Abstract: The invention relates to a method for insulation fault location in an IT power supply system, comprising the process steps: feeding of a test current, detecting of a test current portion in a branch of the IT power supply system and evaluating the detected test current portion. Furthermore, the invention relates to an insulation fault location for an IT power supply system having a test current generator for supplying a test current, having a test current sensor for detecting a test current portion in a branch of an IT power supply system and having an analyzing device for evaluating the detected test current portion. According to the invention, the insulation fault location system comprises a computing unit for adaptively determining a test current parameter of the test current depending on an electric system parameter of the IT power supply system.

Abstract: The invention relates to a method and to devices for extended insulation-fault search in an IT power supply system using a multifunctional test current, wherein, selectively and depending on the application, the test current functions as a voltage compensation current so as to compensate a voltage increase in an active conductor of the IT power supply system, as a tripping current so as to trip a residual current protection device arranged in a subsystem of the IT power supply system and/or as a leakage-capacitance compensation current so as to compensate a capacitive leakage current. The test current can fulfil more than one of the cited functions simultaneously.

Abstract: The invention relates to a method and to a device for shutting down an installation part provided with connected equipment in an ungrounded power supply system in case of an insulation fault in a direct-current circuit connected to the installation part to be shut down. The invention is based on first determining the insulation resistance of the IT power supply system and measuring the displacement direct voltage present in the IT power supply system and then determining by combined evaluation of the measured results if there is a risk of an disruptive influence on the operating behavior of the connected equipment due to the displacement direct voltage occurring during the duration of a predeterminable time interval. If a disruptive influence is to be expected, the installation part exhibiting the insulation fault is immediately shut down together with the direct-current circuit and the equipment connected thereto.

Abstract: An electrical protective device (20) and method are for selective disconnection of a subsystem (6a, 6b) in the event of a second fault in an ungrounded power supply system (2) with a main system (4) and at least one subsystem (6a, 6b), the subsystem (6a, 6b) having a differential current measuring device (12a, 12b) and a switching device (14a, 14b) for separating the subsystem (6a, 6b). The invention is based on generating and applying a measuring signal voltage (Um) between one or more phase(s) of the main system (4) or from a neutral point of the main system (4) against ground (9) using a resonant coupling circuit (22) that has a measuring signal generator (24) and a series resonant circuit (26) connected in series to the measuring signal generator (24), a resonant frequency (f0AK) of the series resonant circuit (26) being set to correspond to the measuring signal frequency.

Abstract: A method and device for impressing a measuring-signal voltage (U) on a power supply network in which a generator signal (Usig) is alternately sampled by two sample-and-hold elements (20, S1, S3), the sampled values are alternately allocated to a first pulse sequence (P1) and a second pulse sequence (P2), the pulse sequences (P1, P2) are separately inductively transmitted and the secondary-side measuring-signal voltage (U) is formed by adding the induced partial voltages (U1, U2) together.

Abstract: A method and a device for galvanically isolated, AC/DC sensitive current measurement including a control current transformer having a temporally changeable magnetic control flux which is not coupled to the magnetic flux in a measuring current transformer and forms a magnetic circuit in such a manner that a segment of the magnetic circuit of the measuring current transformer is formed as a shared segment with the magnetic circuit of the control current transformer so that the material forming the shared segment is permeated by the control flux and in connection with a nonlinear magnetic characteristic curve causes a change of the relative permeability in the material forming the segment and thus an induced partial voltage in the secondary winding.

Abstract: Methods and devices for insulation monitoring of an ungrounded IT power supply system having at least two phase conductors includes determining an insulation resistance separately for each phase conductor using a separate response value. In one embodiment of the invention, relevant current and voltage distributions are calculated. In another embodiment, a change time window is set within which a second response value is activated. In yet another embodiment, an option of shutting down/continuing operation of the IT power supply system is offered.

