in a closed loop control system, explain how the load is always driven towards its demanded output value.?
605844
Practically, the output isn't always driven to the reference value.  If the output is affected by very large disturbances, the system simply cannot always compensate.  eg: a car's cruise control trying to get the car to top speed up a very steep incline.  Also, it depends on what input reference signal is given.  eg: you try to get the car to follow some crazy speed profile like a sine wave and it may not follow the input well.\n\nAnyway, feedback control systems are usually designed to have zero steady state error at the output for a constant step input.  How is this done?  \n\nThe output is fed back and compared with the reference signal and then the difference is fed to a engineer-designed compensator block.  The compensator then leads to the plant block (the system we are trying to control).\n\nThe compensator is one of the key things here.  It is designed using some special control techniques such as root locus or Bode plot design or simply guess and check with a design program like Matlab.  Basically, the compensator acts on the difference between the output and the input reference in such a way as to create an appropriate signal to the plant.  Depending on whether you go with digital or analog control, the hardware designed to do all this varies.
141538
Read the references at the end of the article or talk to an industrial engineer.\n\nhttp://en.wikipedia.org/wiki/Linear_programming
107875
Limit the load current.\nEDIT: This is often done by adjusting the stator field current if it's a generator with an electromagnet (not permanent magnet) field.
761223
hi \nIn college labs what ever the techniques used for controlling the speed to control are the methods employed in indusrties also.but as for a glance they look other method in industries.\nmost common methods are-\n\ncontrol of terminal voltage\ncontrol of field current \netc.
495540
Open-loop which is mentioned here, refers to a systems control concept, named feedback. If you don't provide a feedback to correct the input commands, the system is called open-loop. If feedback is applied, it is closed-loop. An example of open-loop is a hydraulic pump actuated by a dc/ac  motor, adjusting its flow rate by controlling applied voltage to motor. No feedback compensates the errors in flow, therefore ot is called open-loop.
895025
no. there is no such case , theroretically. because, according to the law of conservation of energy the total energy in any closed system is constant. however practically some energy is dissipated in a practical case.
520009
Another rule of thumb is to assume 100% load. \n\nNot knowing what kind of "electric motor calculations" you are going to make it is difficult to say what load factor you should use.
716085
You can't make a perpetual-motion machine, if that's what you're getting at. Whatever loop you make, you'll always end up losing energy until it stops, unless you are putting energy in (solar) but then what's the point?
774945
It is the line connecting Vcc/Rl and Vmax on the transistor VIcharecteristics V on the x axis and I on the Y axis. Where it cuts the charecteristics we get the quiscent point or the operating point. This is the mean point,  the output current varies sinusoid beyond and below this point on the load line.
589794
Formulate stability of the system as a function of its energy. Now, one has to show that minimum energy translates into max stability on finding the derivatives.
677947
supplies the power at the appropriate rate for the computer to function properly
1092236
Infinite when the switch is open.\n\nLittle or zero when the switch is closed.
399764
If there is demand, there will be supply. They work side by side. One cannot exist without the other. As one increases or decreases, so will the other. Not always at the same rate of increase or decrease. This rule determines cost of production & selling price. On a simple grid, using a X & Y axis; where they cross is the selling price.
613947
Wind power plant output depends on wind speed. Such speeds cannot be accurately predicted over daily periods because the wind fluctuates from minute-to-minute and hour-to-hour. Consequently, electric utility system planners and operators are concerned that variations in wind plant output may increase the operating costs of the system. This concern arises because the system must maintain balance between the aggregate demand for electric power and the total power generated by all power plants feeding the system. The operators' concerns are compounded because unlike conventional power plants that are generally under their control and thus are dispatchable, the wind plants are controlled by nature. \n\nIt should be understood that the key issue is not whether a system with a significant amount of wind capacity can be operated reliably, but rather to what extent the system operating costs are increased by the variability of the wind.
820019
Efficiency is always output work over input work. The 600 lbf. load is irrelevant.
980113
Do you want to know if it is a negative or positive feedback control mechanism?  If so, it is a negative feedback control mechanism.\n\nNot sure if that is what you are looking for.
347168
Energy that enters the system from the surroundings.