海船船员考试
单选题Prior to closing the breaker when paralleling two AC generators, the recommended practice is to have the frequency of the incoming machine （）A slightly less than the line frequencyB the same as the line frequencyC slightly greater than the line frequen
题目
slightly less than the line frequency
the same as the line frequency
slightly greater than the line frequency
All of the above
相似问题和答案
第1题：
A.Always stop the server prior to the backup
B.Stop the server or lock the tables prior to the backup
C.Stop the server or lock the databases prior to the backup
D.Make a copy of the .frm, .myd, and the .myi files
E.Make a copy of the binary log and tablespace files
第2题：
A circuit breaker and a fuse have a basic similarity(类似) in that they both ______.
A.can be reset to energize the circuit
B.should open the circuit when overloaded
C.will burn out when an over current flow develops
D.should short the circuit when overloaded
第3题：
The author quotes the example of our ancestors to show that education emerged __________.
[A] when people had enough time
[B] prior to better ways of finding food
[C] when people on longer went hung
[D] as a result of pressure on government
第4题：
When loading a tanker，you should ______．
A.load only one tank at a time
B.keep the seamen on watch on standby in the mess room
C.keep a strain on the loading hoses
D.close valves by closing them down，reopening one or two turns，and re-closing
第5题：
A circuit breaker and a fuse have a basic similarity in that they both______.
A.can be reset to energize the circuit
B.should open the circuit when overloaded
C.will burn out when an over current flow develops
D.should short the circuit when overloaded
第6题：
You are attempting to parallel two AC generators and the synchroscope pointer is revolving in the slow direction. This indicates that the frequency of the incoming machine is
A.higher than the bus frequency
B.lower than the bus frequency
C.file same as file bus frequency but out of phase with it
D.the same as the bus frequency, and the circuit breaker may be closed at nay pointer position
第7题：
While paralleling two AC generators using synchronizing lamps only, both lamps will go dark when the generators are______.
A.running at the same speed
B.grounded
C.of the same polarity
D.in phase
第8题：
A.higher than the bus equency
B.lower than the bus equency
C.the same as the bus frequency but out of phase with it
D.same as the bus frequency and the circuit breaker may be closed at
第9题：
When are fore and aft draft readings required to be entered in the unofficial logbook of a ship?
A.Once a day
B.Once a week
C.Prior to getting underway
D.Only when entering waters of different density
第10题：
Pollution regulations require that each scupper in an enclosed deck area have a ______．
A.Wooden plug
B.Soft rubber plug
C.Two-piece soft patch
D.Mechanical means of closing