单选题When paralleling two AC generators, the frequency of the machine coming on-line, immediately prior to closing its breaker, should be ()Aslightly less than the oncoming generator frequencyBthe same as the bus frequencyCslightly greater than the bus frequencyDthe same as the bus voltage
单选题
When paralleling two AC generators, the frequency of the machine coming on-line, immediately prior to closing its breaker, should be ()
A
slightly less than the oncoming generator frequency
B
the same as the bus frequency
C
slightly greater than the bus frequency
D
the same as the bus voltage
参考解析
解析:
暂无解析
相关考题:
单选题Which condition indicates the air side fouling of an after-cooler on a turbocharged diesel engine?()AAn increased air temperature differential between the cooler inlet and outletBA decrease in the air pressure differential across the coolerCExcessive condensate forming in the air boxDA decrease in the air temperature differential between the cooler inlet and outlet
单选题大型柴油机在拆卸主轴承下瓦时,正确的做法是()。A按发火顺序依次拆卸轴承B每次只允许拆卸一道轴承,待装入后再拆第二道轴承C同时可以拆卸几道轴承,每道轴承必须做好记号D先从自由端开始至飞轮端依次拆卸轴承
单选题Which of the following statements describes one of the functions of the ballast system?()ATo permit flooding of any fuel oil storage tank on any class of shipBTo use it as a secondary service systemCTo store reserve feed or potable water for extended cruisesDTo stabilize the ship by flooding certain designed tanks with seawater
单选题按照我国《钢质海船入级规范》规定,当船舶交流电网的电压、频率发生波动,其稳态值分别在()范围内,交流电器设备能有效地工作。A±10%Un、±5%fnB±5%Un、±10%fnC-6%~+10%Un、±5%fnD-10%~+15%Un、±5%fn
单选题Moisture absorbed in the windings or condensed on the surface of electrical machinery insulation ()Ais good for long term preserving since most insulation is organic and contains some amountBlowers the insulation value and is a common cause of fault grounds in idle machinesCwill enhance insulation resistance only if it is fresh water and contains no saltDreduces the amount of current supplied or drawn by the machine so horsepower is limited
单选题Which statement about satellite navigation is TRUE? ()AWhile a fix can be generated by signals received from two satellites,three satellites are necessary for reliable accuracyBThe satellites are in equatorial orbits around the earth about 60°of longitude apartCThe satellite navigation system determines a fix by measuring the doppler shift of the radio signals from the satelliteDThe ship's receiver cannot begin processing data until the antenna locks onto the satellite and starts continuous tracking
单选题Which of the following conditions would cause carbon deposits to form in the piston ring belt of a diesel engine?()Afaulty combustionBexcessive ring temperatureCover lubricationDall of the above
单选题An alarm device inserted between the deaerating tank and the expansion tank can notify the on-watching crew that ()Athe expansion tank is lack of waterBthe expansion tank is over flowingCthere is something wrong with the cooling systemDthere is something wrong with the engine
单选题根据ISPS规则的有关演习和演练的规定,以下正确的是()。 Ⅰ、为确保有效实施船舶保安计划的规定,应至少每三个月进行一次演练 Ⅱ、如25%船员变动且在前三个月未参加任何演练,应在变动后1周内进行演练 Ⅲ、可能有CSO、SSO、PFSO等参加的各类演习,至少每年1次AⅠ、Ⅱ对BⅠ、Ⅲ对CⅡ、Ⅲ对D以上都正确
单选题对于柴油机滑油状态监控系统,润滑油油样分析时,一般应先进行油的理化性能分析和光谱分析,然后在此基础上进行()分析,必要时再作()分析。A直读式铁谱仪/分析式铁谱仪B直读式铁谱仪/旋转式铁谱仪C旋转式铁谱仪/分析式铁谱仪D分析式铁谱仪/直读式铁谱仪