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It is shown that impedance measurements can be used to quantify transmission line damage. A device design is given for detecting the complex impedance of a transmission line at high frequencies without disrupting regular service. A complementary device is presented that simulates an open circuit at the excitation frequency at some distance from the excitation source, thus increasing the sensitivity...
Based on Global Positioning System (GPS), a new method to measure the zero sqeuence impedance of transmission lines by using the two-terminal measured voltage and current data of lines is proposed. The mathematical model of the new method is explained in detail. The hardware structure of the measuring system based on GPS technology is given. Digital simulation results with different frequencies of...
The objective of this paper is to show a methodology to estimate the longitudinal parameters of transmission lines. The method is based on the modal analysis theory and developed from the currents and voltages measured at the sending and receiving ends of the line. Another proposal is to estimate the line impedance in function of the real-time load apparent power and power factor. The procedure is...
This paper is focused on optimizing the distance protection algorithm for series-compensated line. This algorithm requires estimation of three-phase voltage drops across capacitors bank. For this purpose a nonlinear differential equation is solved on-line, applying comparatively low sampling frequency. In order to assure high fidelity of the waveforms reconstruction using the up resampling procedure...
Distance relays are widely used as main and back-up protection for transmission lines. Their operation is based on impedance measurement at the relaying point, which can be affected by several factors, including pre-fault line loading and short circuit levels at the line ends. Continues demand for electricity energy leads to increase of short circuit levels along the network, which itself causes new...
Summary form only given. For pulsed power machines with an inductive voltage adder (IVA) architecture and a magnetically insulated transmission line (MITL), positive polarity operation results in layered MITL flow as emitted electrons are born at different potentials in each of the adder cells. Because of this layered flow, the usual prediction of the voltage using the Mendel formula is not accurate...
Based on Wide Area Measurement System (WAMS), a new method for live line measuring the impedance parameters of transmission lines with mutual inductance is proposed. The mathematical model of the new method is explained in detail. The new method uses no extern voltage source and it only uses the zero-sequence interference voltages among the transmission lines as the measurement sources. The hardware...
This paper presents a fully integrated 60 GHz two stage power amplifier using cascode topology. The design procedure and measurement results are presented. The PA is implemented in a 0.25 μm SiGe:C BiCMOS technology featuring ft and fmax ≈ 200 GHz. The saturated output power of the amplifier has been improved with the help of current combining and matching techniques. At 60 GHz the power amplifier...
A typical electronic systems with long signal transmission line illuminated by an ultra-wide band (UWB) pulse generator has been presented The test shows that: interference will be induced into the ground equipment, and working signals will be distorted under such condition. An `antenna model' of the transmission line is presented The main reason of the interference induced into the system is that...
This paper is focused on the development of the new principles and operational algorithms of the transmission lines distance protection. The proposed distance protection algorithms utilize statistical information about the undefined and random parameters and quantities such as equivalent impedances of the systems at the unmonitored end of the power transmission line and current and voltage phasor...
This paper analyzes a 300 ohm primary ground fault, which is an unusually high value for a 525 kV transmission line in southeastern Brazil. This case study emphasizes the techniques used by the analysts. Considering that the fault impedance was larger than those usually observed in single-phase faults on extra-high-voltage (EHV) lines, this paper discusses the probable cause of the fault and mentions...
Transmission lines that are terminated into transformers are applications where the line and transformer cannot be separated by a circuit breaker and are therefore in the same zone of protection. These applications may be addressed with either current differential or line distance protection. In either case the implementation of separate transformer differential protection isolating the protection...
Distance relays are widely used as main and back-up protection for transmission lines. Their operation is based on impedance measurement at the relaying point, which can be affected by several factors, including pre-fault line loading and short circuit levels at the line ends. Continues demand for electricity energy leads to increase the short circuit levels along the network, which itself causes...
Distance relays are widely in use as main and back-up protective devices for transmission lines. Their operation is based on impedance measurement at the relaying point, which can be affected by several factors. Continued demand for electricity energy leads to increase in the short circuit levels along the network, which itself causes new problems. One of the proposed solutions for this problem is...
The influence of elevated objects, when they are hit by lightning, on the measured lightning currents and associated fields is studied. For the present study, an electromagnetic model of return strokes with the help of NEC-4 is employed. Cases of strokes to ground, to independent towers, and to a transmission line are compared and the validity of comparison is discussed. The influence of the independent...
Device testing using an IEC-compliant hand-held 150 pF/330 Omega discharge gun was compared to a 50 Omega IEC waveform pulser. Current waveforms were recorded and components tested with both pulsers. To understand effects of different pulse source impedances, the 50 Omega pulser was modified to operate at 100 and 330 Omega delivery impedances.
Standard 50-ohm TDR TLP systems do not accurately measure the clamp voltage and minimum holding currents of snapback ESD protection structures. Two methods are presented that can accurately determine device operation at the turn-on point. Multilevel TLP generated with charge lines is contrasted with 100-to-1000-ohm TDRT for snapback parameter determination.
Very fast transmission line pulse (VF-TLP) systems described in the literature are time domain reflection (VF-TDR) configurations. Using other TLP configurations, VF-TLP systems can provide new capabilities. A wafer level Kelvin probe system was derived from VF-time domain transmission (VF-TDT). A test fixture board (TFB) using VF-time domain reflection and transmission (VF-TDRT) enables VF-TLP package...
A novel TLP testing approach, multilevel TLP (MTLP), is described, which can yield accurate and comprehensive snapback IV measurements unlike in the conventional TLP testing methodology with different system impedances. The experimental validity of the MTLP methodology and setup are demonstrated with measurement results from different snapback devices.
TLP systems are mainly classified by their impedance, such as 50 ohm or 500 ohm current source. A new TLP configuration allows switching between 50 and 500 ohm by computer control to characterize a given part using both impedances. In addition, a four-needle Kelvin technique is introduced to TLP, which overcomes the measurement error from variations in contact resistance where the probe needles contact...
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