ChandlerHetrick_Lab6_SeriesParallel_DC_3085L_521L

3. Discuss the limitations in the application of Kirchhoff's laws to railway and other power systems. In what manner do these circuits differs from the usual battery circuits in which the emfs and resistances only are given?

2

Discuss typical structure of the modern electrical grid. Include all elements and provide short description of their role in the system

Questions: 1. Are the experimental and theoretical values of voltages and currents match? Indicate the percentage of differences. 2. Give possible reasons for any discrepancies

The exciting current of an electromagnet is rated at 12 amperes. When connected across a 122 - volt source the current is 14 amperes. Determine the ohms in a resistor which must be connected in series to limit the current to (a) rated value, and (b) 9 amperes.

22. The voltage applied to the h.v. side of a trans- former during short-circuit test is 2% of its rated of voltage. The core loss will be........percent the rated core loss. (a) 4 (b) 0.4 (c) 0.25 (d) 0.04

1- A). Which of the following could be used as a discharge device in an inductive AC circuit? a) resistor b) diode c) metal oxide varistor d) "a" and "c", not "b" B. What is the purpose of a discharge device used in conjunction with opening a highly inductive circuit? a) to minimize the possibility of damage to the circuits insulation as a result of a high induced voltage b) to minimize the possibility of endangering the life of the person opening the controlling switch c) to allow the magnetic field to gradually collapse, thus limiting the value of the self-induced ernf d) all of the above C. The high voltage induced by an inductor when its circuit is opened could be used constructively for a) an automotive ignition system b) an electric fence c) both "a" and "b" d) neither "a" nor "b"

Three phase Bridge rectifier operated from a 380V, 50Hz source throughout three-phase Y/Y connected transformer with ration 2:1. The load current has continuous character with negligible ripples and average thyristor current of 15A. The circuit inductance per phase is 1.2mH. The rectified voltage due to overlapping angle is 90 % of that voltage when this angle is neglected. 1- How much will the voltage drop be due to circuit inductance * 2- How much will the dc average voltage Vdc(alpha) be. 3- How much will the firing angle be ? 4- The overlapping angle. 5- How much is the percentage change of the output dc power if the thyristors T2, T4 and T6 are replaced by three diodes D2, D4, D6. 6- How much will be the maximum RMS phase current for the mentioned in previous task circuit ( semi-converter). 7- If an additional of 1 mH inductances are added to the existing inductances in the phases , how much will the overlapping angle be. The dc load current is kept constant & the…

Q1. a) An SCR based AC power controller circuit is given in Figure 1. The circuit connects a 240V 50Hz AC source vi to a resistive load with resistance of 100. If the delay angle is a-15°, draw the waveforms of the load voltage Vo, and the voltage across SCR2. Calculate the power supplied to the load. + Vi Va + 2 SCR2 H₁₁ SCR₁ Figure 1 SCR based AC power control circuit Va + 2 io b) Figure 2 is a single phase 2-level voltage source converter (VSC) with a DC voltage Vd-200V. A PWM scheme, by comparing a reference value with a 10kHz triangle waveform, is used to control the switches S₁ and S2. The modulation index of the PWM is m=0.8. With the aid of graphs explain how pulse signals for the switches are generated, sketch the output voltage Vo, determine the duty cycle, and calculate the average output voltage. + Vo + Vo √ ₂ == Figure 2 A single phase VSC