Building Automation System Interfacing to a VAV System

Building Automation System Interfacing to a VAV System A BAS monitors inputs. . . Analog m Return air temperature m Off-coil temperature m Duct static pressure Binary m Filter clean/dirty status m Fan hand/off/auto status m Fan alarm m Fan status

Building Automation System Interfacing to a VAV System. . . and controls outputs Analog m Cooling coil valve position adjust m VSD setpoint adjust Binary m Return air dampers control m Fan start/stop control

Building Automation System CP VSD Points in Control Panel Fan Speed Control Trip Alarm A B B A Auto/Manual Status I O I O I I Fan Start/Stop Control

Building Automation System Return Air Temperature Uses a bulb-type sensor. Measures temperature of air returning from space through ceiling plenum. Typically 28°C to 30°C due to heat load and heat gain in plenum from lights. Indication of average space temperature

Building Automation System Return Air Damper Control Only used when VAV AHU is used for pressurization during fire mode. Normally, damper is full open to allow return air to mix with fresh air. In fire mode, damper shuts so AHU pressurizes space to assist smoke spill system and control movement of smoke

Building Automation System Filter Alarm Switch which closes when differential pressure across filter exceeds a certain value. As filter gets dirty, it clogs up and differential pressure increases. When the switch closes the operator is advised to replace the filter.

Building Automation System Cooling Coil Control Chilled water valve is controlled to maintain off-coil temperature setpoint. Actuator can take one of following signals: m Digital communication bus m 0 -10 VDC m 4 -20 m. A

Building Automation System Off Coil Temperature Uses averaging sensor to measures air temperature after cooling coil. Used to control cooling coil to achieve an off coil setpoint of 10°C to 14°C. Bulb type supply air temperature sensor sometimes used in place of off coil temperature.

Building Automation System Fan Speed Control Signal from BAS changes setpoint of Variable Speed Drive controller. Signal from BAS is either 0 -10 VDC or 4 -20 m. A Variable Speed Drive controller sends appropriate signals to fan.

Building Automation System Trip Alarm Voltage-free contact closes when fan motor trips due to: m Motor overload m VSD overload When trip alarm occurs, operator is alerted and advised to investigate.

Building Automation System Auto / Manual Switch If somebody has taken control away from the BAS by changing the Hand/Off/Auto switch away from Auto position, the operator is advised. If switch is Manual position, operator knows that he has no control over the fan.

Building Automation System Fan Start/Stop Control Applies 24 VAC signal to control panel. VSD manages timing associated with soft-start of fan.

Building Automation System Fan Status Uses differential pressure switch to give positive feedback of fan operation.

Building Automation System Static Pressure Controlled by pressure control loop to achieve a setpoint.

Building Automation System Hardware Elements

Building Automation System

Building Automation System DDC Controller n One AHU per controller for fault tolerance n Stand-alone DDC control program stored in E 2 PROM n Each analog input can also be configured to monitor two binary inputs n Default time schedule for stand-alone operation n No battery

Building Automation System N 2 Bus n Communication network between DDC controllers and Network Control Unit n 3 wires, RS-485, 1500 feet n Sends start/stop and adjust commands from NCU to DDC controllers n Reports all binary change of states to NCU n Reports analog values when requested by NCU

Building Automation System Network Control Unit n Provides BAS features for associated DDC controllers n Fault tolerance - no single point of failure n System performance independent of size n “PC in a box” n 80386 processor n Up to 10 Meg SIMM n 2 ISA slots

Building Automation System Network Control Unit n Connection points for: n Network Terminal n Notebook PC n Printer n Modem n 72 hour battery backup of programs and data n Real-time multi-tasking operating system

Building Automation System N 1 LAN n Communication between Network Control Units and Operator Workstations n Standard 2. 5 Mbaud ARCNET LAN n Coax or fibre, bus or star n Object oriented protocol n Johnson Controls will release protocol information at no charge

Building Automation System Operator Workstation n IBM Compatible PC n Microsoft Windows Graphical User Interface n Scanned photographs n Autocad floorplans n Schematics built from symbol libraries n Real-time field data superimposed on background graphics

