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In this chapter, we learned that a step-down autotransformer could be used to reduce the starting current drawn by an induction motor. While this technique works, an autotransformer is relatively expensive. A much less expensive way to reduce the starting current is to use a device called Y-D starter (described earlier in this chapter). If an induction motor is normally D-connected, it is possible to reduce its phase voltage Vf (and hence its starting current) by simply re-connecting the stator windings in Y during starting, and then restoring the connections to D when the motor comes up to speed. Answer the following questions about this type of starter.
(a) How would the phase voltage at starting compare with the phase voltage under normal running conditions?
(b) How would the starting current of the Y-connected motor compare to the starting current if the motor remained in a D-connection during starting?
(a) At t = 0, the current flowing in a 0.5-H inductance is 4 A. What constant voltage must be applied to reduce the current to 0 at t = 0.2 s (b) Starting at t = 0, a constant 12-V voltage source is applied to a 2-H inductor.
Find the Eb/no ratio in dB for a system operating at 10Mbps in a BW of 1MHz. the un-modulated carrier power is 0.1pW and the system noise temperature is 120 degrees Kelvin.
Design an ionospheric radio link over a distance of 2500 Km given that the ionosphere effective height is 275 Km and the electron density N= 2*1011 /m3, namely find : i- the angle of incidence on the ionospheric layer.
The windings of high-current electromagnets are often made of copper pipe. The current flows in the walls of the pipe, and the cooling water flows in the interior of the pipe. Suppose the copper pipe has an outside diameter of 1.2 cm and inside di..
GaAs LED emitting surface size is 180 um by 180 um. The doping levels are NA = 9 E+15 cm-3 and ND = 5 E+17 cm-3. The n-layer is 70 um thick, and the p-layer is 8 um thick.
Write Verilog code of a 4 bit Shift Register circuit which may shift right or shift left depending on control signal ‘M' using structural modeling. Also write the Verilog code of the D Flip Flop using either behavioral or gate level modeling.
What parallel redundancy does to the power distribution system?
If the attenuation coefficient for the wave in equation E =Eoe-αzsin(ωt - kz) has the value 2x 10-5 cm-1, compute the power loss in dB for1 km. Compute the fractional loss for 1 km.
a digital channel is described by 16 QAM, the data rate is 50 Mbps, the bandwidth is 200 MHz, the power is 1 W, and the received noise level is 50 mW. Resolve for SNR, Baud Rate and the Max theoretical bit rate for the channel.
A 4800 bps data transmission device has a bit error rate of 10-6 normally. During a test period, it works at normal conditions except that a 1000ms impulse saturates the channel and all data is lost. Calculate the average bit error rate within the..
Using the mfile window the height and distance traveled by a ball thrown at an angle A and with a speed v is: [h(t) =vtsin(A)-0.5gt^2] , [x(t)=vtcos(A)].
The counter should be designed using D flip-flops and using the state equation method. (No credit will be given if the circuit is designed using the excitation table method.) Draw the final logic diagram.
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