..etc) – improves building management by means reporting and traceability • Alerts the operator at the BMS work station when readings fall outside of normal range (i.e. breaker trips, temperature too warm, etc.) – improves building management by having a faster reaction time to problems • By doing the above and more a BMS system saves manpower, ensures productive occupants (especially in an office environment), prolongs equipment life, and the most important of all saves energy. diagrams (graphics) for the ease of understanding.
- 36. BMS Protocols BMS system manufacturerdivided predominantly into two different protocols,mentioned below- • BACnet - A Data CommunicationProtocol for BuildingAutomation and Control Networks developed by ASHRAE. It gives freedom to client to connect all BACnet compliant devices and ease in commissioning& configuring. • Lonworks -Lon Works is actually a family of products originally developed by the Echelon Corporation. At the core of this technology is a proprietary communications protocol called Lon Talk. Here one needs to buy license for each individual controllers & devices. Commissioning requires software key (dongle) all the time for commissioning& configuration. • Modbus is developed by Modicon in 1979. It is used to establish master- slave/client-server communication between intelligent devices. It is a de facto standard, truly open and the most widely used network protocol in the industrial environment and devices.
- 37. BMS System Architecture –• IP- 1 Tier Where all controllers areconnected to HMI on LAN.
- 38. RS 485 – 2Tier Level1-: where all controllers are connected to each other in daisy chain fashion & then after they connect to router orgateway. Level2-: When router or gateway is connected to any HMI for monitoring & controlling.
- 39. Building Automation System Software User Interface and Password Energy Operations Maintenance Operator Workstation (long term storage) Operator Workstation Where this feature resides ü ü ü Control Logic Demand Limiting and Duty Cycling Historical Data Graphics Scheduling Supervisory Controller DDC Controller Supervisory Controller Operator Workstation Supervisory Controller Supervisory Controller (processing) Operator Workstation (long term storage) ü ü ü ü ü ü ü ü ü ü ü
- 40. BMS Typical BOQ- It can be categorized in 3 broad categories- POT(Portable Operator1. BMS controllers, Softwares, Terminal),integration & PC. 2. Field Devices- It comprises different kind of sensors, switches, actuators, Transmitters etc 3. Cables & conduits
- 41. 1. BMS controllers, Software's, POT (Portable Operator Terminal), for integration & PC. • Controllers selection can be done based on the IO (Input Output) requirements directly just to match AI(Analog Input), AO(Analog Output), DI(Digital Input), DO(Digital Output) in the layman’s language. • Integration to collect the data from different devices.
- 42. 2. Field Devices- Comprises different kind of sensors, switches, actuators, Transmitters BMS Areas Categor y Type Sub- Category Application AHU(Airside) Temperature(cu m Humidity/RH) Sensor Room To know the actual Temp inside without cooling Duct To know flowing supply & Return Air air Temp(& RH) inside duct for Differential Pressur e Across AHU Fan to check it is on or off physically, Switch Air across filter to check the status Valve & Actuators Across cooling coil Chillers, cooling Temperature(cum To Know water temperature from the chillers & to the towers(Waterside) Humidity/RH) Sensor Immersion chillers Outside To Know outside temp & RH Differential Pressur e Switch Water Across Pumps to check it is on or off filter to check the status physically, across Others Level Transmitters Water To know the water level Oil To know the oil level CO2, CO sensor Room To know the air quality as in parking lot
- 43. 3. Cable It generally can be categorizedin two differentapplications-: • Signal/ControlCable:From differentfield devicesto controllers & from Controllers to field devices to controlthe equipments • CommunicationCable:cable between differentcontrollers,routers & gatewaysfor the purpose of intercommunication between controllers. • Integration cable:cable required for monitoring of third party devices.
