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In the early days of ac motor development, machine designers had great difficulty controlling the core losses (hysteresis and eddy currents) in machines. They had not yet developed steels with low hysteresis, and were not making laminations as thin as the ones used today. To help control these losses, early ac motors in the USA were run from a 25 Hz ac power supply, while lighting systems were run from a separate 60 Hz ac power supply.
(a) Develop a table showing the speed of magnetic field rotation in ac machines of 2, 4, 6, 8, 10, 12, and 14 poles operating at 25 Hz. What was the fastest rotational speed available to these early motors?
(b) For a given motor operating at a constant flux density B, how would the core losses of the motor running at 25 Hz compare to the core losses of the motor running at 60 Hz?
(c) Why did the early engineers provide a separate 60 Hz power system for lighting?
A quartz window of thickness L serves as a viewing port in a furnace used for annealing steel. The inner surface (x = 0) of the window is irradiated with a uniform heat flux q;: due to emission from hot gases in the furnace.
Determine the magnitude of the velocity and acceleration of the car when it reaches point B. Also, how much time is required for it to travel from A to B?
1) Determine the number of possible PCM values that can be encoded for (a) 6 bits and (b) 10 bits. 2)it is desired to represent an analog signal in no less than 500 values. determine the minimum numbber of bits required for each word.
In an RC circuit the voltage is given by V=V0ekt where V0 is the initial voltage and K is a constant. Find out the current through the circuit as a function of time and capacitance.
Design a full-wave bridge rectifier circuit to deliver 10 volts de with less than 0.1 volt (pp) ripple into a load draWing up to 10mA. Choose the appropriate ac input voltage. assuming 0.6 volt diode drops.
A 120 Veff motor draws 1.5 kVA at a lagging power factor of .85. Determine the size of the capacitor that must be placed in parallel with the motor for a power factor of 1.
there is the file named like hs1108 or hs0508 in the course of eel 5840 in university of florida. but i cannot open
An electric flux density is given by D = D0, a rho , where D0 is a given constant, (a) What charge density generates this field (b) For the specified field, what total charge is contained within a cylinder of radius a and height b, where the cylin..
The end of the plates is 30 cm from the tube screen. The kinetic energy of the electrons is 2.80 keV. If a potential difference of 25.0 V is applied across the deflection plates, by how much will the point where the beam of electrons strikes the s..
Single pole amp. has an open loop gain 10^6 and open loop bandwidth of 10Hz. If the feedback factor =1, calculate the gain and bandwidth after the feedback
The voltage across the load must remain between 4.7 and 5.0 V for all values of load current. Design a voltage-divider network to supply the load. You may assume that resistors of any value desired are available.
An experiment is performed 5 times and two measurements are made. X = {1,3,2,5,7} Y = {6,7 8 9,10} Find the correlation coefficient between X and Y.
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