Compressor Capacity Control and Speed Modulation Quiz

Capacity control of the compressor is achieved primarily by speed modulation.

When unloading, the compressor’s first action is to reduce speed to slightly above the minimum (surge) speed for the pressure ratio present at the time.

IGVs are variable angle vanes installed in the suction inlet ahead of the first stage impeller. These guide vanes restrict the refrigerant from entering the impeller inlet, as well as imparting a “pre swirl” of the refrigerant in the direction of impeller rotation to increase energy efficiency during part load operation.

<p>Speed modulation is achieved by the use of “Inverter” control. To accomplish this, the incoming 3-phase AC supply is converted to high voltage DC, incorporating smoothing/storage capacitors, and then switched by the Inverter, utilizing 3-phase rectifiers, to give a simulated 3-phase AC supply of variable voltage and frequency.</p> Signup and view all the answers

<p>Converting the incoming 3-phase AC supply to high voltage DC incorporates smoothing/storage capacitors, and then switched by the Inverter, utilizing 3-phase rectifiers, to give a simulated 3-phase AC supply of variable voltage and frequency to achieve speed modulation.</p> Signup and view all the answers