answered 2019-01-16 02:00:46 -0500
Use inibrn and nxtbrn3, for example, to loop all branches and transfomers connected to ibus:
ibus = 154 ierr = psspy.inibrn(ibus, 2) while True: ierr, jbus, kbus, ickt = psspy.nxtbrn3(ibus) if ierr>0: break