【判断题】
时间继电器有电磁式、电动式、空气式和电子式
A. 对
B. 错
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A
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【判断题】
热继电器主要用于电动机的过流保护
A. 对
B. 错
【判断题】
使用热继电器时应将热驱动器件的电阻丝并联在电动机的主电路中
A. 对
B. 错
【判断题】
热继电器动作时间与通过电流的关系为定时限特性,即通过电流愈大,动作时间愈快
A. 对
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【判断题】
继电器与接触器工作原理基本相同,主要区别是触头系统不同,故应用也不同
A. 对
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【判断题】
中间继电器只能作转换控制信号的中间元件使用,不能用来直接通断电路
A. 对
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【判断题】
热继电器的保护动作在过载后需要经过一段时间后才能执行
A. 对
B. 错
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客车用荧光灯逆变器可将车内48V直流电变换为220V,50Hz的交流电,供荧光灯使用
A. 对
B. 错
【判断题】
BY-2型逆变器负载回路采用LC串联谐振电路,提高逆变器效率达85%
A. 对
B. 错
【判断题】
BY-2型逆变器自保护装置的主要控制元件是晶闸管
A. 对
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目前客车空调机组温度控制器广泛采用电子式温度控制器
A. 对
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【判断题】
98型应急电源整流器输入电源电压为220V,50Hz
A. 对
B. 错
【判断题】
空调客车上使用的免维护密封铅酸电池,运用中不需要补充水或酸
A. 对
B. 错
【判断题】
正常运行的免维护密密封铅酸电池,不需定期检查在充放电时各节的温度情况
A. 对
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【判断题】
运用中的免维护密封铅酸电池,不需检查电解液浓度
A. 对
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【判断题】
熔断器熔管的作用只是作为保护熔体用
A. 对
B. 错
【判断题】
时间继电器有通电延时与断电延时两种类型
A. 对
B. 错
【判断题】
接触器除通断电路外,还具备短路和过载保护作用
A. 对
B. 错
【判断题】
热继电器的热元件的额定电流一般按电动机的额定电流选取
A. 对
B. 错
【判断题】
0.5kW以下的直流电动机可采用全压直流启动
A. 对
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【判断题】
三相异步电动机运行时转子突然卡住不动,不及时切断电源电动机也不会烧坏
A. 对
B. 错
【判断题】
电动机启动时发出嗡嗡声,是由于电动机缺相运转以致电流过大而引起的
A. 对
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晶体管逆变器主振荡电路是利用三极管的开关特性作为直流断续器的
A. 对
B. 错
【判断题】
振荡器是正反馈电路
A. 对
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【判断题】
铅蓄电池在放电过程中,内阻逐渐增加;充电过程中,内阻逐渐减小
A. 对
B. 错
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铅蓄电池放电时,负极板铅释放电子,在电解液作用下变为硫酸铅
A. 对
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镉镍蓄电池电解液应尽量避免与空气接触,以防生成危害电池的杂质
A. 对
B. 错
【判断题】
镉镍蓄电池使用苛性碱作电解液,苛性碱对人体皮肤和眼睛没有损害
A. 对
B. 错
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镉镍蓄电池泄气装置中的密封橡胶圈漏气,蓄电池可照常使用
A. 对
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镉镍蓄电池不能过放电,以免氧气和氢气析出,冲开橡胶圈泄出气体
A. 对
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使用500V兆欧表测量客车配线,易损坏车电装置中的半导体元件
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变压器温度的测量主要是通过对其油温的测量来实现的,如果发现油温较平时相同负载和相同条件下高出10℃时,应考虑变压器内发生了故障
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J5型感应子发电机为E级绝缘
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J5型感应子发电机输出的交流电压经整流后,供负载和蓄电池充电用,充电电流由限流节控制为35A
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KP-2A型控制箱中发电机过压保护电路整定值为63V
A. 对
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KP-2A型控制箱过压保护电路的主要元件是稳压管CW2
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KP-2A型控制箱的主要控制元件为晶体三极管
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KP-2A型控制箱的主整流电路采用晶闸管三相可控整流电路
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客车电扇在额定电压下,连续运转1h,电枢绕组及励磁绕组的温升不得超过50℃
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客车电扇电机绕组的绝缘电阻在温升后测量,其值应在1M以上
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Which statements about the native VLAN is true ?___
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When you edit an IPS subsignature, what is the effect on the parent signature and the family of subsignatures?___
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Which type of firewall can perform deep packet inspection?___
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You have implemented a dynamic blacklist, using security intelligence to block illicit network activity. However, the blacklist contains several approved connections that users must access for usiness pur poses. Which action can you take to retain the blacklist while allowing users to access the approve d sites?___
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When connecting to an external resource,you must change a source IP address to use one IP address from a range of 207.165.201.1 to 207.165.1.30. Which option do you implement ?___
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【单选题】
Refer to the exhibit. 【nat(ins,any)dynamic interface】Which ty pe of NaT is configured on a Cisco ASA?___
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B. source identity NAT
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【单选题】
Which mitigation technology for web-based threats prevents the removal of confidential data from the network?___
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【单选题】
Refer to the exhibit. What is the effect of the given configuration?___
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【多选题】
What are two major considerations when choosing between a SPAN and a TAP when plementing IPS?___
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【多选题】
What are two direct-to-tower methods for redirecting web traffic to Cisco Cloud Web Security?___
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【多选题】
Which three descriptions of RADIUS are true? ___
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【多选题】
Which two configurations can prevent VLAN hopping attack from attackers at VLAN 10?___
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D. applying ACl between VLAN
E. using switchport mode access command on all host ports
F. using switchport nonegotiate command on dynamic desirable ports
【多选题】
What are two features of transparent firewall mode ___
A. It conceals the presence of the firewall from attackers
B. It allows some traffic that is blocked in routed mode
C. It enables the aSA to perform as a router.
D. It acts as a routed hop in the network.
E. It is configured by default
【多选题】
Which two models of A sa tend to be used in a data center?___
A. 5555X
B. 5585X
C. ASA service module
D. 5512X
E. 5540
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【多选题】
Which two statements about hardware-based encrption are true?___
A. It is widely accessible
B. It is potentially easier to compromise than software-based encryption. It requires minimal configuration
C. It requires minimal configuration
D. It can be implemented without impacting performance
E. It is highly cost-effective
【多选题】
In which two modes can the Cisco We b Security appliance be de ployed?___
A. as a transparent proxy using the Secure Sockets Layer protocol
B. as a transparent proxy using the Web Cache Communication Protocol
C. explicit proxy mode
D. as a transparent proxy using the Hyper Text Transfer Protocol
E. explicit active mode
【单选题】
1.三相刀开关的图形符号与交流接触器的主触点符号是___。
A. 一样的
B. 可以互换
C. 有区别的
D. 没有区别