【单选题】
无论采用的交一直一交变频器是电压型还是电流型，控制部分在结构上均由___三部分组成。
A. 电压控制、频率控制以及两者协调控制
B. 电压控制、电流控制以及两者协调控制
C. 电压控制、频率控制以及电流控制
D. 电流控制、频率控制以及两者协调控制
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相关试题
【单选题】
变频电动机与通用感应电动机相比其特点是___。
A. 低频工作时，电动机的损耗小
B. 低频工作时电动机的损耗大
C. 频率范围大
D. 效率高
【单选题】
根据生产机械调速特性要求的不同，可采用不同的变频调速系统。采用___的变频调速系统技术性能最优。
A. 开环恒压频比控制
B. 无测速矢量控制
C. 有测速矢量控制
D. 直接转矩控制
【单选题】
脉冲分配器的功能有___。
A. 输出时钟CK和方向指令DIR
B. 输出功率开关所需的驱动信号
C. 产生各相通断的时序逻辑信号
D. 电流反馈控制及保护电路
【单选题】
直流调速系统中直流电动机的励磁供电大多采用___,加电容进波电路。
A. 专用高性能稳压电路
B. 三相桥式整流电路
C. 单相桥式整流电路
D. 三相可控整流电路
【单选题】
目前工业控制领域直流调速系统中主要采用___
A. 直流斩波器调压
B. 旋转变流机组调压
C. 电枢国路非电阻R调压
D. 静止可整整流器词压
【单选题】
___是直流调速系统的主要控制方案。
A. 改变电源频率
B. 调节电枢电压
C. 改变电枢回路电阻R
D. 改变转类菜
【单选题】
调节直流电动机电枢电压可获得___性能。
A. 恒功率调速
B. 恒转矩调速
C. 弱磁通调速
D. 强磁通调速
【单选题】
___是直流调速系统的主要调速方案。
A. 减弱励磁磁通
B. 调节电枢电压
C. 改变电枢回路电阻R
D. 增强励磁激通
【单选题】
测速发电机的灵敏度高，对调速系统性能的影响是___。
A. 没有影响
B. 有影响，灵敏度越高越好
C. 有影响，灵敏度越低越好
D. 对系统的稳态性能没有影响，但对动态性能有影响
【单选题】
速度检测与反馈电路的精度，对调速系统的影响是___。
A. 决定系统稳态精度
B. 决定速度反馈系数
C. 只影响系统动态性能
D. 不影响，系统可自我调节
【单选题】
工程设计中的调速精度指标要求在所有调速特性上都能满足，故应是调速系统___特性的静差率。
A. 最高调速
B. 额定转速
C. 平均转速
D. 最低转速
【单选题】
___就是在原有的系统中，有目的地增添一些装置(或元件)，人为地改变系统的结构和参数，使系统的性能获得改善，以满足所要求的稳定性指标。
A. 系统校正
B. 反馈校正
C. 顺馈补偿
D. 串联校正
【单选题】
闭环控制系统具有反馈环节，它将依靠___进行自动调节，已补偿扰动对系统产生的影响。
A. 正反馈环节
B. 负反馈环节
C. 校正装置
D. 补偿环节
【单选题】
直流V—M调速系统较PWM调速系统的主要优点是___。
A. 动态响应快
B. 自动化程度高
C. 控制性能好
D. 大功率时性价比高
【单选题】
在带PI调节器的无静差直流调速系统中，可以用___来抑制突加给定电压时的电流冲击，以保证系统有较大的比例系数来满足稳态性能指标要求。
A. 电流截止正反馈
B. 电流截止负反馈
C. 电流正反馈补偿
D. 电流负反馈
【单选题】
当系统的机械特性硬度一定时，如要求的静差率。越小，则调速范围D___。
A. 越大
B. 越小
C. 可大可小
D. 不变
【单选题】
调速系统的调速范围和静差率这两个指标___。
A. 相互平等
B. 互不相关
C. 相互制约
D. 相互补充
【单选题】
与通用型异步电动机相比变频调速专用电动机的特点是___。
A. 外加变频电源风扇实行强制通风散热；加大电磁负荷的裕量；加强绝缘
B. U/f控制时磁路容易饱和；加强绝缘；外加电源变频风扇实行强制通风
C. 外加电源变频风扇实行强制通风；加大电磁负荷的裕量；加强绝缘
D. 外加工频电源风扇实行强制通风；加大电磁负荷的裕量；加强绝缘
【单选题】
测速发电机的用途广泛，可作为___。
A. 检测速度的元件，微分、积分元件
B. 微分、积分元件，功率放大元件
C. 加速或延迟信号，执行元件
D. 检查速度的元件，执行元件
【单选题】
控制系统对直流测速发电机的要求有___。
A. 输出电压与转速成线性关系，正反转特性一致
B. 输出灵敏度低，输出电压纹波小
C. 发电机的惯性大，输出灵敏度高
D. 输出电压与转速成线性关系，发电机的惯性大
【单选题】
国产CYD系列高灵敏直流测速发电机，具有结构简单、耦合度好、___、反应快、可靠性好的特点。
A. 输出比电势低，线性误差小
B. 输出比电势高，线性误差小
C. 输出比电势高，线性误差大
D. 输出比电势低，线性误差大
【单选题】
___直流测速发电机受温度变化的影响较小，输出变化小，斜率高，线性误差小，应用最多。
A. 电磁式
