Proceedings magazine is a communication tool for the Coast Guard's Marine Safety & Security Council. Each quarterly magazine focuses on a specific theme of interest to the marine industry.
Issue link: https://uscgproceedings.epubxp.com/i/57858
A Engineering 1. A. The power factor will change in the lagging direction B. The power factor will change in the leading direction &RUUHFW; $QVZHU 7UDQVIHU RI UHDFWLYH ORDG LV DFFRPSOLVKHG E\ FKDQJLQJ WKH LQGLYLGXDO DOWHUQDWRU ÀHOG H[FLWDWLRQ FXUUHQWV LQ RSSRVLWH GLUHFWLRQV ,QFUHDVLQJ WKH UHDFWLYH ORDG requires increasing the voltage setting of the alternator assuming more reactive load, which will cause the alternator power factor to change in the lagging direction. Incorrect Answer. As stated in choice "A," transfer of reactive load is accomplished E\ FKDQJLQJ WKH LQGLYLGXDO DOWHUQDWRU ÀHOG H[FLWDWLRQ FXUUHQWV LQ RSSRVLWH GLUHFWLRQV Decreasing the reactive load requires decreasing the voltage setting of the alternator giv- ing up reactive load, which will cause the alternator power factor to change in the leading direction. & The kilowatt load will be greatly increased D. The kilowatt load will be greatly decreased 2. A. Adjacent to the piston skirt when WKH FUDQN LV RQ 7'& B. Along the lower part of the liner wall opposite the control ring. & Opposite the top ring shortly after piston travel has ended on the compression stroke. Incorrect Answer. Transfer of kilowatt load is accomplished by changing the individual governor speed settings in opposite directions. Increasing the kilowatt load requires rais- ing the speed setting of the alternator assuming the additional load. ,QFRUUHFW $QVZHU $V VWDWHG LQ FKRLFH ´& µ WUDQVIHU RI NLORZDWW ORDG LV DFFRPSOLVKHG E\ changing the individual governor speed settings in opposite directions. Decreasing the kilowatt load requires lowering the speed setting of the alternator giving up the load. Incorrect Answer. The skirt exerts relatively low thrust upon the cylinder wall. The associ- ated cylinder wall temperatures are relatively low and lubrication of the effected region is relatively easy to achieve. The result is relatively low wear. Incorrect Answer. The oil control ring exerts relatively low thrust upon the cylinder wall. The associated cylinder wall temperatures are lower than the region associated with the compression rings, and lubrication of the effected region is easier to achieve as compared to the compression rings. The result is relatively low wear. &RUUHFW; $QVZHU 7KH WRS FRPSUHVVLRQ ULQJ H[HUWV WKH JUHDWHVW WKUXVW DJDLQVW WKH F\OLQGHU wall. The thrust is maximum when the piston is beginning to move downward on the power stroke. The temperature of the cylinder wall is at its highest and lubrication of the HIIHFWHG UHJLRQ LV GLIÀFXOW WR DFKLHYH DV FRPSDUHG WR WKH RWKHU FRPSUHVVLRQ ULQJV 7KLV results in the region of greatest wear under normal operating conditions. The wear in this region results in the formation of the characteristic "ridge" associated with the top of the cylinder liner. D. Opposite the oil control ring when the crank is on bottom dead center. 3. A. 18 percent ( &RUUHFW; $QVZHU Slip Ratio = E - A (100) ....................E.................... 3URSHOOHU 6SHHG × 3LWFK E = (60 revolutions/minute) (20.07 feet/revolution) E = 1204.2 feet/minute Slip Ratio = 1204.2 - 987.4 (100) ... B. 20.46 percent & 22.10 percent D. 26.20 percent ...........................1204.2........... . = 18 % ,QFRUUHFW $QVZHU &KRLFH; ´$µ LV WKH RQO\ FRUUHFW DQVZHU ,QFRUUHFW $QVZHU &KRLFH; ´$µ LV WKH RQO\ FRUUHFW DQVZHU ,QFRUUHFW $QVZHU &KRLFH; ´$µ LV WKH RQO\ FRUUHFW DQVZHU 4. 1RWH 7KH TXHVWLRQ PDNHV UHIHUHQFH WR &)5 3DUW ZLWKLQ 6XEFKDSWHU ) 0DULQH (QJLQHHULQJ µ7KUHDGHG MRLQWVµ FLWHV DUH IRXQG LQ SDUW § A. 450° Fahrenheit B. 650° Fahrenheit & 825° Fahrenheit D. 80 ,QFRUUHFW $QVZHU &KRLFH; ´'µ LV WKH RQO\ FRUUHFW DQVZHU ,QFRUUHFW $QVZHU &KRLFH; ´'µ LV WKH RQO\ FRUUHFW DQVZHU ,QFRUUHFW $QVZHU &KRLFH; ´'µ LV WKH RQO\ FRUUHFW DQVZHU ° )DKUHQKHLW &RUUHFW; $QVZHU &)5 Proceedings Spring 2012 FRUURVLRQ VKRFN RU YLEUDWLRQ LV H[SHFWHG WR RFFXU RU DW WHPSHUDWXUHV RYHU F VWDWHV ´ 7KUHDGHG MRLQWV PD\ QRW EH XVHG ZKHUH VHYHUH HURVLRQ FUHYLFH ° )DKUHQKHLW µ www.uscg.mil/proceedings HQJLQH GLVWDQFH SHU PLQXWH A = actual distance advanced per minute A = 234.02 nautical miles (6076 feet/mile) ÷ (24 hours) (60 minutes/hour) $ IHHW ¸ $ IHHW PLQXWH PLQXWHV ,QFRUUHFW $QVZHU &KRLFH; ´'µ LV VLPLODU WR &KRLFH; ´%µ DERYH H[FHSW WKDW WKH ORZHVW SDUW RI WKH OLQHU ZDOO RSSRVLWH WKH RLO FRQWURO ULQJ LV VSHFLÀHG 'XH WR SRVLWLRQ DQG HDVH RI OXEULFD- tion, this translates into relatively low wear. n sw e r s