Rotex Controller Series, Product Documentation

Page: 159 / 192

EbV Product documentation THETA NORM/UNIT
10-7
Function: The set switch-over power in the CASCADE level and the basic load excess in the
HEAT GENER. level are only suitable for operation with a boiler control. Until the last
burner stage has been started (basic load mode), all active burner stages up to that
moment are reduced to the set switch-over power (ventilator rpm limitation).
Only the stage that was activated last operates according to the current requirement
value.
If a flow sensor is installed, the setpoint of the stage that was activated last is
calculated using a PI-algorithm.
If all stages are activated (full load mode), the capacity limitation is lifted and all
condensing boilers are enabled 100%. Then, all stages operate according to the
current setpoint.
If a flow sensor is installed, the setpoint is calculated using the PI-algorithm.
The stages operating at basic load mode are also monitored concerning the required
value. This may not become smaller than the required value.
If the capacity is reduced by one stage and the last stage is removed from the control
network, then the basic load mode is activated. Then the set basic load excess and
the capacity limitation of the stages operating at the basic load level are activated.
10.3.6 Operation with group reversal
High-end condensing technology is used especially in plants of large and middle
capacities when high efficiency is required (municipal plants), to cover a basic load
of an average annual capacity. The peak load is covered by conventional low
temperature boilers in the cold months.
In this technique, an activated stage reversal only affects the basic load heat
generators, not the peak load heat generators.
The first peak load boiler is switched on after all basic load heat generators are
activated and operating at 100 %, at full load.