B. 他励式
C. 永磁式
D. 霍尔无刷式
【单选题】
直流测速发电机在___时，由于电枢电流的去磁作用，使输出电压下降，从而破坏了输出特性U=f(n)的线性关系。
A. RL较小或转速过高
B. RL较大或转速过高
C. RL较小或转速过低
D. 转速过低
【单选题】
为减小剩余电压误差，其办法有___。
A. 提高励磁电源频率，在输出绕组电路补偿
B. 降低励磁电源频率，提高制造精度和加工精度
C. 提高制造精度和加工精度，在输入绕组电路补偿
D. 提高制造精度和加工精度，在输出绕组电路补偿
【单选题】
为了减小直流测速发电机的误差，使用时必须注意___。
A. 外接负载电阻尽可能大些
B. 外接负载电阻尽可能小些
C. 外接负载电阻等于规定的最小负载电阻
D. 在直流测速发电机输出端连接滤波电路
【单选题】
实际中，CYD系列永磁式低速直流测速发电机的线性误差为___。
A. 1%~5%
B. 0.5%~1%
C. 0.1%~0.25%
D. 0.01%~0.1%
【单选题】
实际的直流测速发电机一定存在某种程度的非线性误差，CYD系列永磁式低速直流测速发电机的线性误差为___。
A. 19%一2%
B. 0.5%-1%
C. 0.1%-0.25%
D. 0.01%-0.1%
【单选题】
测速发电机产生误差的原因很多，主要有___，电刷与换向器的接触电阻和接触电压，换向纹波，火花和电磁干扰等。
A. 电枢反应，电枢电阻
B. 电枢电阻
C. 电枢反应，延迟换向
D. 换向纹波，机械联轴器松动
【单选题】
直流调速装置安装无线电干扰抑制滤被器与进线电抗器，必须遵守滤被器网侧电缆与负载侧电缆在空间上必须隔离。整流器交流侧电抗器电流按___。
A. 电动机电枢额定电流选取
B. 等于电动机电枢额定电流0.82倍选取
C. 等于直流侧电流选取
D. 等于直流侧电流0.82倍选取
【单选题】
直流调速装置可运用于不同的环境中，并且使用的电气元件在抗干扰性能与干扰辐射强度存在较大差别，所以安装应以实际情况为基础，遵守___规则。
A. 3C认证
B. 安全
C. EMC
D. 企业规范
【单选题】
直流调速装置调试的原则一般是___。
A. 先检查，后调试
B. 先调试，后检查
C. 先系统调试，后单机调试
D. 边检查边调试线性
【单选题】
直流调速装置通电前硬件检查内容有电源电路检查，信号线、控制线检查，设备接线检查，PLC接地检查。通电前一定要认真进行___，以防止通电后引起设备损坏。
A. 电源电路检查
B. 信号线、控制线检查
C. 设备接线检查
D. PLC接地检查
【单选题】
直流调速装置安装的现场调试主要有硬件检查和程序(软件)调试两大内容。调试前准备工作主要有：收集有关资料、熟悉并阅读有关资料和说明书、主设备调试用仪表的准备。其中要___，这是日后正确使用设备的基础。
A. 程序(教件)调试
B. 熟悉并阅读有关资料和说明书
C. 设备接线检查
D. 硬件检查
【单选题】
直流调速装置调试前的准备工作主要有___。
A. 收集有关资料，熟悉并阅读有关资料和说明，调试用仪表的准备
B. 收集有关资料，接通电源
C. 阅读有关资料和说明书，加装漏电保护器
D. 调试用仪表的准备，主电路和控制电路的接线，编制和输入控制程序
【单选题】
双闭环直流调速系统调试中，出现转速给定值U，达到设定最大值时，而转速还未达到要求值，应___。
A. 逐步减小速度负反馈信号
B. 调整速度调节器ASR限幅1s
C. 调整电流调书器ACR限幅
D. 逐步减小电流负反馈信号
【单选题】
欧陆514直流调速装置ASR的限幅值是用电位器P5来调整的。通过端子7上监式低外接0-7.5V的直流电压，调节P5可得到最大电枢电流为___。
A. 1.1格标定电流的限幅值
B. 1.5倍标定电流的限幅值1%
C. 1.1格电机额定电流的限幅值
D. 等于电机额定电流的限幅值独电阻
【单选题】
欧陆514直流调速装置是___直流可逆调速系统。
A. 逻辑无环流
B. 可控环流
C. 逻根选触无环流
D. α=β配合控制有环流。
【单选题】
空心杯转子异步测速发电机主要由内定子，外定子及杯形转子所组成。以下正确的说法是___。
A. 励磁绕组，输出绕组分别嵌在外/内定子上，彼此在空间相差90°电角度
B. 励磁绕组，输出绕组分别嵌在内/外定子上，彼此在空间相差90°电角度
C. 励磁绕组，输出绕组嵌在内定子上，彼此在空间相差180°电角度
D. 励磁绕组，输出绕组嵌在外定子上，彼此在空间相差90°电角度
【单选题】
异步测速发电机的空心杯转子是用___材料做成的。
A. 低电阻
B. 高电阻
C. 低导磁
D. 高导磁
【单选题】
交流测速发电机有空心杯转子异步测速发电机、笼型转子异步测速发电机和同步测速发电机3种，目前应用最为广泛的是___。
A. 同步测速发电机
B. 笼型转子异步测速发电机
C. 空心杯转子异步测速发电机
D. 同步测速发电机和笼型转子异步测速发电机
推荐试题
【多选题】
