METHOD OF CASCADE START OF ELECTRICALLY DRIVEN PUMPS IN PRESSURE BOOSTER SYSTEMS WITH FREQUENCY CONVERTER AS A REGULATOR Russian patent published in 2017 - IPC F04D15/00 F04D13/12 

FIELD: engines and pumps.

SUBSTANCE: invention can be used to start the pumps in pressure booster systems, consisting of a group of electrically driven pumps of 0.4 kW and a frequency converter (FC) as controller. The method includes selecting the first start priority pump of the totality of the installation pumps and its start-up from the FC with control according to the characteristics supply voltage - AC frequency. Then the first additional pump is selected, which is the second in start priority, its start with lowering the pressure in the pressure main below the specified using the method of direct start or a semiconductor soft starter, or using the starters with scheme "star-delta", and after start, the pump works in the constant performance mode. Then the second additional pump is selected, which is the third in start priority, it is started with lowering the pressure in the pressure main below the specified from the FC by switching the FC to it from the first start priority regulated pump. To do this, the disconnected from the FC, the first start priority pump is connected after a certain period of time to the power supply network and said time interval is determined by the pump autorotation allowable time as a function of the active power of the pump motor. The pump newly connected to the FC becomes adjustable according to the characteristics supply voltage - AC frequency. Similarly, the other pumps are started.

EFFECT: hydraulic impact reduction in the consumer pressure main and the inrush current in the power supply network, eliminating static errors of the control process, caused by pumps switching by changing the controlled pump priority.

1 dwg, 2 ex