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