网友您好， 请在下方输入框内输入要搜索的题目：
题目内容
（请给出正确答案）
单选题
Electrical failures in motors are caused by the breakdown of insulation, which may be caused by （）
A
penetration of moisture
B
accumulation of dirt
C
overheating
D
All of the above
参考答案
参考解析
解析：
暂无解析
更多 “单选题Electrical failures in motors are caused by the breakdown of insulation, which may be caused by （）A penetration of moistureB accumulation of dirtC overheatingD All of the above” 相关考题
考题
Diesel engine electric starting motors generally require heavier duty motors and motors and operate at higher voltages than comparable starting motors for gasoline engines due to _____________.A.higher speed requiredB.flywheel-effectC.lower starting temperaturesD.higher compression pressures
考题
What caused the blackout in July 1977?A. During a storm, lightning damaged cable.B. Because of unemployment.C. Heat waves had made people use too much electrical power.D. Because the looters damaged the electricity supply.
考题
Which two kinds of failures make the Data Recovery Advisor (DRA)generate a manual checklist? ()
A. failures because a data file is renamed by errorB. failures when no standby database is configuredC. failures that require no archive logs to be applied for recoveryD. failures due to loss of connectivity-for example, an unplugged disk cable
考题
If clearance between a piston and the cylinder wall is excessive, piston slap will occur. The slap itself is caused by_____.A.alternation of side thrustB.a breakdown of the lube oil film on the cylinderC.worn piston boss piston pin bearingsD.fluctuating gas pressure in tile combustion space
考题
Hydraulic machinery failures are commonly caused by contamination of the hydraulic fluid and ______.A.fluid frictionB.fluid turbulenceC.component misalignmentD.pressure surges
考题
An advantage of DC motors over AC motors is that they______.A.are less expensiveB.require less maintenanceC.can be started across the lineD.offer a more effective means of controlling speed
考题
Permanent magnetism is caused by ______.A.operation of electrical equipment and generators on board shipB.the earth's magnetic field affecting the ship's hard iron during constructionC.the horizontal component of the earth's magnetic field acting on the horizontal soft ironD.the vertical component of the earth's magnetic field acting on the vertical soft iron
考题
Loop guard and UniDirectional Link Detection both protect against Layer 2 STP loops. In which two ways does loop guard differ from UDLD in loop detection and prevention？（）A、Loop guard can be used with root guard simultaneously on the same port on the same VLAN while UDLD cannot.B、UDLD protects against STP failures caused by cabling problems that create one-way links.C、Loop guard detects and protects against duplicate packets being received and transmitted on different ports.D、UDLD protects against unidirectional cabling problems on copper and fiber media.E、Loop guard protects against STP failures caused by problems that result in the loss of BPDUs from a designated switch port.
考题
Which two kinds of failures make the Data Recovery Advisor (DRA)generate a manual checklist? （）A、failures because a data file is renamed by errorB、failures when no standby database is configuredC、failures that require no archive logs to be applied for recoveryD、failures due to loss of connectivity-for example, an unplugged disk cable
考题
Observe the following warning in an RMAN session of your database instance: WARNING: new failures were found since last LIST FAILURE command Which statement describes the scenario that must have produced this warning?（）A、The CHANGE FAILURE command has detected new failures recorded in the Automatic Diagnostic Repository(ADR)B、The VALIDATE DATABASE command has detected new failures recorded in the Automatic Diagnostic Repository (ADR)C、The ADVISE FAILURE command has detected new failures recorded in the Automatic Diagnostic Repository (ADR) since the last LIST FAILURED、The RECOVER command has detected new failures recorded in the Automatic Diagnostic Repository (ADR) since the last LIST FAILURE command was executed
考题
单选题When a rescuer finds an electrical burn victim in the vicinity of live electrical equipment or wiring，his first step is to（）.A
flush water over any burned area of the patientB
apply ointment to the burned areas on the patientC
get assistance to shut down electrical power in the areaD
remove the patient from the vicinity of the live electrical equipment or wiring
考题
多选题Loop guard and UniDirectional Link Detection both protect against Layer 2 STP loops. In which two ways does loop guard differ from UDLD in loop detection and prevention？ （）ALoop guard can be used with root guard simultaneously on the same port on the same VLAN while UDLD cannotBUDLD protects against STP failures caused by cabling problems that create one-way links.CLoop guard detects and protects against duplicate packets being received and transmitted on different portsDUDLD protects against unidirectional cabling problems on copper and fiber media.ELoop guard protects against STP failures caused by problems that result in the loss of BPDUs from a designated switch port.
