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1、机电控制均可结程序控制器技术试题一、简答题1.电磁离合器有哪几种，各自利于什么原理而制成?答：电磁离合器有摩擦片式离合器、电磁粉末离合器、电磁转差离合器等。摩擦片式离合器和电磁粉末离合器是利用摩擦原理制成的，电磁转差离合器是利用电磁感应原理制成的。2.机电设备电器控制线路的表示方法有几种?各有何用途?答：电器控制线路的表示方法有:电气原理图、电气设备安装图和电气设备接线图。电气原理图用来表示电器控制线路的工作原理、以及各电气元件的作用和相互关系。电气设备安装图用来表示各种电器在生产设备和电器控制柜中的实际安装位置。电气设备接线图用来表示各电气元件之间实际接线情况，它为电气元件的配线、检修和施工
2、提供了方便，实际工作时与电气原理图配合使用。3.在选择机电设备拖动用的电动机时，若选用绕线式异步电动机是出于什么考虑?答：对于要求经常起、制动，且负载转距较大、又有一定调速要求的机电设备，应考虑选用绕线式异步电动机;对于周期性波动负载的生产设备，为了削平尖峰负载，一般都采用电动机带飞轮工作，这种情况下也应选用绕线式异步电动机。4.PLC基本硬件由哪几部分组成?答：PLC是由CPU单元，数据存储器、寄存器(系统软件和用户程序寄存器)，输入、输出接口单元，按制程序，电源，计算机和编程软件或编程器组成。5.什么叫扫描工作方式?什么叫扫描周期? 答：CPU从第一条指令开始，顺序逐条地执行用户程序，直到
3、用户程序结束。然后返回第一条指令开始新的一轮扫描。PLC就是这样周而复始地重复上述的工作方式称为扫描工作方式。扫描一次所用的时间称为扫描周期。2电器控制线路的设计要遵循的基本原则是什么？答：应最大限度地满足机电设备对电器控制线路的要求；在满足生产要求的前提下，力求控制线路简单、布局合理、电气元件选择正确并得到充分利用；保证控制线路的安全可靠；便于操作和维修。3. PLC 主要特点有哪些？PLC的发展趋势如何？答：可靠性高，通用性强，使用灵活、方便，编程简单。PLC的发展有两个主要趋势。其一是向体积更小、速度更快、可靠性高、功能更强、价格更低的小型PLC方向发展；其二是向功能大型化、网络化、良好
4、兼容性和多功能方向发展。1.电动机起动电流很大，起动时热继电器会不会动作？为什么？答：起动时热继电器不会动作，这是因为热继电器是按照热效应原理来工作的，具有热惯性，作用时间短的大电流不会使它动作。2.自锁环节怎样组成？它起什么作用？并具有什么功能？答：一般可用起动按钮和接触器的常开触点并联，然后再和接触器的线圈串联可得。当按下起动按钮后，可实现长动，它又具有失压保护功能。3.CPMIA PLC的内部继电器是怎样划分的？哪些继电器有断电保护功能？答：内部继电器区分为两部分：一部分供输入点/输出点用，称为输入/输出继电器区；另一部分供PLC内部的程序使用，称为内部辅助继电器区。输入继电器区有10个
5、通道000009，其中000，001通道是CPU单元输入通道，002009通道用于和CPU单元连接的扩展单元的输入通道。输出继电器区有10个通道010019，其中010，011通道用于CPU单元输出通道，012019通道用于和CPU单元连接的扩展单元的输出通道。保持继电器具有断电保持功能，即当电源掉电时，它们能够保持掉电前的ON/OFF状态。4.暂存继电器TR的作用是什么？答：暂存继电器TR位可以用在具有一个以上输出分支的地方作为一个暂存工作位。当一个梯形图程序不能用IL或ILC编程时，可以使用TR。二、读题分析题6.图所示为异步电动机的能耗制动控制线路，试分析核电路的工作过程。答：控制线路工
6、作过程如下：按下起动按钮SB2接触器KM1通电并自锁，主电路中其常开触点闭合电动机启动)。 4下图所示为三相鼠笼式异步电动机串电阻起动控制线路，说明电路中FU和FR的作用，并分析该电路的起动过程。答：按下起动按钮SB1接触器KM1得电，电源通过电阻R加到电动机定子绕组上，降压起动。由时间继电器控制其降压起动的时间，时间继电器延时时间一到，其常开触点闭合，使接触器KM2的线圈得电，同时接触器KM1和KT的线圈失电，电阻R从电网中切除，电动机在正常电压下运行。FU是熔断器，起短路保护作用；FR是热继电器，起长期过载保护作用。6.下图所示为机床工作台自动往复行程控制的电路，行程开关ST1、ST2分别
7、装在机床床身的两侧需要返回的位置，挡铁装在工作台上。试分析该电路的工作过程，并说明行程开关ST3、ST4以及接触器KM1、KM2的常闭触点的作用。答：线路工作过程如下：按下起动按钮SB2，接触器KM1得电自锁，电动机正转，工作台前进，当完成预定行程后，挡块压下ST1，ST1常闭触点断开，切断接触器KM1，同时ST1常开触点闭合，反向接触器KM2得电，电动机反转，工作台后退。当后退到位，挡块压下ST2，工作台又转到正向运动，进行下一个工作循环。直到按下停止按钮SB1工作台才会停止。行程开关ST3、ST4分别为正向、反向终端保护行程开关，当ST1、ST2失灵时，避免工作台因超出极限位置而发生事故。
8、接触器KM1和KM2的常闭触点互相串在对方的线圈回路中，可保证正、反向接触器KM1和KM2不能同时闭合，以防止电源短路。三、改错题7. (1) 答：(2) 答：（3）答：四、根据梯形图写出梯形图指令8. 答： LD NOT 00005 AND 00006 LD 00002AND 00004OR LDAND 00001 AND NOT 00003 LD 00008AND NOT 00009OR LDAND 00007 OUT 00100 END6. 答： LD 00000 AND 00001 LD 00100 AND NOT 00101 LD NOT 20000AND 20001OR LDAND
9、 00102OR LDLD 00002 AND NOT 00003 AND 00004 LD NOT 00103 AND 00104AND NOT 20002 OUT 01000OR 20003OR LDAND LD8. 答：LD 00000 AND 00001 LD 00002 AND NOT 00003OR LD LD 00004 AND 00005 LD 00006AND 00007OR LD AND LD 20002 OUT 01004 END 五、设计题(26分 9.一台三相交流电机驱动机床工作台前后运动.SQ1和SQ2为限位开关，安装在机床前后的预定位置上。当按下启动按钮SB1 ，
10、电动机正转，机床工作台向前运动，当运行到终端位置时，装在机床工作台上的挡铁(撞块碰撞限位开关SQ1，电动机反转，机床工作台向后运行，当运行至终端位置时，装在机床工作台上的挡铁撞块碰撞限位开关SQ2，电动机正转，机床工作台又向前运行，不断往复运动;停机时按下停机按钮SB2.电动机停下来，机床工作停止住复运动。过载时热继电器FR动作，电动机停机。按上述工作要要求:(1)设计电机控制回路;(2)选择PLC，设计PLC控制回路;(3)分配I/O通道，画出梯形圈。 答： (1)图（a）为电机控制主回路，图(b)为PLC控制回路，图( c)为控制梯形图。选CPM1A10点PLC(也可以选其它型号PLC)（
11、2）I/O分配启动按钮 SB1 00000 停止按钮 SB2 00002热保护 FR1 00003 机床前端行程开关 SQ1 00004机床后端行程开关 SQ2 00005 电机正转控制接触器 KM1 00100电机反转控制接触器 KM2 001017.由两台三相交流电动机M1、 M：组成的控制系统的主回路和PLC控制电路如图所示。按起动按钮SBI ,M1电动机起动，过5秒后M2电动机起动，按停止按钮SB2，电动机M1、 M2停止；若M1电动机过载，则电动机M1、M2停止。按上述工作要求：(1)分配I/O通道；(2）画出梯形图。答：(l)I/O点分配启动按钮 SB1 00000 停止按钮 SB
