test1 power

8/4/2019 Test1 Power

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Test I EEL 321 IRead the questions carefully; show your work for creditWrite hard on each page and try to remember to use only thefront of the page to write on (for scanning purposes)Turn in all worksheets with your testStaple all together (in correct order) and be sure to put yourname on the front of the test and at least initials onworksheets.. Remember that all of your answers should be in mks s stem.Read each question carefully and fill in the answer in theunderlined area given in each section.


2/13

RPM - 60 revlmin

Problem 1. A mass is to be hoisted from a lower level to a higher level (helicopterlifting a person), using the motor with pulley shown. The weight of the mass is 160pounds and the diameter of the pulley is 20 inches. After the mass is in motion, the speedof the shaft remains at a constant 60 revolutions per minute during the entire travel. Theefficiency of the motor/shaft is 100% (loss-less) and the input voltage applied to themotor is 120 volts RMS.(Hint: There are 16 ounces/pound and 28.3 grams/ounce and the gravitational constant, g,is 9.8m/sec'. Newton weight: F: mg.)

Motor


3/13

120 VRMS / l50HzR150

Problem 2. The frequency of the input power source of the above circuit is 150 hertz.What is the ryr facleL real power, reactive power, apparent power, and RMS current(put these answers in the BEFORE CORRECTION section, below)?BEFORE CORRECTION (before adding capacitor)

What is the inductive reactance Xr? fJ*? , '?.::lWhat is the Real power P (before adding coffecting capacitor)?What is the Reactive power Q Oefore adding coffecting capacitor)?What is the Apparent power S (before adding colrecting capacitor)?Power Factor (before adding colrecting capacitor)?What is the RMS current, flowing from Vl ?

Vl Ll0.053


4/13

Voltage input : I20 V RMSCurrent input: 10 A RMS

Problem 3. the input voltage and current to the above system are measured, usingtrue RMS meters, and are known to be:

It is also known that the power consumed by the system is:OUTPUT LOAD REAL POWER- 950 WATTSINTERI\AL SYSTEM REAL PWRLOSSE,S - 50 WATTS

With reference to the POWER TRIANGLE, what is the apparent power, the reactivepower supplied to the system, the system impedance ansle and power factor? Sketch thepower triangle and place the values on the appropriate part of the triangle (include S,Q,P,e).

Apparent Power S (in VAX [ ?PeP

V RMS -I2O VRMS I RMS - 10 A RMS.

SYSTEM


5/13

Left path Right path

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Problem 4. ALL DIMENSIONS ARE IN cm, except for the sap. The above E corehas a relative permeability of 2000 and a 10 mm gap in the center leg (no gaps in theouter legs). The gap is filled with a low perm material ur: 5 in order to eliminatethe fringing flux (i.e. gap is NOT air!) and A_centerleg: A_gap.The thickness (or depth of the core) is 8 cm. The number of tums is 100 and the DCcurrent flowing through the winding is 2 amps. The path(s) are shown for the core fluxfor both sides of the core (above: dark rectangles represent the middle of path).


6/13

Total Reluctance as seen by the source that is driving the total fluIThis total Reluctance isThe flux, 0, in the center leg

The flux, 0, in the left legThe flux, 0, in the right legThe flux density, B, in the center legThe flux density, B, in the left legThe flux density, B, in the right leg

The inductance, L, of the winding (Henries)


7/13

Problem 5. An electromagnetic discharge (local lightning strike) is discharged in thevicinity of a pickup coil (shown below), with such intensity that it produces the S(t) in thedirection shown in the drawing and\ > graph below.0(t)

A

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0.08

0.06,,9,,,!:,)., 0.04


8/13

Sketch the voltage v(t) on the graph to the right of the {(t) plot and label the v(t)waveform values on the Y-axis. (above).

Assuming that you did the V(t) graph, correctly, how would you connect an o-scope tothe coil terminations A and B in order to produce the same waveform as your V(t) graph.In other words, which end of the coil is considered the positive end??(A or B)?_Explain your reasoning briefly below so I can give you credit.. ..


9/13

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10/13

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11/13

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12/13

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13/13

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