Examples Of Configuration For Multi-Inverter Systems; Et: Exchange Time; Cf: Carrier Frequency; Ac: Acceleration - DAB PWM II 230 D 4.7 Instructions Pour L'installation Et La Maintenance

Inverters configured as reserve, even though not part of the normal pumping process, are still kept efficient by means
of the anti-stagnant algorithm. The anti-stagnant algorithm envisages, once every 23 hours, the exchange of start-up
priority, to ensure that each inverter accumulates at least one minute of continuous flow. This algorithm aims at
avoiding deterioration of the water in the impeller and to maintain efficiency of moving parts; it is useful for all inverters
and in particular for the inverters configured as reserve, which do not operate in normal conditions.

6.6.8.4 Examples of configuration for multi-inverter systems

Example 1:
A pump set comprising 2 inverters (N=2 detected automatically) of which 1 is set as active (NA=1), one simultaneous
(NC=1 or NC=NA provided that NA=1) and one as reserve (IC=reserve on one of the two inverters).
The effect is as follows: the inverter not configured as reserve starts up and runs alone (even if it cannot withstand the
hydraulic load and the pressure is too low). In the event of a fault, the reserve inverter is started up.
Example 2:
A pump set comprising 2 inverters (N=2 detected automatically) of which all inverters are active and simultaneous
(default setting NA=N and NC=NA) and one as reserve (IC=reserve on one of the two inverters).
The effect is as follows: the inverter not configured as reserve always starts up first; if the pressure reached is too low,
the second inverter, configured as reserve, also starts up. In this way, the use of one inverter in particular is preserved
(the inverter configured as reserve), but is always available as a support when necessary in the event of increased
hydraulic loads.
Example 3:
A pump set comprising 6 inverters (N=6 detected automatically) of which 4 are set as active (NA=4), 3 simultaneous
(NC=3) and 2 as reserve (IC=reserve on two inverters).
The effect is as follows: a maximum of 3 inverters start up simultaneously. Operation of the 3 inverters enabled for
simultaneous mode is implemented in rotation between the 4 inverters to remain within the maximum operating time of
each ET. In the event of a fault on one of the active inverters, no reserve unit is started up as no more than three
inverters can be started up at a time (NC=3) and there are still three active inverters present. The first reserve unit
intervenes only when one of the remaining three has a fault; the second reserve is started up when another of the
three (including the first reserve) has a fault.

6.6.9 ET: Exchange time

This sets the maximum continuous operating time of an inverter within a group. It is only applicable on pump sets with
interconnected inverters (link). The time can be set to between 10 s and 9 hours, or to 0; the factory setting is 2 hours.
When the time ET of an inverter has elapsed, the system starting order is re-assigned so that the "expired" inverter is
set to minimum priority. This strategy aims at reducing use of the inverter that has already been in operation, and to
balance operating times of the various units in the group. Despite assignment as the last unit in the starting order, if
the hydraulic load requires intervention of this specific inverter, it is started up to guarantee adequate system
pressure.
The starting priority is re-assigned in two conditions, according to the time ET:
1) Exchange during pumping process: when the pump is active continuously through to exceeding the maximum
absolute pumping time.
2) Exchange on standby: when the pump is on standby but 50% of the time ET has been exceeded.
If ET is set to 0, exchange occurs on standby. Each time a pump in the group stops, a different pump will be activated
on restart.
If the parameter ET (maximum working time) is set to 0, exchange occurs on each restart, regardless of
the effective working time of the pump.

6.6.10 CF: Carrier frequency

This sets the carrier frequency of the inverter modulation. The value set as default, is the correct value in most cases,
and therefore modifications are not recommended unless fully aware of the changes made.

6.6.11 AC: Acceleration

This sets the speed of variation with which the inverter varies frequency. This acts both on the start-up phase and
during control. In general, the pre-set value is optimal, but in the event of problems during start-up or HP errors, it can
be modified or reduced as required. Each time this parameter is modified, it is advisable to check that system control
is still efficient. In the event of problems of oscillation, lower the GI and GP gain values; see paragraphs 6.6.5 and
6.6.4. A reduction to AC will slow down the inverter.

6.6.12 AY: Anti cycling

This function avoids frequent switching on and off in the case of leaks in the system. The function can be enabled in 2
different modes: normal and smart.
In normal mode the electronic control blocks the motor after N identical start/stop cycles. In smart mode it acts on the
parameter RP to reduce the negative effects due to leaks. If set on "Disable", the function does not intervene.
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