Abstract: A device and method is for insulation monitoring in a power supply system composed of a main system including a neutral point that is high-resistance grounded via a neutral-point resistance and, optionally, of at least one subsystem, wherein the main system and the subsystem each have a differential current measuring device for registering a differential current. The invention is based on feeding a measuring signal into the optionally branched HRG system via an active measuring method and registering the fault current driven by the measuring signal in the outgoing power feeds to be monitored by means of a differential current measurement and using the registered fault current in an evaluating device to determine the total insulation resistance of the power supply system and to determine the partial insulation resistances of the main system and potentially present subsystems. Furthermore, the insulation monitoring device can be employed for insulation fault location.

Abstract: The invention relates to an insulation fault locating system using branch-selective feeding and to a selective insulation monitoring system for a branched IT system composed of multiple subsystems. For insulation fault location, a differential current measuring device, a test signal generator and a blocking device are arranged in each subsystem. The insulation monitoring device additionally comprises a selective decoupling device arranged in each subsystem. Furthermore, the invention relates to a method for determining a cross impedance between two subsystems on the basis of the insulation monitoring system according to the invention.

Abstract: A method and a device for a galvanically isolated AC/DC-sensitive measurement of a residual current (?I), includes a component sensitive to magnetic fields which switches between at least two states in the course of oscillation. A magnetic field is formed in a sphere of action of the component sensitive to magnetic fields due to the residual current (?I) and an oscillator signal that switches between a state 1 and a state 2. As a function of the residual current-driven magnetic field, times of stay of the oscillator signal occurring in states 1 and 2 are determined and an output signal proportional to the residual current is obtained from the ratio of the times of stay.

Abstract: A method and device for monitoring a test interval for a residual current protective device includes measuring an operating time of the residual current protective device, triggering an alarm report if the measured operating time exceeds an operating time limit, and restarting the operating time measurement upon detection of a trigger process of the residual current protective device. In an embodiment of the invention, a time period is measured independent of the operating time of the residual current protective device.

Abstract: A method for monitoring and measuring an insulation resistance in ungrounded and grounded power supply systems includes the method steps of generating a periodic measuring signal, coupling in the measuring signal between active conductors of the power supply system to be monitored and ground, and detecting and evaluating measured values of the measuring signal. In one embodiment of the invention, the generated measuring signal is formed as a multi-frequency signal by the superposition of a finite number of harmonic oscillations with at least three harmonics. Alternatively, the multi-frequency signal can also be realized by means of a targeted, portioned construction of the signal shape in the time domain on the basis of a binary sequence optimization or by generating the measuring signal by means of the time-division multiplexing method.

Abstract: The invention relates to a method and a device (2) for galvanically isolated, AC/DC sensitive current measurement, comprising a measuring current transformer (4) having a primary winding (10) through which a current to be measured is flowing, a transformer coupling between the primary winding (10) and a secondary winding (14) via a shared magnetic flux (12) which forms a magnetic circuit having at least one segment (28) made from a material of a relative permeability, wherein in the secondary winding (14) a first partial voltage proportional to the change in time of the primary-side current is induced.

Abstract: A method and device for impressing a measuring-signal voltage (U) on a power supply network in which a generator signal (Usig) is alternately sampled by two sample-and-hold elements (20, S1, S3), the sampled values are alternately allocated to a first pulse sequence (P1) and a second pulse sequence (P2), the pulse sequences (P1, P2) are separately inductively transmitted and the secondary-side measuring-signal voltage (U) is formed by adding the induced partial voltages (U1, U2) together.

Abstract: A method and device for monitoring insulation and fault current in an electrical alternating current network. The differential current formed by vectorial addition is detected between at least two network conductors. Load-cut occurs when the differential current exceeds a specific threshold value. In order to increase safety and to protect human beings, the amount of alternating current contained in the differential current is detected as a first network variable, and the network alternating current between at least both network conductors and between at least one network conductor and an equipotential bonding conductor or a neutral conductor is detected as a second network variable.