What two enhancements are in VMFS6 but not in VMFS5? (Choose two.)___
A. Support for 4k native disks
B. Support for 512e disks
C. GPT storage device partitioning
D. Automatic space reclamation
【多选题】
Which two statements describe why a vSphere DRS cluster would report load imbalance? (Choose two.)___
A. The configured migration threshold is too high.
B. The configured migration threshold is too low.
C. DRS is configured for Partially Automated.
D. Enhanced vMotion Compatibility (EVC) is enabled.
【多选题】
A vSphere Administrator must ensure that vCenter Server service is running in a domain user account rather than Local System Account. To accomplish this, the user account should have which two permissions? (Choose two.)___
A. Log on as a service.
B. Act as part of the operating system.
C. Log on as a batch job.
D. Log on locally.
【多选题】
A virtual machine fails to power on after being deployed from a template. What two remediation steps could correct this issue? (Choose two.)___
A. Increase CPU reservation
B. Decrease memory reservation
C. Increase memory reservation
D. Increase datastore capacity
E. Decrease CPU reservation
【多选题】
Which three directories are available under the vcsa-cli-installer folder of the vCenter Server Appliance installation media? (Choose three.)___
A. \mac
B. \ovftool
C. \migration-assistant
D. \win32
E. \lin64
【多选题】
What are three considerations when booting ESXihost from SAN software FCoE? (Choose three.)___
A. The VMware_FCoE_vSwitch that the installer automatically created cannot be changed.
B. Boot LUN cannot be shared with other hosts even on shared storage.
C. Multipathing is not supported at pre-boot.
D. Software FCoE boot configuration cannot be changed from within
E. SXi.
【多选题】
Which two choices are applicable to vSphere Availability? (Choose two.)___
A. Heartbeat Datastores
B. VM Startup/Shutdoown
C. Power Management
D. Admission Control
【多选题】
A user is a member of groups A and B. -VM10 and VM20 are in VM Folder. -Group A is assigned permission “Read-only” on VM Folder. What two configurations will allow the user to edit the settings for only VM10? (Choose two.)___
