DDC Sequencing and Redundancy
Presenter
Sequencing Importance of sequencing Essen%al piece to designing and delivering a successful project Defines how disparate components interact to make up a system The fundamentals to sequencing Mechanical designers intent How it should operate How to control to meet both Simplicity is key Clear, concise and complete Overview of process Analyze mechanical design Outline SOO Fill in details Op%mize system
Sequencing Systema@c approach to developing SOO s. Map out en%re system, compartmentalize components if possible, analyze system on a component level Define instrumenta%on on a component level Develop I/O list for components including hardwired points and data connec%ons Define Instrumenta%on on the system level Develop I/O list for system Iden%fy set points, alarms, schedules and trends
Example System Chilled Water Plant Series water- side economizer Primary- secondary chilled water pumping Variable speed condenser water pumping Dual piping loops
Sequencing Systema%c approach to developing SOO s. Map out en@re system, compartmentalize components if possible, analyze system on a component level Define instrumenta%on on a component level Develop I/O list for components including hardwired points and data connec%ons Define Instrumenta%on on the system level Develop I/O list for system Iden%fy set points, alarms, schedules and trends
Map Out En@re System Define system by it s disparate components N+1 component redundancy One- to- one rela%onships
Compartmentalized Components Compartmentalize system as best as possible. Create Line- ups of equipment
Chiller Plant System Component Level Break down system to the individual component level
Sequencing Systema%c approach to developing SOO s. Map out en%re system, compartmentalize components if possible, analyze system on a component level Define instrumenta@on on a component level Develop I/O list for components including hardwired points and data connec%ons Define Instrumenta%on on the system level Develop I/O list for system Iden%fy set points, alarms, schedules and trends
Component Level Defining Instrumenta@on As laid out by the mechanical designer What instrumenta%on is required to meet intent and opera%on? Enable/Disable
Component Level Defining Instrumenta@on Unit Mounted Controller What instrumenta%on is required to meet intent and opera%on? Enable/Disable
Component Level Defining Instrumenta@on Unit Mounted Controller Shut- off/isola%on Valves What instrumenta%on is required to meet intent and opera%on? Enable/Disable
Component Level Defining Instrumenta@on Unit Mounted Controller Shut- off/isola%on Valves What instrumenta%on is required to meet intent and opera%on? Enable/Disable Capacity Control
Component Level Defining Instrumenta@on Unit Mounted Controller Shut- off/isola%on Valves Temperature Sensor What instrumenta%on is required to meet intent and opera%on? Enable/Disable Capacity Control
Component Level Defining Instrumenta@on Unit Mounted Controller Shut- off/isola%on Valves Temperature Sensor What instrumenta%on is required to meet intent and opera%on? Enable/Disable Capacity Control Opera%ng Restraints
Component Level Defining Instrumenta@on Unit Mounted Controller Shut- off/isola%on Valves Temperature Sensor Head Pressure Control What instrumenta%on is required to meet intent and opera%on? Enable/Disable Capacity Control Opera%ng Restraints
Component Level Defining Instrumenta@on Unit Mounted Controller Shut- off/isola%on Valves Temperature Sensor Head Pressure Control What instrumenta%on is required to meet intent and opera%on? Enable/Disable Capacity Control Opera%ng Restraints Op%miza%on
Component Level Defining Instrumenta@on Unit Mounted Controller Shut- off/isola%on Valves Temperature Sensor Head Pressure Control Addi%onal Sensors What instrumenta%on is required to meet intent and opera%on? Enable/Disable Capacity Control Opera%ng Restraints Op%miza%on
Sequencing Systema%c approach to developing SOO s. Map out en%re system, compartmentalize components if possible, analyze system on a component level Define instrumenta%on on a component level Develop I/O list for components including hardwired points and data connec@ons Define Instrumenta%on on the system level Develop I/O list for system Iden%fy set points, alarms, schedules and trends
Develop I/O List for Components
Develop I/O List for Components
Repeat instrumenta@on and I/O for other components Cooling Tower Condenser Water Pump Primary Chilled Water Pump Secondary Chilled Water Pump
Sequencing Systema%c approach to developing SOO s. Map out en%re system, compartmentalize components if possible, analyze system on a component level Define instrumenta%on on a component level Develop I/O list for components including hardwired points and data connec%ons Define Instrumenta@on on the system level Develop I/O list for system Iden%fy set points, alarms, schedules and trends
System Level Defining Instrumenta@on How do the disparate components interact with the system?
