Power Engineers Window

  Grid Operation Part 1 Standalone Systems Elementary power systems were very simple having generator and loads connected to lines from generator. Mostly these were direct current systems. There was limitation on generator capacity as power generated in armature has to be drawn via sliding contacts of commutator brush assembly. High current through sliding contact cause heavy sparking. Letter on alternating current system were available with higher capacity generators.  Till this time power systems has only two elements Generation and Distribution. Adding generator and operate in parallel was necessitated with increased load beyond capacity of single generator. These systems were standalone type catering local loads in town/city. Catering load at faraway was not feasible due constraint of high power loss and high voltage drop. Such power systems were developed, operated and mange by private party as commercial activity. Roads and streets had telephone line on one side a...

  Answer   They cannot be operated in parallel. Vector group can be modified by changing internal connections for delta of primary winding. It is not possible at site. It can be done at works only.   In Dy01, secondary phase voltages are lagging by 30 degree to respective primary phase voltages. In Dy11, secondary phase voltages are leading by 30 degree to respective primary phase voltages.   However there is simple practical solution.   It is seen that vector diagrams DY01 and DY11 are mirror image of each other. If vector diagram DY01 is flipped horizontally i.e. left–right, it will be similar to DY11. Of course phase sequence is reversed.   Consider two moving persons A and B at some distance. B is at right of A as under. Consider them moving from left towards right. In this case A appears behind (lagging) B. But with persons in the same position, consider them moving from right towards left. In this case A appears ahead (le...

  Dy01 & Dy11 Parallel   There are two transformers having similar ratings in all respect except their vector group is different. Vector group of one is DY01 and other is DY11.   These two transformers can be operated in parallel? ANSWER

  Fridgeyser   Energy saving is important task and achieved by various manners. It may be as simple as using natural substitutes like using day light and breeze instead of electric lights and fans. Anybody can contribute by some simple steps like switching off lights, fans, ACs when leaving the premises. Little care for just required usage of various services may save energy. Limited lighting while watching TV, table lamps on study table, AC operation just at comfortable temperature setting can save energy. Adoption of high efficiency gadgets like LED Light, Star labeled Fan, Refrigerator, AC etc saves energy. Also Cascade utilization, Waste Recovery, etc is implemented for energy saving. Here is one such arrangement for energy saving. Following house hold gadgets are common in almost all homes. Domestic Refrigerator ……….. colloquially Fridge. Hot water system ………………. colloquially Geyser. Fridge The Refrigerator is used for storing eatables at low temperature to ...

  Speed of Alternators and Motors with different loads There are two identical alternators having individual prime mover as shown in the figure. They are connected to a common bus and operating parallel but catering different KW loads. There are also two identical induction motors connected to the same common bus as shown. These motors are running with unequal loads. Load on one motor is more as compared to other. In this condition Speed (RPM) of both Motors can be same or different? Why? Speed (RPM) of both Alternators can be same or different? Why? 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 confirmation. Proceed Answer Motors Motors are running with different loads. Motor slip is proportional to its load. So slip of both motors may be different. Running speed of motor is synchronous speed minus slip speed. Hence motor r...

  Alternators of different numbers of poles There are two alternators having similar rating in all respect except numbers of poles. One is four pole machine whereas other is six pole machine. Is it feasible to synchronize them for parallel operation?

  Energy Conservation Opportunities in Water Supply System of Multi Storey Buildings   As general practice all multi storey buildings have water tank on the terrace. All occupants get their water supply from this tank. Obviously tank size has to be big enough to store sufficient water required for all occupants. Pump-set is provided for pumping water to the tank either from bore well or sump. There is distribution piping network for all apartments at various floors. While examining various alternatives, it is found that there is huge scope for energy saving. This requires radical changes starting from design of the building. Masonry Water storage tank is to be build for each floor instead of common tank at terrace. These tanks may be like column of tanks one over the other. Tank height may be equal to floor height and base as per water storage requirement for one floor only. There will be no tank on ground floor level. Top tank will be on terrace. This means ...

  Answer                                                    Length Actual Resistance R = ρ ×   --------------                                                    Area   But length and cross section area is not specified   Actually length is the dimension along the direction of current and area is across the direction of current.   Therefore there are three possibilities depending upon the direction of the current as under.     ...

  Conductor Resistance   A piece of conducting material having specific resistance ρ has dimensions as per drawing Calculate its actual resistance R in term of ρ, X, Y, Z. ANSWER

  Answer Current I 1   is  R-phase  current which is  5 Amps . Current I 2  is sum of current of  R-phase  &  Y-phase . They are 5 Amps each but 120 degree apart. Vector sum of these two is also  5 Amps  as shown hereunder in vector diagram. Current I 3   is sum of currents in  B-phase  &  Current I 2   (Sum of  R-phase  &  Y-phase) . As these current are equal and opposite, vector sum is zero.                  Vector Diagram                   Ultimtely                              I 1  = 5 Amps                  I 2  = 5 Amps                  ...