What is shunt capacitor?

Connected in parallel with the system to reduce overcurrent/losses

An AC (non-polarized), usually high voltage capacitor that is connected in

parallel with an inductive Motor (and very close to the motor, or other

inductive load) to help reduce Reactive Power (Magnetizing AMPS)

which do no real work but only cause extra heat in the wiring and motor

as there is a Lagging Current Phase Angle created by an Inductor and a

Leading Current Phase Angle created by a capacitor which helps correct

the impedance mismatch between line and load.

google "Reactive Power" and/or "ELI ICE man" for more information.