System Level Defining Instrumenta@on System Valves
System Level Defining Instrumenta@on System Valves Flow Meters
System Level Defining Instrumenta@on System Valves Flow Meters System Temp Sensors
System Level Defining Instrumenta@on System Valves Flow Meters System Temp Sensors Differen%al Pressure Sensors
Sequencing Systema%c approach to developing SOO s. Map out en%re system, compartmentalize components if possible, analyze system on a component level Define instrumenta%on on a component level Develop I/O list for components including hardwired points and data connec%ons Define instrumenta%on on the system level Develop I/O list for system Iden%fy set points, alarms, schedules and trends
Develop I/O List for System
Sequencing Systema%c approach to developing SOO s. Map out en%re system, compartmentalize components if possible, analyze system on a component level Define instrumenta%on on a component level Develop I/O list for components including hardwired points and data connec%ons Define instrumenta%on on the system level Develop I/O list for system Iden@fy set points, alarms, schedules and trends
Iden@fy Set Points, schedules, alarms, trends Avoid exact set points, baselines are recommended Typically done by Cx agent along with the balancing contractor Define schedules Alarms can be addressed as virtual points in points list as well as safe%es that typically take the form of hardware Define trends
Sequencing Understand the importance of sequencing Become in%mate with the fundamentals of the design Define your systema%c approach to developing sequences Keep it simple!
Ques@ons?
Redundancy in DDC Where and why redundancy in DDC is required Redundant systems within a facility DDC System Redundancies Redundant Instrumenta%on Redundancy in system architecture Physical separa%on of installed control components Dual power supplies with separate feeds to each control panel Network Redundancy Separate supervisory networks Redundant Servers PLC Systems
Redundancy in DDC Where: Mission Cri%cal Facili%es (MCF) What it means to be a Mission Cri%cal Facili%es that require 100% up%me 24 hours a day 7 days a week for normal business opera%on Redundancy provides maximum reliability but also generates maximum cost and complexity Examples: Data Centers, Hospitals, Laboratories
Redundancy in DDC Why: Enables con%nuous opera%on during cri%cal system failures Meets owner s requirements for minimized down%me Designing for redundancy in all building systems, including the DDC system may be required Site- wide control coordina%on Example coordina%on types: Temperature Control, Power restart, Load Shedding, Humidity Control, Pressuriza%on
Redundant Systems
Redundant Systems N+1 component redundancy Dual piping loops
Redundant Systems DDC system redundancy isn t addressed by Up%me Redundant mechanical equipment s%ll needs DDC to func%on properly Fault Tolerant Control Systems any single controller or communica%on network Redundancy in DDC is necessary to ensure any malfunc%on or loss of power within the control system will not affect cri%cal equipment opera%on
DDC System Redundancies Redundant Instrumenta@on Redundancy in system architecture Physical separa%on of installed control components Dual power supplies with separate feeds to each control panel Network Redundancy Separate supervisory networks Redundant Servers
Redundant Instrumenta@on System Valves Flow Meters System Temp Sensors Differen%al Pressure Sensors
DDC System Redundancies Redundant Instrumenta%on Redundancy in system architecture Physical separa%on of installed control components Dual power supplies with separate feeds to each control panel Network Redundancy Separate supervisory networks Redundant Servers
Redundancy in System Architecture DDC system architecture depends on the make- up of the mechanical and electrical systems DDC system architecture designs to achieve redundancy: Primary- Redundant Managers (True Primary/Redundant) Distributed Control (Line- Up Configura%on) Hybrid (Line- Up Configura%on with PR Managers) How to find the right design for your applica%on Compartmentalize the systems as best as possible
Redundancy in System Architecture Primary- Redundant Managers (True Primary/Redundant)
Redundancy in System Architecture Distributed Control (Line- Up Configura%on)
Redundancy in System Architecture Hybrid (Line- Up Configura%on with PR Managers)
DDC System Redundancies Redundant Instrumenta%on Redundancy in system architecture Physical separa@on of installed control components Dual power supplies with separate feeds to each control panel Network Redundancy Separate supervisory networks Redundant Servers
Physical Separa@on of Components DDC Controllers Variable Frequency Drives Redundant Sensors Control Valves Wiring
DDC System Redundancies Redundant Instrumenta%on Redundancy in system architecture Physical separa%on of installed control components Power redundancy Network Redundancy Separate supervisory networks Redundant Servers
Power Redundancy Control panels need to be powered at all %mes to properly func%on Examples: UPS power from two sources with a local ATS UPS power from electrical system with back- up generator and local UPS