A. Assign group B permission “virtual machine power user” to VM10.
B. Assign group B permission “virtual machine console user” to VM10.
C. Assign group A permission “virtual machine console user” to VM10.
D. Assign group A permission “virtual machine power user” to VM10.
【多选题】
Which two new vSphere 6.5 features enable an Administrator to locate configuration options when creating or editing host profiles more easily than in previous versions? (Choose two.)___
A. Add the configuration option to favorites.
B. Navigate the option tree.
C. Search for the configuration option.
D. Copy the configuration option from a different profile.
【多选题】
What are the two valid storage controller types for VMs on ESXi 6.5? (Choose two.)___
A. FCoE
B. SATA
C. NVMe
D. iSCSI
【多选题】
Which two options can optimize conversion with VMware Converter? (Choose two.)___
A. Disable real-time antivirus scanners.
B. Remove the source from Active Directory.
C. Remove third-party device drivers.
D. Exclude diagnostic partitions from conversion.
E. Disable Volume Shadow Copy (VSS).
【多选题】
vSphere Availability considers which two factors for virtual machine restarts? (Choose two.)___
A. Host Isolation Response
B. file accessibility
C. NUMA node size
D. resource reservations
【多选题】
Which two virtual NICs support Wake-on-Lan to resume a virtual machine that is in standby mode? (Choose two)___
A. Flexible
B. E1000E
C. E1000
D. vmxnet 3
【多选题】
Which two logs should be examined to troubleshoot a Windows vCenter Server upgrade failure? (Choose two.)___
A. vminst.log
B. vim-um-msi.log
C. firstboot.log
D. pkgmgr.log
【多选题】
Which are two supported storage primitives for VAAI NAS? (Choose two.)___
A. Full File Clone
B. Reserve Space
C. hardware assisted locking
D. block zeroing
【多选题】
Which two parameters must be configured for Windows in-guest disk mirroring? (Choose two.)___
A. scsi#.returnNoConnectDuringAPD = “FALSE”
B. scsi#.terminateVMOnPDL = “TRUE”
C. scsi#.returnBusyOnNoConnectStatus = “FALSE”
D. scsi#.returnNoConnectDuringAPD = “TRUE”
【多选题】
Which two items are required to enable NPIV in a virtual machine? (Choose two.)___
A. use of physical RDMs
B. physical HBA support
C. use of virtual disks
D. hardware version 11 or higher
【多选题】
A vSphere Administrator has VM Component Protection (VMCP) enabled, but the VM was not restarted when one of the VMFS datastores experienced an All Paths Down (APD) failure. What two scenarios would explain why the virtual machine was not restarted? (Choose two.)___
A. VM Monitoring is required in order for VMCP to failover during an APD event.
B. VMware Tools is not installed on the guest operating system for the VM.
C. Insufficient Capacity is available on the failover ESXi hosts.
D. The APD failure was corrected before the VM could be restarted.
【多选题】
What are two requirements in order to restore a Resource Pool Tree from a snapshot? (Choose two.)___
A. vSphere DRS must be turned on.
B. A restore can only be performed on a vSphere DRS cluster within the original vCenter Server.
C. vSphere
D. RS must be turned off.
【多选题】
Which three vSphere features are compatible with vSphere Replication? (Choose three.)___
A. vSphere High Availability
B. vSphere Fault Tolerance
C. vSphere Storage
D. RS
【多选题】
What two VMware Remote Console Options can be defined in the virtual machine settings? (Choose two.)___
A. Boot Delay
B. Maximum number of sessions
C. Guest OS lock
D. Total video memory
【多选题】
VMware Converter can import a powered off virtual machine from which two virtual machine platforms?(Choose two.)___
A. Microsoft Hyper-V
B. Citrix Xen
C. VMware Workstation
D. Linux with KVM
【多选题】
Which two options allow storage space reclamation? (Choose two.)___
A. Use VMFS6 datastores.
B. Use esxcli storage vmfs unmap.
C. Use the SAN console (management tool).
D. Use the vSphere Web Client.
【多选题】
An administrator must reprovision 25 hosts with a new image profile that he has created. Which two methods can the administrator use to change the image profile? (Choose two.)___
