Document Ldp6yR06bz2gv2om77GE3bm3

However, the instantaneous drop in voltage which occurs during this period can be followed by a rapid decline in synchronizing power in the transmissionsystem. Thus, a momen tary fault on a line between a gen erating plant and a load area might cause the plant to pull out of syn chronism with the load and cause a breakup of the system. To prevent this, the synchronous condensers are ready, at the instant of a fault, to deliver large blocks of leading re active kva which compensates for the lagging kva that usually feeds into ratio, a shaft-driven main exciter, a motor-driven pilot exciter with special field windings, and an electronic voltage regulator were used. The condenser field is supplied from the main exciter which has two shunt fields. One field is supplied with constant potential d-c; the other receives variable d-c voltages from the pilot exciter. The pilot exciter, in turn, has tw-o shunt fields, one a "biasing" field, and the other de signed to receive signal voltages from the electronic regulator. The photo, page 28, shows the electronic Simplifiedfloat plan nj the auxiliary control housing. the fault. In fact, the Bonneville condensers, hy virtue of their special design, can on short notice deliver 200 percent of their 15 psi leading kilovar rating--a momentary ca pacity of 120,000 kva. High-speed excitation system Each of the Bonneville condensers is equipped with an unusually high speed excitation system. System re quirements demanded that each unit be capable of delivering a short-time capacity of200 percent for lOseconds. This required an ASA response ratio of 5.0 rather than the conven tional ratio of 1.0. Actually, tests made on the condensers after instal lation established a short-time capa city of 120,000 kva (140 percent) and an ASA response ratio of 6.0, considerably above the requirements. To achieve this high ASA response regulator, mounted in itssteel cubicle. Design features In each of the condenser instal lations, the controls and auxiliaries which normally arc placed in a pit beneath the condenser arc located in an above-ground auxiliary housing. The condenser rests on a simple rein forced concrete base. This design re sults in considerable reduction in foundation expense. Special attention was given to the fact that it would be necessary to disassemble these large condensers without the aid of a crane. Any attempt to lift the large rotors, weighing more than 65 tons, would obviously present a serious problem. Hence, each condenser foundation is provided with extended soleplates, along which the end domes and stator sections of the condenser can be moved with the aid of small roller assemblies inserted beneath the feet of these parts. With the aid of a lare rotor support beam and tripod assembly, the end domes and stator can be removed without moving the rotor. Thus the handling equipmi-m provided with these condensers makes it possible to conduct normal main tenance and disassembly without disturbing the rotor. Heat is removed from the con denser by two gas-to-water heat ex changers, each located laterally in the lower section of the end dome. Circulation of gas through the condenser is maintained bv large shrouded-type fans at each end of the rotor. A uniform system of cooling is achieved with this arrangement. The exciter, mounted in its own compartment within the condenser shell, is cooled by circulation of hvdrogen gas within its enclosure, bv means of its own shaft fan. A gas-to gas heat exchanger, located directh above the exciter compartment, transfers heat from this compart ment directly into the main vend lating system of the condenser. To facilitate visual inspection o such parts as collector rings, e.xciter commutator, and bearing pedestals, series of viewing windows have beei located in the end domes and excite compartments. Adjacent to cac. viewing window is a suitably locate lamp housing of explosion-proof cor struction. The lamp housings are s arranged that lamps can be change from outside the housing. By pain ing the interior of the end don sections egg-shell white, visibili' within the end dome has been great enhanced. The Elliott Company is proi to have been selected to develi the high-response excitation svste which has operated so successful with these condensers under t rather unique conditions establish by the Bonneville Administratic Each of the units has performed designed, fully meeting ihc expec tions of the user. 30 POWERFAX, SUMMER 1