Variable-Frequency Centrifugal Pump Drive Model

Zadatak ovog rada je bio upoznavanje s centrifugalnom pumpom. Centrifugalna pumpa je uređaj kojemu je svrha pomicanje tekućine željenom brzinom od jedne do druge točke sustava. Princip rada centrifugalne pumpe se bazira na Bernoullijevoj jednadžbi za protok tekućina. Q-H karakteristika je najvažnija karakteristika pumpe, a prikazuje ovisnost visine dobave H o protoku tekućine Q. Visina dobave se umjesto tlaka koristi iz razloga što se tlak mijenja s promjenom gustoće tekućine, dok visina dobave ostaje ista. Karakteristika sustava se računa na sličan način kao i karakteristika pumpe uz dodatak gubitaka zbog trenja pri protjecanju tekućine u elementima sustava. Četiri načina upravljanja pumpom su objašnjena u ovom radu: start-stop upravljanje, bypass upravljanje, upravljanje prigušnim ventilom te upravljanje promjenom brzine vrtnje. Laboratorijski model pogona se sastoji od asinkronog motora, sinkronog motora s permanentnim magnetima, frekvencijskih pretvarača te PLC-a. Model pumpe je odabran na temelju asinkronog motora, dok sinkroni motor s permanentnim magnetima predstavlja pumpu. Pomoću laboratorijskog modela pogona je isprogramiran rad pumpe u sustavu te je proučavan rad pumpe uz upravljanje promjenom brzine vrtnje.The task of this labor was to get to know with centrifugal pump. Centrifugal pump is a device which purpose is to move the fluid at desired speed from one point of system to another. The principle of centrifugal pump operation is based on Bernoulli's liquid flow equation. The Q-H characteristic is the most important characteristic of the pump and it shows how pump head H depends on the fluid flow Q. The head is used instead of the pressure because the pressure changes with the change of the liquid density, while head remains the same. The system characteristic is calculated in a similar way as the pump characteristic with added friction losses during fluid flow in elements of the system. There are four modes of pump control that are explained in this labour: start-stop control, bypass control, throttle control and variable speed control. A laboratory model of the drive consists of an asynchronous motor, synchronous motor with permanent magnets, frequency inverters and PLC. The pump model is selected based on an asynchronous motor while the synchronous motor with permanent magnets represents the pump. Using laboratory model od the drive, pump operation in the system is programmed and it is researched with variable speed control