A. From the vSphere Web client home page, select the Deploy Rules tab in the Auto Deploy section.
B. Run the Copy-Deploy Rule and specify the Replace Item parameter with Power CLI.
C. From the vSphere Web client home page, select the Assign Rules tab in the Auto
D. eploy section.
【多选题】
What are three parameters for traffic filtering or marking? (Choose three.)___
A. Protocol
B. Traffic Direction
C. DSCP value
D. virtual Port ID
【多选题】
The vSphere administrator must change the path selection policy (PSP) to comply with best practices. Which two interfaces can be used to change the PSP? (Choose two.)___
A. ESXi shell
B. vSphere Client
C. ESXi host client
D. vSphere Web Client
【多选题】
In what two ways can Storage DRS load balance virtual machines? (Choose two.)___
A. anti-affinity rules
B. virtual storage controller
C. guest OS family
D. I/O latency
【多选题】
What two reasons can explain why a host cannot be removed from a vSphere Distributed Switch? (Choose two.)___
A. There are virtual machine network adapters connected to the switch.
B. There are blocked ports on the switch.
C. There are LACP LAGs configured on the switch.
D. There are VMkernel network adapters connected to the switch.
【多选题】
Which three requirements are true for the vCenter Server HA network? (Choose three.)___
A. Network latency between all nodes must be less than 10 milliseconds.
B. IP addresses for all nodes must be static.
C. HA network IP addresses for all nodes can be on different subnets.
D. IP addresses must be on the same network as the management network.
E. A default gateway must be configured.
【多选题】
Which two statements correctly describe Normal Lockdown Mode? (Choose two.)___
A. ESXi Shell and SSH services are independent of lockdown mode.
B. In normal lockdown mode the DCUI service is stopped.
C. ESXi Shell and SSH services are dependent of lockdown mode and cannot be configured.
D. In normal lockdown mode the DCUI service is running.
【多选题】
The Health check feature in the vSphere Distributed Switch helps troubleshoot network connectivity. What three checks does this feature perform? (Choose three.)___
A. Network Utilization
B. MTU
C. Teaming and Failover
D. VLAN
【多选题】
What are the three types of nodes in a vCenterServer HA cluster? (Choose three.)___
A. Master
B. Replica
C. Witness
D. Active
E. Passive
【多选题】
What are two consequences of turning off vSphere DRS on a cluster? (Choose two.)___
A. vMotion capability will be lost.
B. Resource pools will be lost.
C. vApps will be lost.
D. Affinity rules will be lost.
【多选题】
Which two protocols can be used to back up vCenter Server Appliance Instance? (Choose two.)___
A. iSCSI
B. HTTPS
C. FTP
D. NFS
【多选题】
What are two requirements to enable EVC in a vSphere DRS cluster? (Choose two.)___
A. CPU must be in the same family and of the same speed.
B. CPUs must be from the same vendor.
C. EVC must use the lowest possible baseline supported by the hardware.
D. No VMs may be running in the cluster.
【多选题】
In Advanced settings on a vSphere host, Security.Password Quality Control set as retry=3 min=disabled, disabled, disabled, 7, 7 . Which two passwords are valid? (Choose two.)___
A. xQaT3#A
B. P@ssw0rd
C. xQaTEh2
D. Xqat3h!
E. xQaTEhb!
【多选题】
To support Auto-Deploy, which two network requirements must be met? (Choose two.)___
A. IP multicast support
B. IPv4 or IPv6
C. PXE boot
D. 10 GbE networking
【多选题】
A vSphere administrator receives reports of a virtual machine performing extremely slowly, with CPU usage being the suspected bottleneck. After reviewing esxtop (view the Exhibit), which two scenarios could cause a performance problem for the virtual machine? (Choose two.)___
A. A processor affinity is configured for the virtual machine.
B. A virtual machine CPU limit is configured.
C. A virtual machine reservation is configured.
D. A virtual machine memory limit is configured.
E. A virtual machine CPU reservation is configured.
【多选题】
Which three source object types are available for subscription when creating a subscribed content library in vSphere 6.5? (Choose three.)___
A. vSphere 6 library
B. HTTP server
C. vCD 5.5 catalog
D. CIFS repository
E. 3rd-party library
【多选题】
药学服务的主要实施内容正确的是___
A. 医、药、护有机结合，共同承担医疗责任
B. 药学服务只是针对患者个人
C. 协助医护人员制定和实施药物治疗方案
D. 定期对药物的使用和管理进行科学评估
E. 主要是积极参与疾病的治疗，预防和保健则与药学服务关系不大