DDC System Redundancies Redundant Instrumenta%on Redundancy in system architecture Physical separa%on of installed control components Dual power supplies with separate feeds to each control panel Network Redundancy Separate supervisory networks Redundant Servers
Network Redundancy Concept of self- healing communica%on busses Redundant topologies (network s virtual shape or structure) Ethernet Topologies Bus Topology Classic Star Topology Tree Topology (combina%on of bus and star) Ring Topology Redundancy through ring topology is becoming the most popular for the BMS market Wireless Mesh
Network Redundancy Bus Topology Uses a common backbone to connect all devices. Failure of one node or link affects the rest of network Works best with a limited number of devices due to the broadcast traffic it generates
Network Redundancy Star Topology Most common network setup If the central hub fails, all devices connected to that hub would be disconnected Performance of the network is dependent on the capacity of central hub (router or switch)
Network Redundancy Tree Topology Integrates mul%ple star topologies together onto a bus. This hybrid approach supports future expandability of the network much beier than a bus
Network Redundancy Ring Topology N+1 U%lizing industrial switches Redundant rings is becoming the most popular for the BMS market Ethernet rings will cause broadcast storms and can ul%mately cause the network to stop working How to fix this? - Spanning Tree Protocol
Network Redundancy Spanning Tree Protocol (STP) Although two cable paths exist, messages can only travel in one direc%on STP solves problems in a ring topology including broadcast storms STP does for an Ethernet network what a router does for an IP network Typically provides network recovery %mes of 30-60 seconds Rapid Spanning Tree Protocol (RSTP) Provides faster spanning tree convergence aler a topology change
Network Redundancy Wireless Mesh Topology Can take any of several possible paths from source to des%na%on. Devices are connected with many redundant interconnec%ons between network nodes In a true mesh topology every node has a connec%on to every other node in the network.
Network Redundancy The most common problems in any fieldbus or high speed digital communica%ons system are: Cabling and wiring faults: Reflec%ons, interference, cable rou%ng and grounding faults etc. Poor design and installa%on: Lack of awareness of avoidable issues at design stage, poor rou%ng, layout, untrained installers, inaccurate or insufficient system documenta%on Device and wiring failures: Rare but can lead to communica%ons faults or peripheral faults
DDC System Redundancies Redundant Instrumenta%on Redundancy in system architecture Physical separa%on of installed control components Dual power supplies with separate feeds to each control panel Network Redundancy Separate supervisory networks Redundant Servers
Separate Supervisory Networks SNMP monitoring on equipment back to a separate owner network and server Other secondary monitoring methods such as web based services
DDC System Redundancies Redundant Instrumenta%on Redundancy in system architecture Physical separa%on of installed control components Dual power supplies with separate feeds to each control panel Network Redundancy Separate supervisory networks Redundant Servers
Redundant Servers Servers are also at risk for being a single point of failure Server redundancy minimizes down%me caused by: Planned Maintenance Hardware Failure Redundancy Methods Two separate servers passive synchroniza%on rou%ne Two separate servers with an ac%ve synchroniza%on rou%ne Clustering and/or VM s (Virtual Machines)
Redundant Servers Two separate servers would have some manual back up and a passive synchroniza%on rou%ne Two separate servers with an ac%ve synchroniza%on rou%ne Two computers using separate network between them that buffers and replicates the data going into one machine Poten%ally lose the buffer as data is being passed between the two.
Redundant Servers Clustering and/or VM s (Virtual Machines) Two different things but from controls perspec%ve doesn t maier Server Clustering combining two or more servers that are interconnected to appear as one Load balanced clustering/fail over clustering Need clustering solware that monitors the ac%ve nodes in a server cluster and transi%ons a failed server s workload to the secondary node Virtual Machines maintain an exact mirror copy on a second physical server
PLC Systems PLC systems are more robust, have higher performance, faster networks and more flexible programming capability PLC s have the capability to have Hot Standby Processors (no PID tuning required): the scans of the primary and standby controllers are synchronized Redundant Power Supplies separate power supplies can be provided for PLC controllers. Redundant Networks Difference in costs between PLC and DDC control - up to 5:1 cost
Redundancy in DDC Where and why redundancy in DDC is required Redundant systems within a facility DDC System Redundancies Redundant Instrumenta%on Redundancy in system architecture Physical separa%on of installed control components Dual power supplies with separate feeds to each control panel Network Redundancy Separate supervisory networks Redundant Servers PLC Systems
Ques@ons?