Riello 20155654, Installation, Use And Maintenance Instructions

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20155699 52 GB
Options
8.1.5 set-point changeover
You can switch set-point via input at terminal 5. When you use a
version with fixed set-point value you are able to select through
this contact one of two values listed in parameters P0048 and
P0050 with this contact.
While control by atmospheric conditions is activated additionally
you are able to select between two pairs of limit values (see con-
trol by atmospheric conditions and limit ranges).
Parameters for set-point 1 (for set-point switching) and set-point
min 1 (for control by atmospheric conditions) are the same. Sim-
ilarly, parameters set-point 2 and set-point min 2.
The corresponding content is assigned accordingly to selected
configuration.
While “control by atmospheric conditions” is activated and pa-
rameters are set correspondingly you may also implement an ex-
ternal set-point default.
This means set-point values can be adjusted via potentiometer
(or switched through resistors) manually or automatically. By
connecting a change-over switch, you can implement a night-
time reduction instead of “control by atmospheric conditions”.
A “control by atmospheric conditions” in combination with night-
time reduction is also possible. In order to achieve this combine
the control by atmospheric conditions with set-point switch over.
8.1.6 Start-up sequence
The firing rate controller has a start-up cycle (Fig. 92) in order to
slow down burners’ firing rate while starting.
The start-up cycle is passed during each new burner start. The
internal firing rate is held at user-adjusted value (P 0044) as long
as the boiler is cold. The actual value is below parameter set limit
(P 0043).
If controllers’ actual value is larger/equal to the parameter set
start-up maximum temperature, this startup cycle is cancelled.
In order to prevent that too large power demand of the plant hav-
ing the consequence that boil-er temperature for ending start-up
cycle is not reached, in parallel a startup timer is also trig-gered
in parallel (timer adjustable by operator, P0045).
As internal firing rate reaches parameter set start-up firing rate,
output is increased linearly step-by-step up to maximum firing
rate.
The rise of this linear increase is calculated from parameter set
start-up time.
Key (Fig. 92)
*(1) = P 0044
*(2) = P 0045
Fig. 92
S9616
Specified firing rate
Max firing rate / or highest
programmed point
Specified firing rate
parameterised start up
firing rate * (1)
Base firing rate ignition
Countdown until internal
firing rate reaches the
specified firing rate
Sp
ecif
ied
firin
g r
ate
Parameterised start up time *(2)
Time
Normal operation
Ignition
procedure