A circuit breaker is disclosed for interrupting an electrical circuit when current limit values are exceeded. The circuit-breaker includes a current sensor for determining the electrical current flow and a control device. When current limit values are exceeded, the electrical circuit is interrupted. A first current limit value, when exceeded, results in an immediate interruption and a second current limit value, when exceeded, results in a time-delayed interruption, such that the second interruption time reduces as the current increases. Only one control element is included for setting a current limit value. The element defining the second current limit value is included for the time-delayed interruption of the electrical circuit. The other parameters are either set in a fixed manner and/or are related to the settable second current limit value.

A device comprises a circuit board, a Rogowski coil on the circuit board, persistent data storage on the circuit board, and a control circuit on the circuit board for collecting values representing current sensed by the coil, and storing the values in the persistent memory.

The present application relates to a clamp meter and a clamp probe that can be matched for use with the clamp meter. The clamp meter comprises a main meter body having an interfacing connector and one or more clamp probes, wherein each of the clamp probes is detachably connectable to the interfacing connector of the main meter body. Each of the clamp probes has a converting unit that converts a signal measured by the clamp probe to an output measurement signal within a predetermined measurement range of the main meter body, and each of the clamp probes has an identity indicator readable by the main meter body. As the clamp meter according to the present application can be matched with a plurality of clamp probes having different measurement ranges, a user only needs to purchase one main meter body and one or more clamp probes of different models to meet various measuring needs. This can enhance the flexibility and extendibility of the usage of a clamp meter, as well as reduce the user's financial burden.

The present application relates to a clamp meter and a clamp probe that can be matched for use with the clamp meter. The clamp meter comprises a main meter body having an interfacing connector and one or more clamp probes, wherein each of the clamp probes is detachably connectable to the interfacing connector of the main meter body. Each of the clamp probes has a converting unit that converts a signal measured by the clamp probe to an output measurement signal within a predetermined measurement range of the main meter body, and each of the clamp probes has an identity indicator readable by the main meter body. As the clamp meter according to the present application can be matched with a plurality of clamp probes having different measurement ranges, a user only needs to purchase one main meter body and one or more clamp probes of different models to meet various measuring needs. This can enhance the flexibility and extendibility of the usage of a clamp meter, as well as reduce the user's financial burden.

A Rogowski coil is used for determining the magnitude of the electrical current of a conductor of a low-voltage AC circuit, which outputs an analogue voltage which is equivalent to the magnitude of the electrical current of the conductor. The Rogowski coil is connected to an analogue integrator, which is followed by an analogue-digital converter, which converts the integrated analogue voltage into a digital signal which is further processed by a microprocessor in such a way that the phase shift generated by the Rogowski coil and the components connected downstream of the Rogowski coil is compensated such that there are in-phase current values for the detection of error situations in order to protect the low-voltage AC circuit, in particular for a low-voltage power switch or an arc fault detection unit.

Magnetic saturation detectors for power converters are presented herein. An energy transfer element has an input power winding wrapped around a center post. Single or multiple transverse windings are positioned perpendicular to the input power winding and coupled to receive a transverse current that provides a transverse magnetic flux density within the energy transfer element. The transverse magnetic flux density produces a transverse voltage waveform. A voltage detection circuit is configured to receive the transverse voltage waveform and detect a change in the sign of the slope of the transverse voltage waveform. The change in the sign of the slope indicates magnetic saturation. The voltage detection circuit is configured to detect an occurrence of an extremum in the transverse voltage waveform. The extremum indicates the change in the sign of the slope.

A current measurement system is configured to measure an alternating-current (AC) current flowing through a conductor. The AC current has a frequency within a measurement range. The system includes a current sensor and a shunt resistor. The current sensor includes a measurement coil configured to be magnetically coupled to the conductor. The shunt resistor has both ends electrically connected to both ends of the measurement coil, respectively. An output voltage across the both ends of the shunt resistor is saturated at a saturation point in a saturation frequency of the frequency of the AC current. An upper limit value of the measurement range including the frequency is higher than a fundamental frequency of the AC current. The saturation frequency is higher than or equal to the upper limit value. The current measurement system improves sensitivity to frequency components higher than the fundamental frequency of the AC current.

A current measurement system is configured to measure an alternating-current (AC) current flowing through a conductor. The AC current has a frequency within a measurement range. The system includes a current sensor and a shunt resistor. The current sensor includes a measurement coil configured to be magnetically coupled to the conductor. The shunt resistor has both ends electrically connected to both ends of the measurement coil, respectively. An output voltage across the both ends of the shunt resistor is saturated at a saturation point in a saturation frequency of the frequency of the AC current. An upper limit value of the measurement range including the frequency is higher than a fundamental frequency of the AC current. The saturation frequency is higher than or equal to the upper limit value. The current measurement system improves sensitivity to frequency components higher than the fundamental frequency of the AC current.

A current measuring device having a probe body with an elongated portion extending outward from a rearward main body portion to a hook-shaped forward end, the hook-shaped end useful for isolating a conductor under test, a slide closure member adapted to slide longitudinally forward from a rearward open position to a forward closed position, the closed position useful to capture the conductor under test within a space encircled by the combination of the hook-shaped end, the closed slide closure member, and the rearward main body, with the space encircled including a current sensing zone, and circuitry adapted for detecting a magnetic flux generated by an electric current passing through the conductor under test positioned within the current sensing zone. A release button for moving the slide closure member serves as a switch to turn on the meter/tester/device when the jaw/slide closure member is opened.

A centralized voltage control device connected, via a communication network, to local voltage control devices connected to voltage control apparatuses, including: a transmission and reception unit receiving the number of times a tap position is changed per fixed time of the voltage control apparatus from the local voltage control device; a dead-zone-width updating unit increasing a dead zone width when the number of times a tap position is changed in a voltage control apparatus of a transformer type is a threshold or larger; and a voltage-upper-and-lower-limit-value determining unit determining the voltage upper limit value and the voltage lower limit value for each local voltage control device and issuing a command regarding these values to each local voltage control device, and determining the voltage upper limit value and the voltage lower limit value of the voltage control apparatus of a transformer type on the basis of the dead zone width.