Honeywell AUTOMATIC CONTROL SI Edition User Manual

MICROPROCESSOR-BASED/DDC FUNDAMENTALS
147ENGINEERING MANUAL OF AUTOMATIC CONTROL
If the DDC system is provided with a BMS having a color
monitor, a graphic may be required to be displayed with live,
displayable and commandable points (12 total). If a BMS is
not provided, the points may be required to be displayed on a
text terminal (fixed or portable) at the system level controller.
Step 3—Write a detailed sequence of operation for the process.
The hot water pump starts anytime the outside air temperature
drops to 11°C, subject to a software on-off-auto function.
When hot water pumping is proven by a current sensing relay,
converter controls are energized. Hot water temperature setpoint
varies linearly from 50°C to 77°C as the outside air temperature
varies from 16°C to -20°C. The converter steam valve is
modulated to maintain a converter leaving water temperature
according to a varying reset schedule.
The steam valve closes anytime hot water pumping is not
proven and anytime the valve actuator loses motive power.
Step 4—Develop the detailed flowchart.
Step 5— Write the program.
See the Air Handling System Control Applications section
and the Chiller, Boiler, and Distribution System Control
Applications section for other examples of Microprocessor-
Based/DDC systems.
Fig. 18. Flowchart Example.
M13120
NO
YES
TURN
PUMP
OFF
YES
O.A.
TEMP
EQUAL TO OR
BELOW
11°C
PUMP
ON?
START
PUMP
CLOSE
STEAM
VALVE
ENERGIZE
CONTROL
SYSTEM
CONTROL
SYSTEM
MAINTAINS
RESET
SCHEDULE
NO
CONTROL
SYSTEM
ENERGIZED
PUMP
ON?
YES
NO
YES
END
NO
START

Honeywell AUTOMATIC CONTROL SI Edition Specifications

General

Brand	Honeywell
Model	AUTOMATIC CONTROL SI Edition
Category	Control Systems
Language	English