27/69
Siemens Building Technologies
Electronic Air / Fuel Ratio Control System
CC1P7873.1en
HVAC Products
6 Sequence of functions
15.10.2002
6
Sequence of functions
6.1 RVW25... and RVW26... with the burner control
The startup and shutdown sequence of the burner is determined by its burner control.
For safety reasons, the RVW26… demands a defined sequence that is matched to our
burner controls.
For this reason, certain output signals of the burner control are fed to the RVW26…
The functional sequence of startup and shutdown is monitored by the RVW26… and
must be in accordance with the sequence diagram.
With other actions (e.g. opening the control loop during the burner startup sequence or
lockout of burner control), other events can trigger the change from one phase to an-
other.
6.2 Explanations relating to the sequence diagram
The program sequence of the RVW26… is divided into a number of
phases
.
The sequence diagram shows the normal sequence of burner startup, operation and
shutdown.
A certain event is always required for a phase to change to the next (e.g. an input sig-
nal, a specific position of an actuator, etc.).
The events required by a phase to change are identified by a circle in the following dia-
gram.
Phase numbers 0…9 appear on the display.
During running phase «R», the display shows the burner's current output.
·
Phase «0» is the waiting phase (standby). During this period of time, there is
no
signal to demand burner startup
·
Phases 1…7 belong to the burner's startup sequence
·
Phases 8 and 9 belong to the burner's shutdown sequence (and after power ON)
These phase numbers also appear on the display of the handheld terminal AZW20.20.
