Document emJoY8yJG1aq1ZakkaM4jy93G

1 'if Hr bl/l Check With Synchroscope Clow-stick method of checking lor re versal o( phase, which JR describes, is satisfactory provided the three phases II r but fclHMlfermtrM ftMte Ocb 4M -- ore tested simultaneously. Although this ' method is reliable, it presents a definite / 1 Prl tut* //---y -y^ Ocb """k .hazard to the.operator. Rather than the method he now uses, I suggest JR adapt the synchroscope on his control board for phasing out. This method may be readily used If Hie ' W-H Dlttonnccli ekutd WMwJ| -f \--H station bus is seciionstized. Let us take the case where the feeder in question Po*r Station comes from section A ol the power- station bus. During a lig^it load period, all feeds from and to that bus section Use Ring-Out Teat Wlth i j ore dropped of! and the ocb opened be tween sections A and B. The feeder In 7. Open 11-kv disconnects end dis question, energized from the substation mantle teet connection*. end, is now closed in on section A. 8. Return line to service. We now hove section A fed through Note that each step of tbia procedure, substation bus which, in turn, is sup check* the preceding step. That is, step plied from section B of power-station 2 checks continuity of wiring and lamp bus. Since each section of bus has its filaments; step 3, the connections; step own instrument transformers connected 4 checks tempi before step S, which ii to synchroscope plugs on control board, the actual operation of phasing out. - the problem now is to check that aection It is assumed that station synchro* A end B arc in synchronism. After this scope is not connected to ll*kv lines. If check, remaining,feeders and generator it were, JR could use it for phasing out to that section of bus are returned to the repaired line.--E E Jones, Cordeno, service.--K It Hoffman, Tenafly, N, J. Calif. JR can out CHECK phasing of ca with a potential transformer. Conir one transformer primary lead to phase on bus side of open ocb and o'i primary lead to corresponding phase' cable side as in above sketch. EaeriuE cable from substation end. If cable is in phase with bus no rent will flow through transformer' mary winding.- Hence a lamp or 1 meter connected across secondary`;uc will not indicate voltage. All tlu phases must be checked in the manner. Where it is possible to ditconni cable at each e~J, a simple syatet Transformers and Lamps. Best mbtkod I know to eheck phase re* versal is use of simple incandescent lamp in conjunction with polenliol transformers. This is essentially same method usod to synchronize two ac generators. Three transformers should be used with primary of each connected across Check With Small Motor Simplest way for JR to check for phase reversal is to hook up a small 3-phasc motor through potential transformers. Knowing rotation of this motor when connected to bus, it is simple to eheck eable phase rotation (sketch below). lettering phases at terminal points^ further simplify the phasing probf Whan cable is so marked, a low dc age may be used with a test lamp, series with one line, the other linear neeted to cable sheath. At other rad cable, that same lead may be fouod' use of voltmeter or test lamp coanej between cable sheath and lead.mere, Memphis, Tenn. the open disconnects at power-station end. When both power-etotion bus and feeder have the eame phase rotation, lamps will not light--James J Ander son, St Paul, Minn. Test With Bus Transforn.- I 8UCCC9T JR use a voltmeter In/: junction with a potential truufor instead of a glow stick if he contig Marti Phases Beforehand this test method. The disconnect Ur" be closed on one phase and voj I succut JR check phase reversal by installing potential transformers on ppwer.transformer aide of power-station disconnects; a small 3-phase motor con nected across secondaries (hooked in open delta) will give indication of phase rotation. If JR painu an identifying letter on each phase at both ends of every cable, be can use a simple "ringing out" teat to check for phase reversal. In this ease the test is made between the secondary of the power transformer and the sub station ocb.--lro A Butcher, Finer River, Va. All leads from potential transformer secondaries could be brought to one point and motor with geared hand oh a dial connected through interlocking switches. The tamo idea could be uaed with phase rotation indicators using resistors, reactors and lamps. I believe . the motor gives an indication the oper ator is less liable to mistake.---E A .Roberts, Carlsbad, N. M. measured, across the two open di necta. In this teat a eingle-phasa i; meat transformer should be used- memberlng that it will he subjra|. about twice normal voltage In casejjl reversed phase In feeder. Since there Is probably a 3-pha*j7* strument transformer on bus, 1 mend a second transformer be coocr 'on transformer side of disconnect*, permanent connection Is msde s. one - phase on the secondary. } meter is connected. In turn, across two phases. Cheek transformer P' lies.--P Vanllwk, Liege, Delii"18 '*110 (560) POWER* Ssplsrub*', During the last two summers the equipment stood -idle for n few months, exposed to inevitable con densation. Inspected recently, the gears end bearings showed no measurable wear, and were free from rust and corrosion, despite the intermittent operation. The oil is in excellent condition, al though never changed. In all major industries, similar excellent results are being obtained by companies which have adopted Sunvis900 Oils for preventive main tenance. Sunvls 900 Oils are forti fied to resist deterioration and to protect metal parte against rusting and corrosion. Theee long-lasting, top-quality oils keep productive meehinery running longer. They , can do the same for you. Call your nearest 8un Office, or--for a copy of the illustrated booklet "Sunvia 900 Oils"--write Department P-9. SUN 0ft COMPANY Ptfadetphia 3, As, tn Conoco, Sum OQ Coapnf, ltd. JJN PETROLEUM PRODUCTS -1VIOB PROVED" IN EVERY INDUSTRY