Restoration of service from large metropolitan systems after complete shutdown

L. G. Smith (Consolidated Gas Electric Light and Power Company of Baltimore, Md.): The paper on the Philadelphia system covers the problem of re-energizing a system supplied by both steam and hydroelectric plants and also interconnected with other systems. On such a system it is difficult to formulate a single procedure of restoring service after a complete shutdown. Several procedures must be considered, depending on the relation between hydro and steam generation; the loads in the various load areas at the time of the trouble; and the amount and direction of power flow in the interconnections. The authors have emphasized one point that is believed to be essential: that is, to clear the busses immediately. Whether one or all stations are involved, the busses in the affected stations should be cleared if differential-relay protection has not already accomplished this. This procedure may prevent the spread of the trouble and will facilitate the orderly restoration of service. The need for co-ordination with the boiler operators stressed by the authors is also of vital importance. Any instructions should require the notification of the boiler operators of the load to be restored so that load will not be connected unless it can be carried. This might involve a detailed listing of duties and responsibilities of all operating personnel.