DAB AD 2.2 AC Instruction For Installation And Maintenance page 98

4.5.1 Assigning the start-up order
Each time the system is activated, each inverter is associated a starting order. This setting establishes the order of inverter start-up.
The starting order is modified during use according to requirements, by the two following algorithms:
Reaching of maximum operating time
•
Reaching of maximum inactivity time
•
4.5.1.1 Maximum operating time
According to parameter ET (maximum operating time), each inverter has an hour counter, and the starting order is updated on the
basis of these values according to the following algorithm:
- if at least half of the value ET is exceeded, priority is changed on the first shutdown of the inverter (switch to standby).
- if the value ET is reached without stopping, the inverter stops unconditionally and this sets to the minimum restart priority
(switch during operation).
If parameter ET (maximum working time) is set to 0, exchange occurs on each restart.
See ET: Tempo di scambio par 6.6.9.
4.5.1.2 Reaching of maximum inactivity time
The multi inverter system has an anti-stagnant algorithm that is aimed at maintaining pump efficiency and integrity of the pumped
liquid. It acts by enabling rotation of the pump starting order to ensure a delivery to all pumps of at least one minute of flow every 23
hours. This is implemented regardless of the inverter configuration (enabled or reserve). Priority switch envisages that the inverter
stationary for 23 hours is set to maximum priority in the starting order. This means that it is the first to be started up as soon as flow
delivery is required. The inverters configured as reserve have priority over the others. The algorithm terminates action when the inverter
has delivered at least one minute of flow.
After the anti-stagnant interval, if the inverter is configured as reserve, it is set to minimum priority to avoid premature wear.
4.5.2 Reserves and number of inverters involved in pumping
The multi inverter system reads how many elements are connected in communicating mode and calls this number N.
Then, on the basis of parameters NA and NC it decides how many and which inverters must work at a given time. NA represents the
number of inverters involved in pumping NC represents the maximum number of
inverters that can run simultaneously.
In a series, if there are NA active inverters and NC simultaneous inverters, when NC is less than NA, this means that a maximum of
NC inverters will start up simultaneously, and these will switch between NA elements. If an inverter is configured with reserve priority,
it will set as last in the starting order, therefore for example, if there are 3 inverters and one of these is configured as reserve, the
reserve unit will start in third place; otherwise if set to NA=2 the reserve will not start up unless one of the two active units sets to fault
status.
See also the explanation of parameters
NA: Inverter attivi par. 6.6.8.1;
NC: Inverter contemporanei par. 6.6.8.2;
IC: Configurazione della riserva 6.6.8.3.
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