Document LK5DY5qpgLr5n13z59db4dZ95

More TECHNICAL BRIEFS. IT NEW DEMANDS goverciori, apeed matching, automatic load and frequency control, penstock valves, circuit operation, audio or ub* carrier equipment channels, emergency control, emergency power supply and other feature* are described. AIEE paper No. 55-94 by the authors of this paper gives operating expo* riencea with these automatic ond super* visory control*. Capital and operating costa, performance of the automatic equipment, automatic plant troubles for 1952, troubles with operation of lamp indications, telemetering and megawatthour counters ore presented. AIEE Paper No. 53-95. Prime Movers Prime Meyer Speed Governor* and the Interconnected System, fly P.-Xr fpsen and J R Norton, General Elfbric Co. The operators of power generating equipment havo long been aware of the foci that it would be desirable from a system control point of view to Have oil speed governors on their intercom necied systems with reasonably similar steady-state characteristics. Normal load changes would then bo shared by all units in proportion to their ratings and the action of supplementary con* trollera would be uniform. This would make ayatem control simpler and would result in smaller deviation of frequency and load distribution from the desired values. In most cases, attempts to make all prime movers on a system respond to system changes In proportion to their ratings have been ` confined to setting all the speed governor* so that they hove equal steady state speed regulation. Tests show that the response of prime movers to change* in system frequency or to the action of supplementary eon. trailers is of a random nature and bears little relation to machine rating or to iteady-stafo speed regulation. This pa per. will outline the factor* that con tribute to the random nature of prime mover response and indicate how test* ing programs for existing units, as well as future design changes of governing systems, can produce a major improve* ment. The behavior of the speed governing systems on turbines in an intercon nected power system can be under stood only by defining and measuring their characteristics. These are defined in the AIEE 600 Recommended Specifi cation, published in 1949. The more Important characteristics ore given be low: a. Steady State Speed Regulation {* the change in speed when the power output of the turbine is gradually re duced from rated power output to zero power output with identical settings of all adjustments of the speed governing system, h is expressed in per cent of' rated speed. b. Steady State Incremental Speed Regulation is the rata of change of steady state speed with respect to power output at a given steady state spoed and power output. It.is expressed in per cent of rated speed when the dif ference is sustained speed, expressed in per cent of rated epeed, for any two !% The figure shows one type'*? governing system for a stsam.tfi; The modem governor U desInSt operate with a minimum oj frie^r the speed sensing element UjSS to move only a imoll pilot valve 5L in oil under pressure. It, amplified many times by the tir* relays. Dead band and lacreroeatafyf lation values should easily then! recommended specifications. i/rtf per No. 55-55. Permanent Magnet Fractional hS power Motors end Generator*, fly*)3 points on the tangent, divided by the ley R Goss, General Electric Co.C' corresponding difference in power out* The evolution of use of perms put expressed as a fraction of rated magnet materials in rotating matbi power output. Is ehiefly one of magnet materiel), c. Dead Band is.the total magnitude methods of processing and d&*|\t ' of the sustained speed change within material. About twenty years igo1 which there is no resulting change In position of tho governor controlled valves. nieo number II was beginning. produced for commercial uaags.^ ' About 1945 we designed a a'c^ d. Stability is the capability of the peed governing system to position tbe governor controlled valves so that a sus tained oscillation of turbine speed or energy input to the turbine is not produced by the governing system dur ing operation under sustained load de mand or following a change to a new sustained load demand. c. Overspeed Is the maximum increase in speed from rated epeed following a sudden reduction of turbine power out put. Overspeed is expressed in per cent of rated speed. Instrumenta are available which make it possible to determine any of these characteristics with reasonable accuracy. The performance of a governing system for a prime mover Is most readily an alysed If it is considered to consist of two primary elements. 1. The speed sensing element or governor head ond its relays Including the servomotor. 2The control valves which are positioned by the servomotor. of ac alternators having multiple'^ rotating magnetic fields. These - first designed with smooth roih____ pole, permanent magnets on which*! polarity was' impressed daring tnagu^ tiling. These magnets were vcry'diM cult to heat treat and had to bs'miE netixed, all pole* simultaneously iotf multiple pole magnetiser. TbesttnE chines had very good wave fonnr'esti post* but the magnet was not efficients used due to the relatively short len^j between poles -thot could be nugnctimfi effectively. ` $8 At first these machines were etstSfij steel sleeves with screw inserti wUgj caused considerable amount of crai ing in the magnets: To reinforce cracked magnets, each one was .iojL rounded with a stainless steel, noa-tUn netic banding ring on each end ef 't^ rotor. In order to eliminate this d^j culty, a solid cast magnet without^ serts was mounted by casting it iarffl aluminum jacket. This construction to satisfactory mechanically but raqqljj*J die costing equipment that was not eejj TO OBTAIN COMPLETE TEXT nomleal for small productionwere still inefficient magnetically Material for these abstracts comes from the following source unless otherwise staled. Order complete paper from source, not Power. American Institute of Electrical Engineers, winter general meet ing,. Sutler Hotel, New York, N. Y. Jan 19 23, 1953. Identified by initials AIEE end obtainable through AIEE, 33 V 39th St, New York 18, N. Y. de-magnetiied quite easily, In use the magnetic material more #5 ciently, a redesign was roede. In Mfa construction, the flux was collected-W a steel ring and fed to the sir FQ through fingers; ell the North poja being fed from ono end of the mspj5 and oil the South poles from the PPg| site end of the magnet. This magnet more uniform In cross and length and was cosily esit, netired end heat treated. In wsa^i (Continued on page 2&) HEAP!* Hltvict StCTION Affords Maximum Safe Kilowatt Output at An/ Power Factor Loading jjj||l0WiNG pains are taxing your plant productivity pr. if ever-increasing demands require closer regula tor your present generating equipment, consider _ Jr/ftW efficiency gained by installing a Rtguftx volt* Ep.regulator. fl&Auiomitic minimum excitation provided by the RegK&.volUge regulator permits generator operation close stability limit.. . much closer than manual operafallows. The sensitivity tad exceptional response of the Rtguhjt voltage regulator and associated equipment establish and maintain a safe ratio between generator ' load and field current. . , increase operating limits at any given power factor load. assure the best reactive kva division. This means maximum kilowatt output -- more power to sell from your present capacity. Get all the facts from your A-C representative or write Aifis-Chalmers, Milwaukee 1, Wisconsin. A.401| (*yvf* It it Allli-Owlnirt mWitirt. ALLIS-CHALMERS 159