1. Calculate motor speed in revolution per minute for an 8 pole,50Hz motor. Give
ID: 1845990 • Letter: 1
Question
1. Calculate motor speed in revolution per minute for an 8 pole,50Hz motor. Give the equation and identify its parts; show your math.
2.You need to detect finished products coming down an assembly line.Would you use a presence sensor or condition sensor? Why? Which type would be a logical choice?
3.You're designing both personal computers and programmable logic controls.Which type of memory would you choose for each,PROM or EPROM. Why?
4.What is the fundamental benefit of PLC controls over manual controls?
5.Describe the differences between two methods of scanning during PLC logic solving. Which method holds the advantage over the other?
6.Why are gate arrays that are capable of handling the mathematical functions of multiplication and division usually considered unnecessary?
7.Define,compare,and contrast a passive hub and an active hub.
8.Name three improvements Microsoft was able to take advantage of by deciding to write Windows NT from scratch instead of enhancing the then current Windows 95.
9.Name two advantages of fiber-optic cable over coaxial or twisted-pair cable.
10.You're installing a LAN and are running burn in tests. Describe what you're doing and why.
11.Name three types of wireless LAN systems,and discuss the advantages or disadvantages of installing them compared to wired systems.
Explanation / Answer
1. the motor speed,number of poles , frequency relation is given as
Speed = 120*f/number of poles.
so 8 pole,50 Hz.
spped would be 120*50/8 = 750 rpm.
2.Presence sensors would be logically used in this case , but we need to check for unfinished or defective objects as well,so condition sensors are used.
3.EPROM should be used in PCs since it is erasable and minor changes and bugs can be removed at any time. In PLC , we need a fixed functio , so using PROM would be beneficial.
4. PLC contol is vey beneficial over manual control , since if the chance of errors are low and efficiency is high.
5.Program (ladder logic) scanning typically takes place left to right across each rung and from the top to bottom rungs, in order
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