We performed a pole drop test and then seperated the pole connections, everything was uniform. We cleaned and heated the rotor, the resistance improved for a short period of time then dropped again. The condition is slightly better when this unit is on line alone, then gets worse as the other...
This unit is 10.5 mw, the AVR is Eaton dualbridge (main & redundant) scr firing. My fault in using "high" frequency, it is 30-40 cps and the megger reading was K ohms, I wish it was Mohms. We recently had Eatons field rep in to check tuning, the two 125vdc machines are identical and this problem...
We have 3 hydor units rewound, with new solid state exciters, 2-125vdc machines and 1-250vdc. Through trending software in SCADA, field current for a 125vdc and 250vdc units are stable with very little corrections made. The other 125vdc unit has a high frequency ocillation at an amplitude of 15...
