Document rBvbXkjG9EKL8MVOjk9OO0jXv

141 H$5o| To determine the teccadarr the following formula U uM<). Beco&dary Amp bp x 749 V3 open-drciilunng Toluj; ///K mutt decide what anto| t*-- and apeed are accessary for the ]2? Both these factors Influence the niZ of aeeondary resistance used, sine* ft!! ore dependent upon the current plied the motor. The secondary rent may then be computed from ft. above equation oftcr subitiluiiag ft, required starting horsepower. Oats the value of the current hat been ^ puted. the necessary reaiitance may ^ found by Ohm's low. Crid cross-sectional area may be cal culated by use of ibe physical eonitsnu end resiiunee relations, which cao be found in Marie's Mechanical Enginttrf Handbook, With this data on JHY can readily determine the reaUtori to give the necessary starting torqm and speed. Before purchasing new reaiaton r sitering the existing devices it would be worth while for him to check with1 the manufacturer o( the motor. Tba. builder can usually supply specific bt-\ formation regording any piece of equip-' ment Tyler C Hicks* Now York Qty,, Simple Test Outlined l , I axsuaiB tost JHY has token op with ' the manufacturer the matter of tbs'; wrong control resistors. To calcuUts secondary resistance for a tliprisg mo-',' tor, the locked rotor volts and full-load secondary amperes must be known, as well as the torque required on the &nl point of the controller. The latter nut be approximated if necessary* f- Locked-rotor secondary voltage is oh *, tained by raising the brushes off lbs sliprings end applying normal lioe volt- age to the stator. Read the rolui#;. across the sliprings with the brushes j; raised. The rotor may be considered ; as a generator changing the electrical j power tronsferred across the sir gsp into mechanical power As a generator - It will develop electrical -power equal , to E * / x V3 a (1-allp); With S d* \ value of the locked>rotor voltage; / Ik ' secondary amperes at lull load and la this cose given as 190 amp, the factor ^ (l-Up) is the efficiency o( the retw- i.' Mechanical power output must equal | the electrleal power generated In the ^ rotor less the rotor losses. From (bis, B, m - hfX?46 / /, X 1.73 X .8 > which equals 315 volts. Gordon Fox la ; his book, Electric Motors and Ccntrd>> ; says: The formula for determination oi < Y-connecled balanced 3-pbaie second- v POWER April High Strength You see here the results ol tests on Haynes high* temperature elloys as compared with stainless,low-alloy, and low-carbon steels. Because of their high-temperature strength, these alloys have been used lor a variety J of parts, such as aircraft turbine blades and buckets, and heat-treating furnace parts. Haynbs alloys hove good resistance to thermal shock and a low creep rote at high temperatures. They also* hove excellent tensile strength--ranging from 45,000 to 70.000 psi at 1500 ddg. F. And this strength is maintained' and enhanced through the aging characteristics that1 occur in the rango of 1300 to 2000 deg. F. The alloys are also resistant to oxidizing ond reducing otmospheres at; these temperatures. You can obtain Haynes high-temperature alloys-sold: under (he trade-marks Haynes Stblute, Hastellov, and Multimbt--in tho form of< precision castings, or as1 sand castings, bar stock, sheet, welding rod, and cast; coated electrodes. Write to ony District Office for further information on those high-temperature alloys. Or, (or on-the-job help, ask to have a representative call. fe-- r \1 (Own April 1,41 : V v-r-'-'-ir Haynes Stellite Company Unit ff (Jnttn CorM* end Ctrbi Cirymtft* 033; General Office* and Work's, Kokomo, Indiana Settt OfUtt Chka#a--CUtxIaMd--Ottrek--Haostaa--Lai AaltWi New YaX--Fniicliw-TolM and*'MuiiiMt*l*Si*tlaiubti p*a4*ct* at Hayne* SariUtt Ceiayaay.