26
5
Firing Rate Controller (optional)
5.1.5
Start-up Sequence
The firing rate controller has a startup circuit, in order to slow down the burner's start firing rate.
The startup circuit is run during each new burner start. The internal firing rate is held at a value
P 792 adjustable by the user, for as long as the boiler is cold (actual value is below a user-
adjustable limit, P 791). If the controller’s actual value is equal to or larger than the parame-
terised startup maximum temperature, this startup circuit is cancelled.
In order to prevent a situation where an excessively large demand on system output, the boiler
temperature necessary to cancel the startup circuit is not reached, a startup timer is also trig-
gered in parallel (this timer can also be adjusted by the operator, P 793). Once the internal
firing rate reaches the parameterised startup firing rate, the output is increased linearly step-
wise up to the maximum firing rate. The slope of this linear increase is calculated from the pa-
rameterised startup time.
Fig. 5-2 Startup sequence
*(1) = P 792
*(2) = P 793
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