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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 signal alternates abruptly between -1V and +2V with a duty cycle d. sketch a waveform, and find its full cycle average if d=25%, 50%, 75% for what value of d is the full wave average 0
Design a Mealy sequential machine with two inputs A and B, and one output Z. Output Z generates 1 if: (a) A had the same value at each of the two previous clock ticks, or (b) B has been 1 since the last time that the first condition was true.
To avoid changing amplitude scales onthe oscilloscope during the demonstration, suppose that you wantthe resistor voltage (in both circuits), the capacitor voltage, andthe inductor voltage to have the same magnitude. Find the required relationship..
An isolated Free electron is traveling through an electric field from some initial point, where its coulombic potential energy per unit charge(voltage) is 17 KJ/C and velocity = 93 Mm/s to some final point where its coulombic potential energy per ..
Although sums behave like integrals, because of the discrete nature of the sums one needs to be careful with the upper and lower limits more than in the integral. To illustrate this, consider the separation of an integral into two integrals.
120V, 60 Hz source is connected to a distribution line whose resistance, and inductive reactance is 0.001Ohm, j0.002 Ohm, respectively. Single phase, 100HP, 120V, 0.85 pf. motor and 100Kw, 120V heater are connected in parallel.
What frequency must be used for basis symbols f1 = sin(pi*ct) and f2 = cos(pi*ct) with a symbol period of 1/(9600Hz) to contain 6 cycles of the sin and cos
A Si sample is uniformly doped with phosphorus at 5 E 16 cm^-3. We make a p-n junction by implanting boron atoms into the surface layer. The implanted depth is 0.15 µm. What should the surface concentration of the boron implant
Four voice signals. each limited to 4 kHz and sampled at Nyquist rate are converted into binary PCM signal using 256 quantization levels. what will be The bit transmission rate for the time-division multiplexed signal.
Discuss how the angle of the incident light affected the solar cell? How could solar cell designs and/or installations be designed to counter this affect?
q in addition to not dissipating power a lossless line has two important features i it is dispersion less up is
If the thermometer is placed in a bath, the temperature of which is changing linearly at a rate of 10degrees/minute, how much error does the thermometer show
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