![]() This switching produces no current asymmetry. In this test, the breaker is closed at a peak of source voltage (t = 1.25 cycle). This switch will be used later to illustrate overvoltages produced when CT secondary is left open. The switch connected in series with the CT secondary is normally closed. The CT flux, measured by the Multimeter block is converted in pu and sent to trace 2. The primary current reflected on the secondary and the voltage developed across the 1 ohm resistance are sent to trace 1 of the Scope block. The CT is assumed to saturate at 10 pu and a simple 2 segment saturation characteristic is used. Open the CT dialog box and observe how the CT parameters are specified. In steady state, the current flowing in the secondary is 1000*5/2000 = 2.5 A (2.5 Vrms or 3.54 Vpeak read by the voltage measurement block V2). A voltage sensor connected at the secondary reads a voltage which should be proportional to the primary current. The secondary winding consisting of 1*2000/5 = 400 turns is short circuited through a 1 ohm load resistance. The primary winding which consists of a single turn passing through the CT toroidal core is connected in series with the shunt inductor rated 69.3 Mvar, 69.3 kV (120kV/sqrt(3)), 1 kA rms. A current transformer (CT) is used to measure current in a shunt inductor connected on a 120 kV network.
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