CH2
Chapter 2 · Pumps, fans and compressors
The machines that move fluids, and the drives that make them efficient: pump and system curves, the energy cost of each flow-control method, the five ways to start a motor, soft starters, variable-frequency drives, and pump stations under PID control.
6 lessons· 190 min
- 01Pumps and system curvesThe centrifugal pump curve, the system curve of the pipes it feeds, the operating point where they cross, the affinity laws, and why static head breaks the cube law.30 min
- 02Flow control and energyThrottling, on/off cycling, constant pressure and variable speed compared on the Lab II pump, then fans and compressors: why the drive decides the energy bill.30 min
- 03Starting methodsWhy starting a motor is a problem, and five answers to it: direct on line, star-delta, autotransformer, soft starter and VFD, raced on the same motor and load.35 min
- 04The soft starterAnti-parallel thyristors and phase-angle control: how the firing angle sets the voltage, what that does to torque and current, harmonics, soft stop, and where a soft starter is the wrong choice.25 min
- 05The variable-frequency driveInside a VFD (rectifier, DC link, PWM inverter), V/f control and why it keeps the flux constant, low-speed boost, field weakening above base speed, and the side effects to plan for.35 min
- 06Pump stations: pressure control and stagingHolding a water network at constant pressure with a PI loop on a VFD pump (the live twin of Lab II), why the integral term is needed, and how many pumps a station should run.35 min