The purpose of the present invention is to provide a device monitoring technique having little restriction even on application to an already-existing device or facilitating monitoring even when a device to be monitored is in variable speed operation or under load variation. One of the representative device monitoring devices of the present invention monitors a device system using, as a power source, an AC electric motor driven by an inverter and is provided with a torque current estimation unit and a state estimation unit. The torque current estimation unit acquires information about AC currents of at least two phases and excitation current of the AC electric motor and calculates a torque current estimated value of the AC electric motor on the basis of the AC currents and the excitation current. The state estimation unit estimates the state of the device system from information including at least one of the feature amounts extracted from the torque current estimated value.

A current sensing device including: an insulating resin substrate; a current sensing element arranged in the resin substrate; a current wire provided via an insulating layer with respect to the current sensing element to flow a current through the current sensing element; a plurality of current vias connecting the current sensing element and the current wire through the insulating layer; and a voltage sensing via connected to the current sensing element to measure a voltage drop.

An electrical distribution system includes a distributor designed to distribute an electric current in an electrical installation, the distributor being configured to be connected to a distribution grid, to at least one secondary electrical power supply source and to a plurality of the electrical loads . An electronic control device is configured to manage power supply parameters of at least some of the electrical loads to reduce the electric current consumed and/or to manage operating parameters of at least some of the secondary electrical power supply sources in order to reduce the electric current delivered by these sources, so as to comply with a current threshold dictated by a protection element and/or by the distributor .

Provided are embodiments for determining solenoid plunger position by performing a method which includes generating, by a first signal circuit, a first signal based at least in part on a pull-in current value of a current applied to a solenoid coil of a solenoid. The method further includes generating, by a second signal circuit, a second signal by applying a time delay to the first signal. The method further includes comparing, by a comparator circuit, the first signal and the second signal to determine whether a plunger of the solenoid has moved within the solenoid from a first position to a second position. The method further includes, responsive to determining that the plunger of the solenoid has moved within the solenoid from the first position to the second position, reducing the current applied to the solenoid coil of the solenoid from the pull-in current value to a hold current value.

A device which can be used for current measurement is described hereinafter. According to one exemplary embodiment, the device comprises the following: a coil carrier extending along a longitudinal axis having a base body which in a central region has a section having reduced cross-sectional area, which is smaller than the cross-sectional area outside the central region, and a magnetic field probe having a ferromagnetic sensor strip, which is fastened to the coil carrier in the section having reduced cross-sectional area, and having a sensor coil which is wound around the coil carrier in the central region so that it encloses the sensor strip. The device also comprises a film which at least partially covers the section having reduced cross-sectional area. A secondary winding is wound around the coil carrier, wherein the secondary winding is wound around the film in the section having reduced cross-sectional area.

A current sensor according to the present invention includes a bus bar through which a measuring current flows; a nut with which the bus bar and an external terminal are brought into contact with and fastened to each other; a magnetic sensor capable of detecting a magnetic field generated when a current flows through the bus bar; a case member having a housing area in which the magnetic sensor is allowed to be housed, the case member sealing the bus bar and the nut inside; and a cover member provided over the housing area. The case member has an open part in which a portion of the nut is exposed. The open part is covered by an insulative protective member. Therefore, shavings generated when a bolt for fastening an external terminal is screwed into the nut are prevented from dropping to the outside of the current sensor.

A voltage comparator and an operation method thereof are provided. The voltage comparator includes an amplifying circuit, a reference current source, and a transient current source. A first input terminal and a second input terminal of the amplifying circuit respectively receive a first corresponding voltage corresponding to a target voltage and a reference voltage. The reference current source is coupled to the amplifying circuit to provide a reference current. The transient current source is coupled to the amplifying circuit to selectively provide a transient current. The transient current source detects a transition of a second corresponding voltage corresponding to the target voltage to dynamically adjust the transient current. Therefore, when a rapidly increasing voltage occurs in the target voltage, the transient current source may temporarily increase the current of the amplifying circuit, thereby accelerating the response speed of the amplifying circuit.

A current measuring device for detecting a current in an electric line includes: a housing; a fastening device arranged on the housing for fastening the housing to a supporting rail; and at least one magnetic field sensor. The housing has a first housing part and a second housing part which together form an accommodating device for accommodating an electric line between the first and second housing parts. The first and second housing parts are separable from one another in order to place an electric line onto the current measuring device and placeable onto one another in order to accommodate the electric line in the accommodating device between the first and second housing parts. The at least one magnetic field sensor detects a magnetic field on the electric line accommodated in the accommodating device.

A method and a photovoltaic inverter for determining the insulation resistance of a photovoltaic system relative to ground are provided. The voltage required for the measurement can be provided by an intermediate circuit in the form of an intermediate circuit voltage and a measuring device is designed to actuate an input short-circuit switch for short-circuiting a DC input with an AC disconnector open, as a result of which the intermediate circuit voltage can be applied to the DC input in the reverse direction. The measuring device is configured to record measured voltages with a switch of a voltage divider open and closed, and to determine the insulation resistance from the measured values of the two measured voltages recorded with the switch of the voltage divider open and closed.

A magneto-optical sensor for sensing a current flowing through a conductor includes a light source capable of providing a linearly-polarised optical beam, and a polarisation analyser configured to perform a differential measurement of two polarisation components of the linearly-polarised optical beam having travelled along an optical path arranged between the light source and the polarisation analyser. The optical path forms a closed trajectory around the conductor. The sensor comprises a cell containing an atomic gas arranged along the optical path.