- 44. Cable Selection BMS Areas Category CableType Application AHU Duct, Room Temp sensor 2c x 1 sqmm shielded PassiveTemp(2c) signals from sensor to controllers Temp cum humidity sensor 4c x 1sqmm shielded Passive Temperature(2c) & Active(2c-power) RH measurement from sensor to controllers DP Switch for Air 2c x 1 sqmm shielded Passive Temp(2c) signals from switch to controllers AHU FAN VFD 2c x 1 sqmm shielded Run status 2c x 1 sqmm shielded On/off status 2c x 1 sqmm shielded Relay output for VFD On/OFFOperation Valve & Actuator 5c x 1sqmm shielded Control & Power (3c power and command) & Monitor (2c)
- 45. Integration BMS Areas Category CableType Application Integartion DG 2c x 1.5 sqmm twisted pair shielded Integration is only to collect data from different devices to monitor & generate reports UPS 2c x 1.5 sqmm twisted pair shielded Integration is only to collect data from different devices to monitor & generate reports VAV's 2c x 1.5 sqmm twisted pair shielded Integration is only to collect data from different devices to monitor & generate reports Electrical Panels 2c x 1.5 sqmm twisted pair shielded Integration is only to collect data from different devices to monitor & generate reports Chillers 2c x 1.5 sqmm twisted pair shielded Integration is only to collect data from different devices to monitor & generate reports Security & Fire Alarm system 2c x 1.5 sqmm twisted pair shielded Integration is only to collect data from different devices to monitor & generate reports Elevator 2c x 1.5 sqmm twisted pair shielded Integration is only to collect data from different devices to monitor & generate reports
- 46. BMS Design Aspects Basic data required before you start system design: 1. Input / Output summary for all subsystems, which need to either monitor or control. 2. Selection of appropriate field devices. 3. All integration devices & respective point details which has to be monitored. 4. Signal & Communication cable route layout (at least tentative). 5. Panel (Enclosure for controllers) location, BMS PC location. Steps to follow for designing-: 1. Select the suitable controllers required for the requirement. 2. Select the enclosure to mount those controllers, which includes power supply for controllers & other wirings for field device connection. 3. Now start with the AHU designing which includes signal & control cabling requirement for different field device selection as per the requirement. 4. A typical AHU generally requires following field devices-Temperature cum Humidity sensor (or only Temp) in return & supply duct. Differential Pressure Switch (For Air) across the AHU Fan, Filter, Actuators for AHU Line. 5. A typical AHU will have following wiring connection- Connection to all Field devices, Connection to electrical panels as per I/O, connection to VFD’s. 6. A typical Chiller side will have following field devices-Immersion type temperature sensor (for supply & return pipes), Butterfly Valve & Actuator in each chiller supply, differential Pressure sensor across main supply & return . 7. A typical chiller will have connection to all field devices, chiller panels, Pump VFD’s.
- 47. BMS Commissioning Aspects – Air Side Commissioning- It comprises individual commissioning of AHU (Air handling Unit), CSU (Ceiling Suspended Unit), Fans & associated field devices. • We need to measure each field devices value during AHU commissioning as first task to make sure all field devices are working & then all points can be put in alogic. Water side commissioning – It comprises individual commissioning of Water cooled chillers, Air cooled chillers, Cooling towers, Primary pumps, Secondary pumps, VFD’s & associated field devices • We need to measure each field device value & other connected points value individually before putting them into logic. Integration of Air side & water side in a logic-This is to integrate all independent system in logic. Which can work automatically based on the user defined parameters without any conflict of individual system functionality.
- 48. BMS Commissioning Aspects Integration of monitoring points- • This is to collect all data in BMS system for the purpose of monitoring only. • PICS details i.e mapping details to be taken from respective equipment supplier. • Protocol significance for integration purpose-whenever we say one device supports Modbus over RS485, here RS 485 signifies physical channel (cable type) & communication port while Modbus signifies data pattern. Therefore all devices in a loop must support same protocol & configure to the same. • Cable used for integration is 2 core x 1.5 sqmm shielded • All monitored devices have to be looped in daisy chain connection to RS-485 port. Devices can support different communication over different protocols. We need to make sure whenever making a loop all devices should support same communication & protocol type. for instance Modbus over RS485. Client User interface (UI) • Client can change parameters as temperature & humidity from UI as per the comfort level & all basic information can be viewed on the UI.
- 50. SCHEMATICS-AHU
- 51. SCHEMATICS-TFA
- 53. Water Tank
- 54. EXHAUST FAN
- 55. CHILLER
- 56. CHW & CDW PUMPS
- 57. COOLING TOWER