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Issue link: https://uscgproceedings.epubxp.com/i/149372
Engineering A nswers 1. A. lowpressure I ncorrectanswer.Drainsfromaship'swhistlesteamseparatoraretoohottobedrainedtothelowpressuredrainssystemduetotherelativelyhighsupplypressure(150psig).Drainagetothissystemwould causetheatmosphericdrainstankcontentstooverheatandfashover. orrect answer. Drainsfromaship'swhistlesteamseparatormustbedrainedtothehighpressuredrains C systemduetothehightemperatureofthedrains. I ncorrectanswer.Thereisnodedicatedmainturbinedrainsystem.Thedesignandoperationofthemain turbinerequiresseparatedrainsystemsforhighandlowpressuredrains. I ncorrectanswer.Drainsfromaship'swhistlesteamseparatoraretoohottobedrainedtothecontaminateddrainssystemduetotherelativelyhighsupplypressure(150psig).Additionally,theship'swhistle steamseparatordrainsarenotsubjecttooilcontamination. B. highpressure C. mainturbine D. contaminated 2. Note: The data nameplate on an induction motor lists the rated horsepower, which is the power it is capable of developing without overheating. In addition, the rated RPM and the rated amperage values are listed on the nameplate. The rated values of RPM and amperage are the values associated with the induction motor when developing the rated horsepower. Although torque is not generally listed on a motor's data nameplate, rated torque is torque that is produced when the motor is developing its rated horsepower. When an induction motor is developing less than its rated horsepower, the RPM will be higher than the rated RPM (but less than the synchronous RPM), the amperage draw will be lower than its rated current, and the torque will be less than its rated torque. Similarly, when an induction motor is developing more than its rated horsepower, the RPM will be lower than the rated RPM, the amperage draw will be higher than its rated current, and the torque will be higher than its rated torque. A. powerrequiredto drive the load B. speedrequiredto drive the load C. currentfowin the motor stator D. 3. torquedeveloped bytherotating feld Correct answer. Seetheexplanationinthenoteabove. Incorrectanswer.Althoughspeeddoeschangewithchangesinload(thegreatertheload,thegreater theslip),themotoradjustsitselftoproduceexactlytheamountofpowerrequiredtodrivetheload. Incorrectanswer.Althoughcurrentdrawdoeschangewithchangesinload(thegreatertheload,the greatertheslip,thegreaterthecurrentdraw),themotoradjustsitselftoproduceexactlytheamount ofpowerrequiredtodrivetheload. Incorrectanswer.Althoughdevelopedtorquedoeschangewithchangesinload(thegreatertheload, thegreatertheslip,thegreaterthecurrentdraw,thegreaterthetorque),themotoradjustsitselfto produceexactlytheamountofpowerrequiredtodrivetheload. A. beforetheycanpumpdownthe systeminpreparationforshiftingovertothestandbycondensingunit B. beforetheycansettheoperating controlsofthesystem C. beforeperformingmaintenance, service,orrepairthatcouldreasonably be expected to release Class I or Class II refrigerants into the atmosphere D. beforeperforminganymaintenance or repair regardless of the actualprocedure 92 Proceedings Incorrect answer: Pumping down a system in preparation for shifting over to the standbycondensingunitdoesnotrequireopeningupthesystemandassuchitwould notreasonablybeexpectedtoreleaseClassIorClassIIsubstances.Therefore,thepersondoingthepumpdownisnotconsideredatechnicianundertheventingprohibition rules,thusnocertifcationisrequiredforthisparticulartask. Incorrectanswer:SettingtheoperatingcontrolsofthesystemdoesnotrequireopeningupthesystemandassuchitwouldnotreasonablybeexpectedtoreleaseClassIor ClassIIsubstances.Therefore,thepersonmakingtheadjustmentstothecontrolsisnot considereda"technician"undertheventingprohibitionrules,thusnocertifcationis requiredforthisparticulartask. Correct answer: Thoseperformingsuchmaintenance,service,orrepairactivitiesthat couldbeexpectedtoreleaseClassIorClassIIrefrigerantsareconsideredatechnicianundertheventingprohibitionrules,thuscertifcationisrequired.Examplesof maintenance,service,andrepairactivitiesthatwouldreasonablybeexpectedtorelease ClassIorClassIIsubstancesarethosethatrequireopeningupthesystem(replacinga dehydratorcartridge,chargingthesystemwithrefrigerant,etc.). Incorrectanswer:Onlythoseactivitiesthatwouldbereasonablyexpectedtorelease ClassIorClassIIsubstancesmustbeperformedbyacertifedtechnician.Seeexplanation for choice C. Summer 2013 www.uscg.mil/proceedings