incorporated an advance alarm system with the tripping system which covers the thought expressed by Mr. Gaskins in the comment where he questions the necessity of tripping to prevent exhaust-hood and condenser-shell damage. We wish to point out first that the exhaust hood temperature rise will be rapid in the event of loss of desuperheating water under light-load conditions and also that, second, this device provides a second line of defense in case of loss of vacuum. It is interesting to note here that the condenser manufacturer stated that he could not predict what damage might result to the condenser if the exhaust temperature should exceed 230 (F).As to Mr. Gaskins' comment on excessive furnace and flue pressure trips, that his company's experience with pressure operating switches has been very poor and he is interested in knowing if Consolidated Edison has had similar difficulties, we can report that we agree with him. The manufacturer of the Astoria pressurized boiler recommended use of pressure switches. We have found the diaphragm type to be much more reliable than other designs. Proper cleanout facilities for cleaning the tube connected to the furnace must be provided.In regard to Mr. Gaskins' discussion of the complete interruption of all fuel, the authors' company considered the type of governor control which Mr. Gaskins described, but concluded that in instances of complete loss of fuel it is safer from the standpoint of avoiding possible furnace explosions and to avoid possible overstressing of the high temperature parts of the turbine cylinder and the development of axial rubs between the spindle and the cylinder, to trip the unit completely in such cases. The boiler would then be purged and a quick start would be made on the turbine and boiler under controlled conditions. Mr. McKenna, Mr. Gaskins, and Mr. Keeth referred to the use of time delay with the generator motoring relay. We see no objection to this and in fact will probably adopt time delay for the generator motoring relay on the next main generating unit installation. We have never experienced incorrect tripout by a generator motoring re-lay when synchronizing, due to the generator coming in "slow", because of the use of a switch contact on the regular generator synchronizing switch.In reference to Mr. Keeth's thought that some of the protective devices are possibly the outgrowth of necessity arising from the program of quick-starting of boilers and turbines, the authors' automatic tripping devices used during normal operation are completely independent of the automatic tripout features provided in the quick-start part of the protective system. After a quick start is made on the Astoria units, the tripping devices which are provided for the quick-start part of the operation are made inoperative shortly after the unit is loaded. An interesting thought at this point is that the ability to make quick starts lessens greatly the objections to increased exposure to unnecessary tripping caused by the introduction of more automatic trip devices.Mr...

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