SYNCHRONOUS MACHINES - Open circuit & Short circuit tests - SEE 3433 MESIN ELEKTRIK SYNCHRONOUS MACHINES - Open circuit & Short circuit tests -

These tests are conducted to determine the synchronous reactance of a synchronous machine Conducted in SEE 3742 Electrical Machine Laboratory

Stator terminals open  Ia = 0  Vt = Ef Open-circuit test Open Circuit Characteristic (OCC) Rotor runs at constant speed – field current adjusted  Ef depends only on flux per pole or If Stator terminals open  Ia = 0  Vt = Ef Air-gap line Ef, Modified air-gap line Excitation voltage with no saturation OCC Vt,rated Magnetic saturation If

No saturation since airgap flux is small Short-circuit test Short Circuit Characteristic (SCC) Rotor runs at synchronous speed - stator terminals shorted – stator current plotted against If No saturation since airgap flux is small Ef, Ia OCC Vt,rated SCC If

Determining Xs OCC Vt,rated Ef, If Ia SCC

Determining Xs If’’ If’ Synchronous reactance, Xs = Ia,rated Ia’ Ef, OCC Vt,rated SCC Ia,rated If’’ Ia’ If Synchronous reactance, Xs =