• A weight factor of 1 means that the real input value is used in calculations.
• A weight factor of 3 means that the input value is considered three times as big in calculations.
6. Bottom drop-down
• On: This input will be evaluated.
• Off: This input will not be evaluated.
7.2.2 Dynamic input selection
Each GP PID holds the possibility of up to three active inputs. All activated inputs are evaluated constantly, and the input causing the
greatest or smallest output is selected. Priority of great or small output is selected in the output settings.
Example explaining dynamic input selection
Ventilation of a container fitted with a genset inside is a realistic example for use of the dynamic input selection. The following three
variables depend on the ventilation, hence it makes sense to let them share the output.
• The container is fitted with a temperature sensor for internal container temperature. Due to lifetime of electronics inside the
container, maximum maintained temperature is desired to be 30 °C. (Input 1).
• The engine air intake is located inside the container, hence turbo compressor inlet temperature depends on the air temperature
in the container. Maximum maintained intake air temperature is 32 °C. (Input 2).
• The alternator is cooled by air in the container, hence the alternator winding temperature depends on the air temperature in the
container. Maximum maintained winding temperature is 130 °C. (Input 3).
This is the data that is used to configure the inputs in the screenshot in the previous paragraph (Inputs). All inputs are configured
with both full range of measurement (0 to 100 %) and a weight factor of 1. The common output to the ventilator speed drive is
configured to prioritise maximum output as explained in the next chapter, “Output”. This configuration is meant to ensure that none
of the input set points are continuously exceeded, unless maximum ventilation is reached.
A scenario of operation could be that the controller has been using input 1, and a temperature of 30 °C is maintained in the
container. At a point, the air filter housing is heated by radiation from the engine, causing input 2 to rise more above 32 °C than input
1 is above 30 °C. This means that input 2 now has the greatest positive deviation. All inputs are configured with a weight factor of 1
and maximum output is prioritised, hence the greatest positive deviation results in maximum output, or, to put it in another way, input
2 is now the one selected.
The genset is running at full load with a maximum of reactive load, and the alternator windings heat up beyond the 130 °C set point
due to high currents. At some point, input 3 will result in maximum output and hence be selected as the input used in output
calculation. Ventilation is increased and the winding temperature may reach a steady state of 130 °C with a container room
temperature of 27 °C and a compressor inlet temperature of 30 °C. As long as this is the situation, input 3 will remain the selected
input, as this is the input causing the greatest output.
In case of high ambient temperatures, the ventilation might not be able to influence the temperature enough, and the temperatures
start to rise above set point. The output will stay at 100 % as long as any of the inputs are continuously above their set points.
Weight factor applies to dynamic input selection as well. In the event that different weight factors have been configured for any of the
three inputs, maximum deviation cannot be equated to maximum output. If two inputs with similar deviation to their respective set
points are configured with weight factors of 1 and 2 respectively, the latter will result in twice the output as the first.
DESIGNER'S HANDBOOK 4189341275A EN Page 185 of 196
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