Generator Voltage Problem

Please see the attached file. We have 100 MW steam TG set. It was running at 80 Mw and stopped ( normal procedure ) to attend small oil leak in oil circuit. After starting itwe did not get terminal voltage ( PT second .110 volys in all the three phase . PT 12 KV / 110 V is perfectly O.K. . Mail exciter field getting voltah and showing current _ from AVR/MVR (PMG o.k. giving output to AVR/MVR ) . further investigations.test are shown in the attcahed file refering to sketch given therein.( How to attache attachement to the question ? )

Request further investifgation suggestion/ solutions etcc..