Niagara Falls 100.000-Hp. Development

Niagara Falls 100,000 Hp. Development [35 The estimated weights of the principal parts in pounds are as follows: ____________________________ _________ ____________ No. 16 No. 17 No. 18 224,000 251,000 291,000 271,000 311,000 318,000 90,000 53,000 41,000 585,000 615,000 650,000 Stator with core and windings ..... Rotor with shaft............. Miscellaneous parts.......... Total .................... ___________________ _________________________ In each case the weight of the revolving part is carried by a Kingsbury thrust bearing mounted upon a massive spider on the top of the generator. These bearings are identical in the three different machines furnished by the various manufacturers. Mica insulation was used for the armature windings of all three machines. Rotors were all designed for 100 per cent overspeed. Guaranteed efficiencies at normal load were 97 to 97.25 per cent and armature reactances not less than 18 per cent at the maximum generator rating. Alternative Sources of Excitation Provided for Each Generator An in dividual motor-driven exciter is provided for each generator. The motors are 2,200 volt, three phase, 25 cycle, 750 r.p.m.; the exciters 220 volt, 225 kw. shunt wound with series interpoles. house. The exciter motors are started from the unit switchboards on the gallery. Eighteen Temperature Detectors in Each Generator Each machine is equipped with eighteen embedded temperature detectors, whose leads are brought to ter- minals on the exciter switchboards, from which any six can be connected to temperature indicating devices in the control room. Cooling air is taken by the gen- erators from the generator room at both top and bot- tom of the machine. The hot air discharging through the ventilating ducts is collected by a plate steel hous- ing completely surrounding the generator frame and connecting to the inlet of a large motor-driven blower which exhausts the hot air, discharging it through a duct below the power house floor to an uptake leading to the outer air at the roof. Thus the hot air delivered from the generators is not permitted to enter the gen- erator room. Means are provided, however, for recir- culating any desired portion of this air during cold weather for the purpose of maintaining- the tempera- ture of the generator room at any comfortable working temperature desired. The generators are protected as to internal break- downs by means of the Merz-Price system of relays FIG. 48—END VIEW OF OPERATING GALLERY AND SECTION OF EQUIPMENT BELOW IT There are two alternative sources of supply for the exciter motors. (See the general wiring diagram.) One of these comes from a special 2,200-volt waterwheel- driven generator installed for this service; the other is connected through transformers to the 12,000-volt buses of Station 3. Provision is made for a third connection to the present 2,200-volt distribution circuits in Station 3 gate house. As a further reserve, there is also an auxiliary field circuit connecting to the direct-current buses of Sta- tion 3, capable of supplying the field of any one of the three new machines through a single field rheostat and direct-current bus. A controller for this rheostat is placed on the control board of each generator in the control room. All of the exciter circuits with the exception of the motor-starting equipment are controlled from the control room at the top of the cliff back of the powei operated from two sets of current transformers, one installed at the neutral point and one in the phase leads, these relays being arranged to trip the line and field circuit breakers simultaneously. Overcurrent relays are also provided to trip the line circuit breakers in case of a short circuit. All relays are of the inverse definite time type. Alarm signals are arranged to give warning of the failure of oil or governor fluid supply or the supply of water for the lubrication of the lignum vitæ turbine bearing. Generator Auxiliaries “Turbo-conoida!” ventilating fans made by the Buf- falo Forge Company and rated at 90,000 cu. ft. per minute are directly connected through Franke flexible couplings to Allis-Chalmers 40-hp., 220-volt, 25-cycle, 288-r.p.m. induction motors. Starter handles are mounted upon the exciter switchboard on the gallery.