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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
参考答案
更多 “ A circuit breaker and a fuse have a basic similarity(类似) in that they both ______.A.can be reset to energize the circuitB.should open the circuit when overloadedC.will burn out when an over current flow developsD.should short the circuit when overloaded ” 相关考题
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When voltage and current developed in an AC circuit reach their peak values at the same time, the power factor is _____.A.laggingB.leadingC.maximumD.minimum
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For (71) service, we need a virtual-circuit subnet. Let us see how that works. The idea behind virtual circuits is to avoid having to choose a new (72) for every packet sent. Instead, when a connection is established, a route from the (73)machine to the destination machine is chosen as part of the connection setup and stored in tables inside the (74) That route is used for all traffic flowing over the connection, exactly the same way that the telephone system works. When the connection is released, the virtual circuit is also terminated. With connection-oriented service, each packet carries an (75) telling which virtual circuit it belongs to.A．connectionlessB．connection-orientedC．datagramD．telegram
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On an ONS 15454 node you can tunnel an ().
A. SDH circuit over a SONET network delivering it as an SDH signalB. SDH circuit over a SONET network delivering it as a SONET signalC. SONET circuit over an SDH network delivering it as an SDH signalD. SONET circuit over an SDH network delivering it as a SONET signal
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A circuit breaker and a fuse have a basic similarity in that they both______.A.can be reset to energize the circuitB.should open the circuit when overloadedC.will burn out when an over current flow developsD.should short the circuit when overloaded
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A circuit breaker differs from a fuse in that a circuit breaker ______.A.melts and must be replacedB.is enclosed in a tube of insulating material with metal ferrules(环) at each endC.gives no visual indication of having opened the circuitD.trips to break the circuit and may be reset
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If an attempt is made to hoist a load that exceeds the capacity of an electric winch，an overload safety device causes a circuit breaker to cut off the current to the winch motor ______．A.when the line pull reaches the rated winch capacityB.after the line pull exceeds the rated winch capacityC.after a short build-up of torqueD.immediately
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Running an electric winch at slow speed over a long period of time causes ______．A.the speed to be retarded by the friction brakeB.a load to go downward at full speedC.the circuit breaker to turn offD.the resistors to overheat and eventually burn out
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On an ONS 15454 node you can tunnel a（n） （）.A、 SDH circuit over a SONET network delivering it as an SDH signalB、 SDH circuit over a SONET network delivering it as a SONET signalC、 SONET circuit over an SDH network delivering it as an SDH signalD、 SONET circuit over an SDH network delivering it as a SONET signal
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For (1) service, we need a virtual-circuit subnet. Let us see how that works. The idea behind virtual circuits is to avoid having to choose a new (2) for every packet sent. Instead,when a connection is established, a route from the(3) machine to the destination machine is chosen as part of the connection setup and stored in tables inside the (4) . That route is used for all traffic flowing over the connection, exactly the same way that the telephone system works.When the connection is released, the virtual circuit is also terminated. With connection-oriented service, each packet carries an (5) telling which virtual circuit it belongs to.
空白（5）处应选择（）A、addressB、identifierC、interfaceD、element
考题
On an ONS 15454 node you can tunnel an （）.A、SDH circuit over a SONET network delivering it as an SDH signalB、SDH circuit over a SONET network delivering it as a SONET signalC、SONET circuit over an SDH network delivering it as an SDH signalD、SONET circuit over an SDH network delivering it as a SONET signal
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单选题When the voltage remains constant and the resistance is increased in a series circuit, the flow of current （）A
increases by the square of the original valueB
increasesC
remains the sameD
decreases
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单选题If an attempt is made to hoist a load that exceeds the capacity of an electric winch，an overload safety device causes a circuit breaker to cut off the current to the winch motor（）.A
when the line pull reaches the rated winch capacityB
after the line pull exceeds the rated winch capacityC
after a short build-up of torqueD
immediately
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单选题In a simple series circuit, the entire source voltage will drop across （）A
the resistor next to the negative terminalB
a short circuitC
the resistor next to the positive terminalD
an open circuit
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单选题A circuit breaker differs from a fuse in that a circuit breaker （）.A
melts and must be replacedB
is enclosed in a tube of insulating material with metal ferrules at each endC
gives no visual indication of having opened the circuitD
trips to break the circuit and may be reset
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单选题A circuit breaker and a fuse have a basic similarity in that they both （）.A
can be reset to energize the circuitB
should open the circuit when overloadedC
will burn out when an over current flow developsD
All of the above
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单选题If the resistance of a circuit is cut in half and the applied voltage is kept constant, the current flow will be （）.A
doubledB
quadrupledC
unchangedD
cut in half
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单选题When voltage and current developed in an AC circuit reach their peak values at the same time, the power factor is （）A
laggingB
leadingC
maximumD
minimum
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单选题When securing an AC generator, you should FIRST （）.A
open the generator circuit breakerB
switch the voltage regulator to “manual”C
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prevent alternator motorizationD
prevent low voltage tripout
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单选题Which of the listed precautions should be taken when cleaning the internals of a motor with compressed air?（）A
Open the machine on both ends so as to allow the air and dust to escapeB
Be certain that the circuit breaker is opened and tagged on the feeder panelC
Be certain that the air is clean and as dry as possibleD
All of the above
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单选题Fuses placed in series with a thermal trip-type circuit breaker are used for （）.A
time-delay protectionB
short-circuit protectionC
short duration surge protectionD
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单选题Before any work on electrical or electronic equipment is performed, which of the following precautions should be carried out （）A
De-energize the applicable switchboard busB
Bypass the interlocksC
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Station a man at the circuit supply switch
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单选题Inductance is the property of an electric circuit that （）A
opposes any change in the applied voltageB
opposes any change in the current flow through the circuitC
aids any changes in the applied voltageD
aids any changes in the current through the circuit
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单选题When two different metals are joined to form a closed circuit and exposed to different temperatures at their junctions （） which can be used to measure temperature.A
a current will flowB
a power will developC
a heat will flowD
a pressure will produce
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单选题When working on a high voltage circuit, you should always have another person present with you.This person should have a good working knowledge of （）A
the circuit being worked on and the location of all switches and circuit breakers controlling itB
first-aid techniques for treating electrical shockC
cardiopulmonary resuscitation (CPR)D
All of the above
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单选题A transformer in an electric circuit serves to （）A
generate its own electrical powerB
transform electrical energy into mechanical energyC
increase or decrease circuit voltage as requiredD
convert AC current to DC current
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