Abstract:
The present disclosure provides a forced symmetry IMD and a method to control the forced symmetry IMD. The system comprises an electric system power source configured to deliver electrical power to a bus, the bus including a first bus bar and a second bus bar; a common node connected across the first bus bar and the second bus bar, the common node having a common voltage; and a forced symmetry insulation monitoring device (IMD) disposed along an IMD node connected to at least one of the first bus bar and the second bus bar, the forced symmetry IMD comprising a connection to ground and one or more IMD power sources, wherein the one or more IMD power sources of the forced symmetry IMD is configured to control the common voltage on the common node based on a currently detected common voltage and a reference voltage signal.
Abstract:
Zum Erfassen eines Isolationswiderstands (Riso) einer an einen geteilten Zwischenkreis (2) angeschlossenen Gleichspannungsquelle (7) wird ein Mittelpunktpotential der Gleichspannungsquelle (7) durch unterschiedlichen Betrieb von zwei Spannungsstellern (11, 12) verschoben, über die zwei Pole (9, 10) der Gleichspannungsquelle (7) jeweils an einen von zwei Teilen (3, 4) des geteilten Zwischenkreises (2) angeschlossen sind. Dabei wird eine aus dem Verschieben des Mittelpunktpotentials der Gleichspannungsquelle (7) resultierende Änderung (I_delta) eines Differenzstroms über alle Leitungen (25, 26; 28, 29) erfasst, die einen über den Zwischenkreis (2) fließenden Strom von der Gleichspannungsquelle (7) führen.
Abstract:
The system (S) for checking the electrical insulation in converters for electric cars comprises at least one voltage generator (G, G1, G2) connected to at least one line (L1-Ln) to be monitored of a high-voltage converter (CNV) for electric vehicles and connected to the ground (C) of said converter (CNV), and at least one current detection unit (U, U1, U2) operatively connected to said voltage generator (G, G1, G2) and configured to detect any current possibly present on the voltage generator (G, G1, G2) and to generate a warning signal in the event of detection of the current.
Abstract:
The invention provides a method for fault location in a power transmission system, with two terminals connected by parallel transmission lines. The fault is located in a first transmission line. The method comprises obtaining measurements of post-fault voltages and currents at one terminal, and measurements of post-fault currents at another terminal of the first transmission line. The post-fault measurements are used to calculate voltage and current phasors for various fault location values. For estimating the phasors for a fault location value, positive, negative and zero sequence voltage and current phasors are calculated for the fault location value. Here, the zero sequence phasors are calculated from the first line measurements, and zero sequence currents estimated for the second transmission line. The zero sequence currents for the second line are estimated with the zero sequence quantities of the first line measurements and line impedance parameters associated the two lines.
Abstract:
The invention refers to a method for detecting earth leakage in the cabling of an insulated electric installation, such as an insulated railway signaling installation, the method comprising the steps of applying through a first resistor (Rel) a first voltage between cabling and ground (PE) and measuring a resulting first current (Imeas). To allow for fail-safe operation and for check of faults in earth leakage detection it is provided that independently from the first resistor (Rel) a second voltage between cabling and ground is applied through a second resistor (Rel) and that the resulting second current (Imeas) is measured, and that first and second resulting current, or variables derived from first and second resulting current, are compared, and that the first resulting current (Imeas), or a variable derived therefrom, deviates by a predefined amount from the current, or a respective variable derived therefrom, resulting from known first voltage and known first resistor (Rel), and the second resulting current (Imeas), or a variable derived therefrom, deviates by a predefined amount from the current, or a respective variable derived therefrom, resulting from known second voltage and known second resistor (Rel).
Abstract:
A continuity test system (100), includes a base unit (1) and a mobile unit (9). The base unit (1) is adapted to be connected to a first portion of a test item, and, the mobile unit (9) is both interconnected to said base unit (1), and adapted to be connected to a second portion of said test item. The continuity test system (100) includes a signal generator (2), adapted to generate a dual polarity measurement signal, a measurement unit (14), adapted to measure electrical parameters of said test item (16)as said dual polarity measurement signal is applied thereto, and, a processor (13, 4), to process said measured electrical parameters and provide a resultant continuity test signal output.
Abstract:
Offenbart wird eine Vorrichtung (V) zur Überwachung einer elektrischen Isolation bei einem Bordnetz (BN) eines Fahrzeugs, mit : - einer Spannungsquelle (SQ) zum Generieren von Gleich-Spannungen mit einem ersten (Uq1) und einem zweiten (Uq2) Spannungswert,- eine Spannungsmesseinheit (ME1) zwischen einer positiven (LP) und einer negativen (LN) Stromversorgungsleitung des Bordnetzes (BN) zum Messen einer Spannung (Ub) zwischen der positiven (LP) und der negativen (LN) Stromversorgungsleitung,- einen Strompfad (P) zwischen einem positiven Stromanschluss (AP) der Spannungsquelle (SQ) und der positiven (LP),- eine Strommesseinheit (ME2) in dem Strompfad (P) zum Messen eines durch den Strompfad (P) fließenden Stromes (I),- eine Ermittlungseinheit (EE), eingerichtet zum Ermitteln eines Isolationswiderstands (R_ISO) zwischen dem Bordnetz (BN) und elektrischer Masse (MA) aus Spannungsmesswerten (Ubl, Ub2) der Spannungsmesseinheit (MEl), Strommesswerten (II, 12) der Strommesseinheit (ME2), sowie dem ersten (Uq1) und dem zweiten (Uq2) Spannungswert.
Abstract:
Zur Messung des Isolationswiderstands (Riso) eines Gleichspannungseingangs (2) eines laufenden transformatorlosen Wechselrichters (1),der an einem Wechselspannungsausgang (3)mit vorgegebenem Erdbezugeinen Wechselstrom ausgibt, und von an den Gleichspannungseingang (2) angeschlossenen Gleichspannungsquellen (6)gegenüber Erde wird ein periodisches Prüfspannungssignalmit einer geringeren Frequenz als derjenigen des Wechselstroms so gegenüber dem vorgegebenen Erdbezug des Wechselspannungsausgangs (3) generiert, dass es bei dem laufendem Wechselrichter (1) auf die Spannung am Gleichspannungseingang (2) aufmoduliert wird, und ein durch das Prüfspannungssignalhervorgerufener Erdstromwird erfasst.