17
T
W
T
N
T
S
T
VK
T
VK
T
VZ
T
NZ
5.5 Sequence of operations and wiring diagrams
Sequence of operations diagram
Boiler control
Burner motor
Ignition unit
Flame signal
Partial load
valve
Full load valve
Anti siphon
valve
Ratings
controller
Servomotor
ST2
MV2
ST1
ST0
Pre-purge/pre-
ignition
Boiler control
ON
Air damper on
partial load
setting
Open partial load
solenoid valve
Partial load
operation
End of waiting
time
Full load
solenoid valve
OPEN
Demand partial
load
Full load solenoid
valve CLOSED
Demand full load
Full load
solenoid valve
OPEN
Post purge
Switch times
Start waiting time (test) T
W
3·5 secs.
Pre-ignition time T
VZ
10 secs.
Post ignition time T
NZ
4 secs.
Safety time T
S
5 secs.
Waiting time partial load T
VK
5 secs.
Post purge time T
N
2·5 secs.
Servomotor run time in operation
full scale movement 0° to 90°
approx. 3 secs.