This page contains a Flash digital edition of a book.
How do transformers work? By Tom Tate


If we were to ask you to de- scribe KEC’s system, you might say, “Poles, wires and those round grey things.” Round grey things? That is often the de- scription given for transform- ers, the pieces of equipment crucial in converting electricity to a voltage that is safe for use in homes and businesses. So, how do they work? First off, transformers are nothing like those creations of


the silver screen. transform They


don’t transform from vehicles to incredible combat robots. Instead, they


the


voltage of the electricity that passes through them. Time for a little electric system 101. Electricity loses voltage as it is transmitted due to the resis- tance in wires and other com- ponents. As a result, higher voltages are used to offset these “line losses,” as we call them. It all starts at the power plant. There, generators pro- duce electricity at very high voltages and use transformers to step up this voltage, often to 67,000 – 138,000 volts. Since the power plants are far away, these voltages are necessary to survive the trip over the sys- tem to where it is needed. Transmission lines connect to substations brimming with transformers and other control gear. Here is where the trans- formers step down the voltage to safer, more manageable lev-


els. Depending upon the dis- tance involved to the furthest member and the amount of load served, distribution volt- ages can range from 7,200 to 24,900 volts. A couple more step-downs and the electric- ity arrives at your home at 440 volts. This is quite different from the original voltage. Regardless of the shape and size of the transformer, they all work in the same manner. Transformers have two sides, a high-voltage side and a low- voltage side. In normal opera- tion, electricity flows into the transformer on the high-voltage side, where it goes into a coil of wire usually wound around an iron core. As the electricity flows through this coil, it cre- ates a magnetic field that “in- duces” a voltage in the other coil. Here is where the magic (aka physics) of transformation takes place. Each coil has a different number of turns. The greater the number of turns, the higher the voltage. The coil on the high side will have more turns than the one on the low side. As a result, the voltage in- duced on the low side is less. Then transformation occurs. Transformers aren’t just lim-


ited to utility use. They can be found everywhere in our daily lives, even if not so obvious as those on KEC’s system. The best example is the charger that all cell phones and many


other electrical devices come with. These small cousins of utility transformers basically perform the same function. Charging your cell phone with 120 volts will fry it instantly. So, the charger converts the volt- age to a more tolerable 5 volts or so. Take a moment to look around your home and see just how many of these miniature transformers you have. You might be surprised!


It is important to note that transformers work in both di- rections. Electricity flowing in on the low side is stepped up to the voltage of the high side. This is why KEC educates members on proper connec- tion of home generators. A gen- erator feeding 220 volts into a residential transformer will produce whatever voltage the transformer is rated for on the other side, creating a deadly risk for our line crews and your neighbors. So please, connect your generators according to the manufacturer’s recommen- dations. Or give us a call at 1-800-535-1079 for advice. It’s always best to be safe.


Tom Tate writes on cooperative issues for the National Rural Elec- tric Cooperative Association, the Arlington, Va.-based service arm of the nation’s 900-plus consum- er-owned, not-for-profit electric cooperatives.


Crisp morning at United REMC, Markle Indiana. Photo by Cindy Barton. 4


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134