10/11
Building Technologies Division CC1N7454en
20.11.2017
Diagram of switching mechanism
t1 t3
t6
t7
t4 t5
t8
t10
TSA
t9
t20
ABC
D
a
b
a
b
a
b
a
b
a
b
a
b
XV
XIV
XIII
XII
XI
X
IX
VIII
VII
VI
V
IV
III
II
I
7454d01/0204
a
b
19
16
910
20
11
8
18
15
23
24
12
7
7
12
a
b
a
b
a
b
a
a
a
a
b
Legend
AL Remote lockout indication Alarm Output signals of burner control
AS Unit fuse Required input signals
AR Main relay with contacts «ar...» Working relay
BR Lockout relay with contacts «br...» A Start command given by the control thermostat
BVx Fuel valve A-B Startup sequence
d1/d2 Contactor or relay B Operating position of burner
EKx Reset button B-C Burner operation
IONx Ionization probe C Controlled shutdown by control thermostat or pressurestat (R)
FR Flame relay with contacts «fr...» C-D Sequence mechanism runs to the end position after a
GP Gas pressure switch controlled shutdown by control thermostat or pressurestat (R)
H Main isolator D End position of burner Corresponding to the start position
L1 Lockout warning lamp
LK Air damper
Switching times in seconds
LP Air pressure switch
LR Load controller TSA Ignition safety time 4 s
M1/M2 Fan or burner motor t1 Waiting time or prepurge time 14 s
NTC NTC resistor t3 Preignition time 2 s
R Control thermostat or pressurestat t4 Interval fuel valve (BV1-BV2) 8 s
SA Air damper actuator t5 Interval between release of the 2
nd
fuel valve and the load
a: Changeover limit switch for actuator’s OPEN position controller (if present) 10 s
z: Changeover limit switch for actuator’s CLOSED position t6 Postpurge time 10 s
SB Safety limit thermostat t7 Interval until voltage at terminal 7 is present 2 s
Si External primary fuse t8 Duration of startup program 36 s
SM Synchronous motor of sequence mechanism t9 2
nd
safety time for 2
nd
stage 8 s
V Flame signal amplifier t10 Interval until air pressure check is started 6 s
(1) Input for forced energizing of the flame relay during the t20 Steps of switching mechanism with no change in the 26 s
functional test of the flame supervision circuit program Idle steps
(contact «XIV») and during safety time (TSA) (contact
«IV»)
W Limit thermostat or pressure switch
Z Ignition transformer
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