Nastec ANDO VASCO - Variable Speed Pumping Unit with One or Two D.O.L. Pumps; Operating Principle

A second splitting method requires installing in parallel a single pump regulated in frequency by the inverter and
one or two other D.O.L. pumps. (Direct On Line) that are switched on or off by the inverter itself through contactors.
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1: Inverter; 2: Pump; 3: Check valve; 4: Pressure vessel; 5: Gate valve; 6: Gate valve; 7: Pressure sensor; 8:
D.O.L. pump control device.
WARNING
The D.O.L. pumps should be controlled by special devices that, besides managing the start and stop,
also ensure the main protections (overload, dry running).
Nastec offers the PILOT device for this purpose.
Finally, it is possible to equip the system with more pumps in COMBO mode, and one or two more D.O.L. pumps
that intervene when more water is required.
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1: Inverter; 2: Pump; 3: Check valve; 4: Pressure vessel; 5: Gate valve; 6: Gate valve; 7: Pressure sensor; 8:
D.O.L. pump control device.
11.2. Variable speed pumping unit with one or two D.O.L. pumps.
11.2.1. Operating principle.
The unit consists of a pump controlled by an inverter, equipped with a pressure sensor, and one or two D.O.L.
pumps that are switched on or off by the inverter itself through contactors.
When there is a water demand, the pump controlled by the inverter (primary pump) is always the first to start up in
the unit. Its speed varies according to demand.
As the demand increases and the maximum frequency is reached, the signal to start the first D.O.L. pump is given.
(D.O.L. pump 1) and at the same time the variable speed pump reduces its frequency.
A further water demand causes an increase in the frequency of the primary pump until, once its maximum
frequency is reached, the signal to start the second D.O.L. pump is given (D.O.L. pump 2).
VASCO - VAriable Speed COntroller
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