DAB PUMPS PWM 203, Instruction For Installation And Maintenance

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O1 Output 1 function
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O2 Output 2 function
4.4 Initial start-up of multiple inverter system
Make electrical and hydraulic connections of the entire system as described in para 2.2 and para 4.2.
Switch on one inverter at a time and configure the parameters as described in chapter 5 taking care that when turning on one
inverter, all others are switched off.
After configuring all inverters individually, all can be switched on simultaneously.
4.5 Multi-inverter settings
When a multi inverter system is switched on, the addresses are assigned automatically and, by means of an algorithm, an inverter is
nominated as the settings leader. The leader decides on the frequency and order of start-up of each inverter in the series.
The settings mode is sequential (inverters start one at a time). When start-up conditions are enabled, the first inverter starts, and
when this reaches maximum frequency, the next one starts, and so on. The order of start-up is not necessarily ascending according
to the machine address, but depends on the hours of operation; see ET: Tempo di scambio par. 6.6.9.
When the minimum frequency FL is used, and there is only one inverter operative pressure surges may occur. Depending on the
case, pressure surges may be inevitable and may occur at the minimum frequency when this value, in relation to the hydraulic load,
causes a pressure level greater than the required value. On multi inverter systems, this problem remains limited to the first pump that
is started up, as on the subsequent pumps the situation is as follows: when the previous pump reaches the maximum frequency, the
next one starts up at the minimum frequency to then reach the maximum frequency. When the frequency of the pump at maximum is
reduced (obviously through to the minimum frequency limit) the pump activation overlaps, which while observing minimum frequency
rates, does not cause pressure surges.
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.