FCU 500, FCU 505 · Edition 02.17
144
Legend
20 Legend
Ready for operation
Safety interlocks (limits)
HT
High temperature operation
Safety limits (limits during start-up = LDS),
control element position check
Gas valve
Air valve
Air/gas ratio control valve
Burner
P
Purge
A
External air valve control
Controlled air flow
Operating signal
Fault signal
FCU start-up signal
Emergency stop
PZL
Pressure switch for tightness control (TC)
PZL
Pressure switch for maximum pressure
PZL
Pressure switch for minimum pressure
PZL
Differential pressure switch
P xx
Input signal depending on parameter xx
M
Control element with butterfly valve
TC
Tightness control
p
u
/2
Half of the inlet pressure
p
u
/4
A quarter of the inlet pressure
3p
u
/4
Three-quarters of the inlet pressure
p
u
Inlet pressure
p
d
Outlet pressure
V
p
Test volume
GZL
Valve with proof of closure switch
Fan
Three-point step switch
Input/Output, safety circuit
I
N
Current consumption of sensor/contactor
t
SB
Safety time during operation
t
MP
Minimum pause time
t
L
Tightness control opening time
t
M
Measurement time during tightness test
t
P
Tightness control test period (= 2 x t
L
+ 2 x t
M
)
t
PN
Post-purge time
t
GV
Fan run-up time
t
E
Switch-on delay
t
PV
Pre-purge time
t
RF
Controller enable signal delay time