Building Automation System Operator Workstation n Historical data from NCU is archived in d. Base files n NCU can archive data in multiple workstations concurrently so that data is not lost if PC fails n Other Windows programs can run concurrently n Other software can access BAS data using Dynamic Data Exchange (DDE)

Building Automation System Network Terminal n Hand held device for system access outside of control room n Can be connected to NCU or at remote connection n User friendly “finger mouse” operation n Access to all system data including historical data n Point names and password consistent with PC

Building Automation System Fire Panel Integration Chiller Panel Integration

Building Automation System Third Party Integration A number of vendors have released their communication protocol to Johnson Controls. Joint testing is done to ensure that the high level interface does not interfere with the properation of the third party system.

Building Automation System Software Features

Building Automation System Password n n Limit unauthorized access 5 levels of access Monitor n Monitor, Control, Modify, Program, Password n n n Same password used at PC and Network Terminal Encrypted database stored at each PC and each NCU

Building Automation System Network Map - JCTow er + Vent + Electri c - Air_Co n - Level_ 05 AHU_05 Level 5 Air Handling Unit VAV_05 Level 5 VAV Terminal Units + Level_ 04 + Level_ 03

Building Automation System Graphic Penetration Graphic Window

Building Automation System Point Focus n n All information about a point in one summary Line graph showing samples over past 24 hours for analog points Dynamic line graph which updates every 20 seconds for analog points Last 10 change-of-states (ON/OFF) with time/date for binary points

Building Automation System Point Focus Window Building System Point History 30. 0 10/10/ 94 07: 00 Current 16. 7 30. 0 10/10/ 94 12: 07: 15 12. 3

Building Automation System Alarm Message Point Focus Window Building System Point History 30. 0 10/10/ 94 07: 00 Current 16. 7 30. 0 10/10/ 94 12: 07: 15 12. 3 CRITICAL ALARM EVENT 10/10/94 12: 07: 17 BuildingSystemPoint 15. 0 Deg C Hi Alarm Temperature is outside of normal operating range - ensure valve is Look Now Look Discard View 10. 0 under control 10. 0 Later System

Building Automation System Alarm Message Alarm message routed to multiple PCs Alarm event detected at Alarm message routed NCU to remote location through modem

Building Automation System Report Router / Alarm Manager n n Distribution system for messages and files Manages alarm messages, Totalization files, Trend files and Point History files Concurrent updating of multiple locations for fault tolerance Feature executed by each Network Control Unit for fault tolerance

Building Automation System Archiving of Historical Files Copy of file archived in multiple PCs Historical in d. Base format file stored Copy of file sent in NCU to remote location through modem

Building Automation System Totalization n n Maintains records of run-time Allows scheduling of preventive maintenance based on usage Data archived in multiple PCs for fault tolerance Built-in graphing functions Data can be exported to other applications such as Maintenance Management software

Building Automation System Trend n n n Periodic sampling of selected points 12000 samples kept in each NCU Samples archived in multiple operator workstations for fault tolerance Built-in graphing functions Data available to third party software

Building Automation System Point History n n Continuous record of all points in the BAS System Allows proactive response to occupant complaints or alarms Data available at all Operator Workstations and Network Terminals Unique feature only available with Metasys

Building Automation System Trend Only Point History I will start collecting data I always have the now and hope that the same data required before problem happens again. I need it.

Building Automation System Scheduling n n n Automatic execution of commands or summaries based on a time schedule One time schedules to accommodate special situations Automatic updating of point status after a power failure Report generation by each NCU for fault tolerance Default schedules in each DDC for fault tolerance

Building Automation System Demand Limiting / Load Rolling n n n Advanced energy management algorithms Actions co-ordinated between features Prioritization of loads Built-in safety parameters Utility Profile to track electricity bills

Building Automation System Dial-Up I/O n n n Remote PC can access network Remote telephone can access network in tenant mode or operator mode Critical alarms directed to: n Remote printer n Remote telephone (voice synthesis) n Numeric pager n Text pager