Ghalamchi - Rey power Plant AR.P.C
Haeri - Rey power Plant AR.P.C
Masoumi - Rey power Plant AR.P.C

With consideration of highly needs ( Requirements) of Electrical energy production and not having effective spinning reserve in Iran power system,we must minimze.the trip of units until we overcome the ecomo mical point & power supply. Therefore we study three subjects which cause unwanted trip in rey power plant units and we present the following suggestions to overcome these problems for better operation of units. Three subjects for study in these paper are as Follows A-There is not any earth fault protection for the 11KV bus Primary winding of transformer 11/230 KV and Aux. Transformer in Fiat type units.B-The cause of trip in unit no. 6 of Acee type during voltage drop in 11KV generatiors bus and unable to supply enouough oil lubricating pressure during change over system.C-The problem of loss of field protection system in Acee type units.