In conclusion, the author established a Maxwell electromagnetic field simulation model based on ANSOFT software to analyze the mechanism of the open-close current transformer. According to the simulation results, the voltage waveform, transient magnetic flux, excitation current, and other characteristics of the open-close current transformer were analyzed. Specific simulation graphs and data were provided, and the amplitude-frequency characteristics of the excitation current were analyzed using Fourier transform. 4. If the fuse replacement trial fails, all fuses in the 35kV feeder and main transformer voltage circuits should be removed, including the central signal and low-frequency panel. When an open circuit occurs, due to the increase in magnetic flux density and the non-sinusoidal nature of the magnetic flux, the vibration force on the silicon steel sheets increases, resulting in louder noise. Since u=u c, it follows that u=u c =u 1? ０? 6c 1 /(c 1 +c)=k u u 1 (7- where k u -- voltage ratio, k u =c 1 /(c 1 +c) Since u is transformed proportionally to the primary voltage u1, u can be used to represent u1, thus allowing the measurement of phase-to-ground voltage.
1. Luxe type - Rated primary voltage for the response of the split-core current transformer. In case of a short circuit, a fuse should be used for protection. If the meter indicates intermittently, it may be in a semi-open circuit state due to poor contact. Figure 4: The second kind of elementary secondary circuit of a 4-phase voltage transformer. When a single-phase grounding occurs, the output value of the open-delta output will not be reduced due to this wiring. At this time, the potential at point l is between the grounding phase voltage and the ground potential (0 potential). When applied to the faulty phase pt, it simply pulls the potential at point l in the diagram to the actual operating state. Because during normal operation, the three-phase voltage is balanced at the neutral potential.
The secondary winding rated voltage of the split-core current transformer is selected according to the following table: Winding Main secondary winding Auxiliary secondary winding connected to zero-sequence voltage Winding connection Line voltage Phase voltage In a power grid with neutral point directly grounded In a power grid with neutral point not directly grounded or grounded via an arc suppression coil Secondary voltage v 100 100/3 100 100/3 The residual winding of the split-core current transformer, including its capacity and accuracy class, shall meet the requirements of measuring instruments, protective devices, and automatic devices.
(2) For the operation and monitoring of on-off current transformers used in watt-hour meters, power meters in power plants, and voltage relays, the accuracy level should be selected as Class 1. The winding voltage of 0.91 V is not very significant because it is only close to the required 100 V generated by the non-fault phase pt. The polarity of the current transformer is generally marked using the subtractive polarity principle, which means that the current in the secondary winding induces a magnetic flux in the iron core with opposite direction. Generally, the rated capacity refers to the capacity corresponding to the accuracy level. In systems where the neutral point is not grounded or grounded through an arc suppression coil.
(3) The accuracy level of the open-close current transformer used for meters that measure the value of the quantity being measured, such as voltmeters and voltage relays with only one coil, is Class 3. It has been confirmed that due to the open circuit of the neutral line in the secondary circuit, interference signals enter, resulting in the generation of third-order harmonics in the secondary circuit.