考题
单选题Which of the following electric motors would be the safest and most reliable to use on the main deck of a vessel in foul weather conditions?（）A
Sealed motorsB
Drip proof motorsC
Enclosed motorsD
Watertight motors
考题
单选题Diesel engine electric starting motors generally require heavier duty motors and motors and operate at higher voltages than comparable starting motors for gasoline engines due to（）A
higher speed requiredB
flywheel-effectC
lower starting temperaturesD
higher compression pressures
考题
单选题An advantage of DC motors over AC motors is that they （）A
are less expensiveB
require less maintenanceC
can be started across the lineD
offer a more effective means of controlling speed
考题
单选题General, the best way for replacement of lamp is （）.A
after the point is reached at which the failures begin to increase rapidlyB
before the point is reached at which the failures begin to increase rapidlyC
before the point is reached at which the failures begin to increase slowlyD
after the point is reached at which the failures begin to increase slowly
考题
单选题The operator of electrical motors should keep a constant check on the loads they carry because （）A
low loads necessitate frequent insulation cleaningB
exceeding nameplate values shortens useful lifeC
energy is wasted if full loading is not utilizedD
power factor correction methods are load dependent
考题
单选题You executed the following commands in an RMAN session for your database instance that has failures: RMAN LIST FAILURE; After some time, you executed the following command in the same session: RMAN ADVISE FAILURE; But there are new failures recorded in the Automatic Diagnostic Repository (ADR) after the execution of the last LIST FAILURE command. Which statement is true for the above ADVISE FAILURE command in this scenario?（）A
It produces a warning for new failures before advising for CRITICAL and HIGH failures.B
It ignores new failures and considers the failures listed in the last LIST FAILURE command only.C
It produces an error with recommendation to run the LIST FAILURE command before the ADVISE FAILURE command.D
It produces advice only for new failures and the failures listed in the last LIST FAILURE command are ignored.
考题
单选题The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the（）.A
loss of residual magnetismB
absorption of moisture in the insulationC
insulation varnish flakingD
dirt collecting on the windings
考题
单选题Complete maintenance of electrical motors should include periodic checks for machine （）A
vibrationB
watertight integrityC
speed droopD
reactive power
考题
单选题Hydraulic machinery failures are commonly caused by contamination of the hydraulic fluid and （）.A
fluid frictionB
fluid turbulenceC
component misalignmentD
pressure surges
考题
单选题Permanent magnetism is caused by（）.A
operation of electrical equipment and generators on board shipB
the earth's magnetic field affecting the ship's hard iron during constructionC
the horizontal component of the earth's magnetic field acting on the horizontal soft ironD
the vertical component of the earth's magnetic field acting on the vertical soft iron
考题
单选题If clearance between a piston and the cylinder wall is excessive, piston slap will occurThe slap itself is caused by （）A
alternation of side thrustB
a breakdown of the lube oil film on the cylinder wallC
worn piston boss piston pin bearingsD
fluctuating gas pressure in the combustion space
考题
单选题The most common forms of main drive used on deck auxiliaries are （）.A
steam plants, electric motors and compressed airB
diesel engine, hydraulic machinery and compressed airC
steam plants, electric motors and hydraulic machineryD
diesel engines, steam plants and hydraulic machinery
考题
单选题Magnets are placed in horizontal trays in the compass binnacle to compensate for the（）.A
induced magnetism in the vessel's horizontal soft ironB
change in the magnetic field when the vessel inclines from verticalC
permanent magnetism of the vesselD
magnetic fields caused by electrical currents in the vicinity
考题
问答题什么是 device breakdown voltage？
热门标签
最新试卷