Electrical engineering - Basics Page 33

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4.5 Exercises

  1. In order to display the level of a tank filled with a liquid a capacitive level indicator is used. The capacitive level indicator in this case works like a capacitor (two insulated plates separated by a liquid). The level indicator was calibrated for use in a fuel tank but now should be used in a gasoline tank. The size of its plates is 30mm x 60mm, the distance between the plates is 8mm.
    The dielectric constant for fuel is r = 2,0, the dielectric constant for gasoline is = 1,4. Determine the capacity change if instead of fuel, gasoline is filled into the tank.

  2. A disk capacitor has a diameter of 16mm and is 2mm high, its capacity is 4,7nF. Between the capacitor plates there is a ceramic disk. Determine the dielectric constant of the ceramic material.

  3. A mains voltage of 230V is to be transformed to 24V. The primary coil has 770 windings. Determine the number of windings of the secondary coil.

  4. The total number of windings of an autotransformer is 900. The transformer is designed for a 110V connection.
    a) Determine how many windings are necessary to obtain a voltage of 40V.
    b) Determine after how many windings a voltage of 60V has to be applied so that one obtains an output voltage of 230V.

  5. Make a list of all the different kinds of engines you were dealing with at your workplace so far. Write down in which devices and installations these different kinds of engines had been installed. Name possible peculiarities and discuss the results with your course or group members.


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