Bender GmbH & Co. KG

Methods and electric circuit arrangements for protecting metallic components in an electrolytic medium from corrosion due to direct-current (DC) stray current (Is) from a power supply system. The DC stray current may be jointly registered as a total sum current across all active conductors together with the protective conductor of the power supply system by a DC total differential-current sensor. Alternatively, a combined DC differential-current sensor is switchable by a switching device, a differential current being registered across all active conductors or the DC stray current being registered as a total differential current across all active conductors and the protective conductor. Alternatively, a differential current may be registered across all active conductors by a DC current sensor at the protective conductor and the DC stray current computed by forming differences of the differential current registered by the differential-current transformer and of the protective conductor registered by the DC current sensor.

Methods and devices for minimizing a possibly corroding DC protective-conductor current for a DC system grounded via a protective conductor designed as a foundation ground electrode with connected SK 1-operating equipment. Balancing includes feeding a balancing current to a casing of the class I operating equipment at a ground terminal via an output circuit between a fault-free active conductor and ground terminal, a balancing-current polarity and amplitude set such that the DC protective-conductor current is minimized in the foundation ground electrode. In contrast to DC balancing, DC compensation means a compensating current is fed to the casing at the ground terminal of the class I operating equipment via an output current between the faulty active conductor and the ground terminal. Regarding the polarity and the amplitude, the compensating current is such that the DC protective-conductor current is minimized in the foundation ground terminal. The balancing current and the compensating current are set via switching of power sources, resistors or a PWM signal.

A method and devices for testing and monitoring the continuity of a PEN conductor for a three-phase TN-C-S power supply system to which operating equipment is connected via a single or three phases. As intended by the invention, a voltage is measured for this purpose at a virtual star point set up according to the invention at operating equipment using three-phase machine terminals, and the measured star-point voltage is evaluated. Should the star-point voltage exceed a critical voltage, the operating equipment is disconnected. The invention therefore does not require a constructively difficult installation of a local reference ground. For operating equipment with single-phase machine terminals, a load voltage is measured in a first and a second load case along with a computation of a loop impedance from the voltage change and a residual-current change. The thus determined loop impedance value allows drawing a conclusion on whether a functional PEN conductor is present.

A method for determining an insulation resistance and a discharge capacitance to earth of an unearthed DC power supply system, wherein a linear differential equation is implemented with a measured voltage as a function of the measurement voltage and the grid voltage and with grid parameters formed from the shunts (RM), from the insulation resistances to be determined and from the discharge capacitances to be determined. N linear differential equations are used to implement a measured value equation system with the sample sequences and the grid parameters for k=1, 2 to N measurement times with the sampling period T.

The invention relates to a current return channel ( 20 ) and a method for the use of a residual current device ( 4 ) with a differential current sensor ( 8 ) in an ungrounded DC power supply system ( 2 ) in which the current return channel ( 20 ) is used. The current return channel ( 20 ) consists of an electronic circuit ( 22 ) which is coupled between each one of the active conductors (DC+, DC−) of the ungrounded power supply system ( 2 ) and ground (PE) via two terminals and is configured to be automatically activated temporarily when a low-resistance insulation fault ( 1 ) appears momentarily intermittently in order to form a fault circuit in which a current-limited fault current (I f ) flows, which triggers the residual current device ( 4 ).

An electric circuit arrangement and to a measuring method for the galvanically separate, AC/DC-sensitive residual-current measurement, the measuring method including registering a residual current (Id) by means of a measuring current transformer having a toroid and precisely one secondary winding; supplying power to the secondary winding and generating a time-modulated, binary measuring signal (V) having a corresponding dwell time (Th, T1) in a first state (S1) and a second state (S2) by means of a driver circuit having an oscillation circuit; evaluating the dwell times (Th, T1) by means of a computing unit and outputting a residual-current measured value (Im, I'm) by a data interface, wherein the driver circuit having the oscillation circuit forms an integral structural unit in the form of a driver module, which is supplied with a shared, unipolar operating voltage (Ub) by a power-supply device together with the computing unit.

The present disclosure relates to protective devices and methods for protection against electric shock in an AC, 3AC or DC power supply system, which has a main supply and additional power sources. In a first embodiment, a voltage measuring device is switched at each of the additional power sources. A signaling device disposed at the additional power sources signals when a voltage is exceeded by means of a disconnect signal should the measured voltage exceed a voltage threshold at the corresponding additional power source. A second embodiment comprises a residual current device disposed at each of the additional power sources and intended for identifying a corresponding residual differential current, and a measuring impedance switched at the additional power sources and intended for generating the residual differential current.

A method and insulation monitoring arrangement for insulation monitoring of an electric installation operated using a supply direct voltage and has a first insulation resistance between the positive active conductor and ground and a second insulation resistance between the negative active conductor and ground as well as a functional grounding between the negative active conductor and ground by a ground resistance. The method involves measuring a ground current, which flows in the path of the functional grounding, by means of a DC measuring device; measuring the supply direct voltage by means of a voltage measuring device; computing the first insulation resistance from the supply direct voltage divided by the ground current by means of a computing unit; the condition is valid during operation of the electric installation that the second insulation resistance being at least 100 times greater than the ground resistance.

A method for monitoring the continuity of a protective earth of a conductive charging system for electric vehicles configured according to standard IEC 61851-1 and having a charging station with having a CP generator for generating a CP control signal and a charging cable, which has the protective earth, active conductors, a CP signal conductor and a PP signal contact, the method including registering and evaluating a residual current flowing in the active conductors by an AC/DC sensitive residual-current monitoring module in combination with a measuring-current transformer. An interruption of the protective earth is determined in the residual current by registering and evaluating the CP control signal generated by the CP generator. A conductive charging system for electric vehicles based on standard IEC 61851-1 and implementing the method is also disclosed.

The invention relates an electric measuring arrangement ( 10 ) and to a measuring method both for monitoring a ground connection for an insulation monitoring device ( 4 ), which is connected to at least one active conductor (L 1 , L 2 ) of an ungrounded power supply system ( 2 ) and a ground terminal (PE) of an electric installation ( 3 ), with an active loop measurement device ( 20 ), which is connectable between a ground-connection clamp (E) of the insulation monitoring device ( 4 ) and the ground terminal (PE) and has an independent excitation voltage source (U gEKE ) for quantitatively determining a ground resistance (R EKE ) of the ground connection ( 6 ) between the insulation monitoring device ( 4 ) and the ground terminal (PE). Furthermore, the invention relates to an insulation monitoring device ( 30 ) having an electric measuring arrangement ( 10 ) according to the invention.