A collecting and measuring method has corresponding a contacts group to a key of a computer keyboard; corresponding a contacts group state to a key state; corresponding a first keys group and a second keys group to a first power contacts group and a second power contacts group respectively; obtaining and storing a first values group and a second values group when the first keys group and the second keys group are closed respectively; calculating a difference value between the second and first values groups; dividing the difference value by the device frequency value to get a time value; and storing the time value. The time value is a conduct transition time value of a corresponding pole.

A sensor connecting unit includes a safety input for connecting with a sensor; a power supply that is controllable through a controllable power switch; and a first I/O processing unit and a second I/O processing unit being connected to each other through a reciprocal comparison communication channel. The first I/O processing unit and the second I/O processing unit are both connected through a measurement circuit to measure voltage, current or power between a reference input and the safety input, and connected to a safety bus. The first I/O processing unit informs the second I/O processing unit about switching off of the controllable power supply, the second I/O processing unit commands the first I/O processing unit to switch off the controllable power supply, and/or the second I/O processing unit measures an output of the controllable power switch to detect switching of the power switch.

The present invention provides a detecting method and a detecting apparatus for abnormal electrical connection in a main circuit of switchgear, wherein the detecting method comprises: acquiring a plurality of temperature rising values for measured areas of a plurality of electrical connectors in the main circuit of switchgear, the plurality of temperature rising values comprise a temperature rising value at a joint area of at least one of the electrical connectors; calculating a weighted average temperature of the plurality of temperature rising values; dividing each of the plurality of temperature rising values by the weighted average temperature to get normalized temperature rising values for the measured areas of the respective electrical connectors; comparing each of the normalized temperature rising values for the measured areas of the electrical connectors with a corresponding one of normalized threshold values for the measured areas of the respective electrical connectors. The detecting method of the present invention can accurately determine whether electrical connection of the measured areas of electrical connectors is abnormal under any electrical current.

The following steps are performed in order to test a tap changer (20) of a transformer (5; 6) which tap changer is designed to change a transmission ratio of the transformer (5; 6):

generating a test signal which is supplied to a winding (1-3; 10) of the transformer (5; 6) and to the tap changer (20).

Repeatedly actuating the tap changer (20) in order to change the transmission ratio with each actuation.

Determining a curve of an electrical measurement variable (I; I.sub.1; I.sub.2) of the transformer (5; 6) over time (t) respectively during the step of actuating the tap changer (20) depending on the test signal.

automatically illustrating the curves (41, 42) in a temporally-superimposed manner.

A collecting and measuring method has corresponding a contacts group to a key of a computer keyboard; corresponding a contacts group state to a key state; corresponding a first keys group and a second keys group to a first power contacts group and a second power contacts group respectively; obtaining and storing a first values group and a second values group when the first keys group and the second keys group are closed respectively; calculating a difference value between the second and first values groups; dividing the difference value by the device frequency value to get a time value; and storing the time value. The time value is a conduct transition time value of a corresponding pole.

A method for performing a low energy pulse testing in a power distribution network that causes contacts to close and then open in about one fundamental frequency cycle of current flow time and close on a voltage waveform that produces symmetrical fault current. The method includes energizing a magnetic actuator to move the actuator against the bias of a spring to move a movable contact towards a fixed contact. The method also includes de-energizing the actuator when the movable contact makes contact with the fixed contact so as to allow the spring to move the movable contact away from the fixed contact so that the amount of time that the current conducts is about one fundamental frequency cycle of the current, where energizing the magnetic actuator occurs when an applied voltage on the switch assembly is at a peak of the voltage wave so that the current is symmetric.

The present disclosure provides a detection system that includes a first sensing device configured for sensing an acoustic wave and an electromagnetic wave and generating a first combined signal and a signal processing device configured to determine the occurrence and properties of an electrical discharge.

A sensing arrangement for detection of electrical discharges in an electrical apparatus is described. The sensing arrangement includes an acoustic sensor and a signal enhancing structure with a funnel region. The acoustic sensor is positioned outside the funnel region on an apex side of the funnel region. An electrical switchgear is described. The electrical switchgear includes a sensing arrangement for detection of electrical discharges in an electrical apparatus. The sensing arrangement includes an acoustic sensor and a signal enhancing structure with a funnel region.

The present disclosure provides a detection system that includes a first sensing device configured for sensing an acoustic wave and an electromagnetic wave and generating a first combined signal and a signal processing device configured to determine the occurrence and properties of an electrical discharge.

A sensing arrangement for detection of electrical discharges in an electrical apparatus is described. The sensing arrangement includes an acoustic sensor and a signal enhancing structure with a funnel region. The acoustic sensor is positioned outside the funnel region on an apex side of the funnel region. An electrical switchgear is described. The electrical switchgear includes a sensing arrangement for detection of electrical discharges in an electrical apparatus. The sensing arrangement includes an acoustic sensor and a signal enhancing structure with a funnel region.