12、2 00001 热保护 FR1 00004输出接触器 KM1 00200 输出接触器 KM2 00201 时间继电器 TIM 000(2)梯形图9.三台电动机M1、M2、M3按下面的顺序启动和停车：启动时，M1、M2同时启动，此后10分钟M3才能启动；停车时，M3必须先停，M3停后5分钟M1、M2同时停。按照上述要求，作I/O分配，画出PLC外部接线图，并设计一个满足要求的梯形图程序。答：I/O分配：启动 00000 停车 00001 M1线圈 01001 M2线圈 01002 M3线圈 01003 中间继电器 01000PLC外部接线图：梯形图：England, has been passe
13、d fit after a lower-leg injury, while Slater has been named at full-back but is still recovering from a knee injury aggravated against USA.Both sides boast 100% records heading into the encounter but Australia have not conceded a try since Josh Charnleys effort in their first pool match against Engl
14、and on the opening day.Aussie winger Jarryd Hayne is the competitions top try scorer with nine, closely followed by Tuivasa-Sheck with eight.But it is recently named Rugby League International Federation player of the year Sonny Bill Williams who has attracted the most interest in the tournament so
15、far.The Kiwi - with a tournament high 17 offloads - has the chance of becoming the first player to win the World Cup in both rugby league and rugby union after triumphing with the All Blacks in 2011.Id give every award back in a heartbeat just to get across the line this weekend, said Williams.The (
16、lack of) air up there Watch mCayman Islands-based Webb, the head of Fifas anti-racism taskforce, is in London for the Football Associations 150th anniversary celebrations and will attend Citys Premier League match at Chelsea on Sunday.I am going to be at the match tomorrow and I have asked to meet Y
17、aya Toure, he told BBC Sport.For me its about how he felt and I would like to speak to him first to find out what his experience was.Uefa hasopened disciplinary proceedings against CSKAfor the racist behaviour of their fans duringCitys 2-1 win.Michel Platini, president of European footballs governin
18、g body, has also ordered an immediate investigation into the referees actions.CSKA said they were surprised and disappointed by Toures complaint. In a statement the Russian side added: We found no racist insults from fans of CSKA. Baumgartner the disappointing news: Mission aborted.The supersonic de
19、scent could happen as early as Sunda.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level
20、of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the bou
21、ndary layer (called the tropopause),e can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.They blew it in 2008 when they got caught cold in the final and
22、 they will not make the same mistake against the Kiwis in Manchester.Five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was scored by Englands Josh Charnley in the opening game of the tournament.That could be classed as a weaknes
23、s, a team under-cooked - but I have been impressed by the Kangaroos focus in their games since then.They have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, especially on their own goal-line, completing sets and a good kick-chase. Theyve been great at al
24、l the unglamorous stuff that often goes unnoticed in the stands but not by your team-mates.It is as though their entire tournament has been preparation for the final.In Johnathan Thurston, Cooper Cronk, Cameron Smith and either Billy Slater or Greg Inglis at full-back they have a spine that is unmat
25、ched in rugby league. They have played in so many high-pressure games - a priceless asset going into Saturday.The Kiwis are a lot less experienced but winning a dramatic match like their semi-final against England will do wonders for their confidence.They defeated Australia in the Four Nations final in 2010 and the last World Cup, and know they can rise to the big occasion.
