Power Engineers Window

  Motor Testing by Test Lamp Preamble This is regarding testing of three phase squirrel cage induction motor. As known stator has winding whereas rotor has only conductor bars connected to end rings at both ends. So probability of fault is negligible due to sturdy construction. Any damage is detectable by visual inspection only. Numbers of coils are coils placed in different slots of core in stator as per design. These coils are interconnected in three groups for three phases. Six ends of three groups are taken out in terminal box for external connection with supply. They are marked like A 1 -A 2 ,   B 1 -B 2 and C 1 -C 2   or R 1 -R 2 ,   Y 1 -Y 2 and B 1 -B 2 Motor is subjected to abnormal operating conditions like high voltage or voltage surge, over heating due to over load, low supply voltage or single phasing. So there is possibility of damage or degrading of insulation resulting in current leakage to body, between phases or between turns of the coil. Ov...

  Power   Work is manifestation of energy. Work done = Energy Consumed. Application of Force (Pressure) to any object results in its movement (Displacement) Work done is applied Force multiply by Distance moved by object in the direction of force.   Work = Force × Distance (in direction of force)   Dividing by Time, we get        Work                         Distance -----------   =   Force ×   -----------    Time                          Time   Work divided by time is Power.  Distance divided by time is Velocity (in direction of force)   Therefore     Power = Force × Velocity   OR   P = F × V ...

  Lamps in Series Comparison of light outputs in following two cases. A. One lamp rated 250 Volt 100 Watts is connected across 250 Volts supply. B. Two lamps rated 250 Volts 100 Watts are placed side by side and connected in series across 250 Volts supply. How is light output in case B as compared to in case A. 1.        More than double 2.       Double 3.       Less than double 4.       Equals 5.       More than half 6.       Half       7.       Less than half                           and How?   Answer Readers, Quiz is a mental exercise to enhance reasoning power in the subject. Hence personal attempt for reply is expected before jumping to answer. Answer given here is just for c...

  Transmission Lines   Once there was a question from the audience as under. Inductance and capacitance of transmission line depends on its length, conductor size, separation and configuration etc. But particular line has fixed R, L & C. While in operation this line is acting as source or sink of the reactive power. How this happens? This requires review of transmission line fundamentals. As resistance of line has no role in this aspect, we concentrate only on L & C of line. Inductance of the line is along the conductor and capacitance is between the conductors spread over the line as in the figure. Only one pair i.e. two conductors are shown for clarity.   In fact each of the three conductors has inductance and each of three pairs of conductors has capacitance.   In equivalent circuit of the line total inductance L and total capacitance C of the line is considered as lump and represented in the form of Tee or π form as under. Line capacitance i...