HOW DDC WORKS
CENTRAL WORKSTATION (control, monitor, manage)
-
talks to global controllers/building
controllers
-
send, receive, process, store,
print the data
-
check component and system status
-
check trends and monitor
performance of equipment
-
change set points, schedules
and settings
-
ASCENT COMPASS - Alerton
GLOBAL CONTROLLERS (integrate devices)
-
talks to field
controllers/zone controllers
-
connects/provides gateway to
allow communication
with devices made by different manufacturers
-
integrates different devices
-
ACM, BCM, VLX - Alerton
FIELD CONTROLLERS (control terminal units)
-
operates actuators, fans,
blowers, pumps
-
field controller for VAV, AHU,
Fan coil unit, chiller
cooling tower, boiler, terminal unit
-
VLC, VAV - Alerton
SENSORS
-
provide input, send signal to
controllers
-
display room setpoints and fan
status
-
display room temperature, outside
air temperature, relative humidity
-
MICROSET - Alerton
Receive Input
Information From Sensors
Process Input
Information
Respond with an Output
Action
Receive Feedback when
set point is met
Respond with another
Output Action
Example: How
a Furnace DDC works?
1.
Thermostat (Sensor) calls for
heat
2.
Thermostat switch is closed, sends
voltage signal to control board
3.
Control board (“Brain”)
receives and processes input signal from thermostat
4.
Control board closes contactor,
inducer fan motor starts
5.
Air flow switch/Sail switch
closes to confirm air flow supplied by fan
6.
Control board will activate
the Spark Igniter
7.
Control board activates Gas
Valve
8.
Burner ignites
9.
Flame Sensor detects flame
10.
Spark Igniter deactivates
11.
Control board energizes Indoor Fan Blower
motor
12.
Furnace supplies heat to the structure (room, home,
building, etc.)
13.
Thermostat temperature set point is met
14.
Thermostat opens switch, sends feedback signal
voltage to control board
15.
Control board shuts off the
Gas Valve and Induced draft fan
HOW BUILDING AUTOMATION SYSTEM (BAS) WORKS
BAS uses an integrated network of Workstations,
Global Controllers, Field Controllers, Sensors, Gateways, Routers, Repeaters,
Cables and other associated components that are designed and programmed to provide
the following building services:
- Networking
- Control, Monitoring and Alarms
- Data collection
- HVAC – Heating, Ventilation, Air-Conditioning
- Real-time Adjustments of Setpoints, Percent valve openings, etc
- Scheduling, Remote Operation and Remote Access
- Changing Modes, e.g. Economizer mode (to save on energy costs)
- Load and Demand Control
- Fire Protection
- Security
- Lighting management
- Energy Management
