954 results about "Surge voltage" patented technology

A surge protection element for a conventional cable connector includes a printed circuit board preferably shaped as two concentric rings connected by two spokes. The outer ring is electrically connected to the grounded portion of the cable connector body. A printed circuit trace on one of the spokes is separated from a printed circuit trace on the inner ring by a spark gap. If a high voltage surge is carried by the coaxial cable transmission line, a spark is formed in the gap. As a consequence, the high voltage surge is transferred to the surge protection element which in turn conducts the electricity to the grounded body of the connector.

A decision circuit (10) monitors a main current flowing in an IGBT (1), and when operation of the IGBT (1) enters an overcurrent state and the control voltage applied to the control terminal (G) of the IGBT (1) is equal to or larger than the threshold voltage, it determines that the IGBT (1) is in the overcurrent state and places the IGBT (1) in an OFF state, and also outputs the result of the determination as an output signal to an external microcomputer from an error output terminal (9). Receiving this output signal, the microcomputer immediately fixes driving signals for the IGBT (1) and another IGBTs at an OFF signal level to disconnect these IGBTs, thus preventing the main current of the IGBT (1) from increasing to a still larger overcurrent to protect the IGBT (1). Generation of a turn-off surge voltage is suppressed in the overcurrent state by detecting the overcurrent state of the power transistor by earlier timing.

The DC-DC converter connects a first and a second switching circuit for converting power mutually between direct current and alternating current respectively to a first DC power source and a second DC power source and has a transformer between the AC terminals thereof. Here, between the AC terminals of the second switching circuit and the negative pole terminal of the DC power source, a voltage clamp circuit composed of a series unit of switching devices with a reverse parallel diode and a clamp condenser is connected. An isolated bidirectional DC-DC converter which prevents a reduction in a circulating current at time of buck and an occurrence of a surge voltage at time of voltage boost and realizes highly efficiency, low noise, and miniaturization is provided.

A trailing edge of a control signal of a transistor controller for controlling an output transistor is detected by an edge detector of a clamp controlling circuit. A surge voltage from a back electromotive voltage induced in an inductance L1 is absorbed from the output transistor, only for a given period immediately after the solenoid is turned off, by turning a switching transistor into an on-state by a timer to force a clamping circuit into conduction. At a normal operation, since the clamping circuit is cut off from an output terminal, the clamping voltage can be set in a manner to reduce to a normal voltage in an IGN-line. Therefore, a peak power value of a power loss caused by the surge voltage at the output transistor can be reduced, whereby generation of heat at the output transistor can be reduced. Therefore, the chip size of the power IC can be reduced.

The apparatus for partial discharge detection of turn-to-turn insulation in motor has a surge generator for generating a surge voltage to the windings of the motor by applying a pulse voltage, and a partial discharge current detector for detecting partial discharge currents between the winding turns of the motor. The surge generator generates in and between the windings of the motor the surge voltage that has the rise time and fall time corresponding to the rise time of the surge voltage observed at the motor terminal when the motor is driven by an inverter, and that is repeated at a frequency of 50 Hz to 20 kHz.

A control device includes a capacitor disposed between P-N lines and constituting a snubber circuit, and a voltage detection resistor for detecting a voltage between the P-N lines by dividing resistances to detect surge voltages of transistors, in which gate control signals are provided from drivers to the transistors through gate resistance variable devices, respectively. The gate resistance variable devices include variable resistors, respectively, and the resistance values of the variable resistors are controlled based on variable resistor control signals provided from a detected voltage monitoring device, respectively.

The present invention provides a switching power supply unit capable of suppressing a surge voltage generated in a rectifier element more effectively. A first resonance circuit is constructed by capacitors in a surge voltage suppressing circuit and an inductor, and resonance time of the first resonance circuit is set to be longer than recovery time of a diode in a rectifier circuit. According to at least one of a DC input voltage and an output current, either a first bridge circuit or a second bridge circuit is selectively allowed to perform switching operation. At the time of forward-direction operation, the first resonance circuit is formed by the capacitors in the surge voltage circuit and the inductor on the high voltage side. At the time of reverse-direction operation, a second resonance circuit is formed by the capacitors and an inductor on the low voltage side.

A device to protect against a surge voltage includes a body having a hexahedron shape and filled with a varistor material, a pair of input signal electrodes attached to a first side surface of the body along upward and downward directions, a pair of output signal electrodes attached to a second side surface of the body that faces the first side surface of the body in the upward and downward directions, a ground electrode attached to an upper surface of the body, at least one pair of signal connection electrode plates to connect the input signal electrodes and the output signal electrodes, and a ground plate to be connected to the ground electrode. Thus, the device can protect an electronic circuit from a surge voltage and match an impedance of a transmission line.

A first condenser is connected between output terminals of a rectifier circuit which receives an AC power as an input, and a three phase inverter is connected in parallel with respect to the first condenser, and output of the three phase inverter is supplied to a motor, and a second condenser is connected in parallel to the input side of the three phase inverter, and a current detector is connected between the first condenser and the second condenser, and a third condenser is connected in parallel to the first condenser at a position slightly power side with respect to the current detector, and the capacitance of the second condenser is determined as small as possible within the range in which power devices are not destroyed by surge voltage due to switching, therefore, ringing is suppressed, and taking of current is performed rapidly and with high accuracy.

Disclosed herein is a hybrid type sensor for detecting high frequency partial discharge which can detect high frequency partial discharge at a high signal-to-noise ratio without being influenced by power noise and surrounding noise, and guarantee the safety of a test when breakdown occurs. The sensor forms two or three signal paths with different impedances wherein a low frequency power signal is bypassed to ground through a first path, and a high frequency partial discharge current is allowed to flow through a second path and is detected as a resistance component through a resistor. Further, a surge voltage input to the sensor due to breakdown is input to the ground through a third path.

The present invention relates to structures and methods that reduce ESD damage to electronic devices. In an embodiment, the structure is a parallel plate dissipative capacitor formed by sandwiching a dissipative dielectric layer between two conductive layers in series to the electronic device. The dissipative dielectric layer includes a nonconductive dielectric doped with a voltage dependent resistive material that defines a conductive threshold voltage. The structure functions as a voltage dependent resistor in response to an applied voltage such as an ESD surge voltage exceeding the defined conductive threshold voltage and dissipates the applied voltage into thermal energy before it can reach the electronic device and cause damage. The dissipative dielectric layer restores to a dielectric and the structure functions as a capacitor when the excess voltage is depleted that is drops below the defined conductive threshold voltage. In another embodiment, the structure is a parallel plate dissipative capacitors in series that enhances ESD mitigation through a capacitive voltage divider structure. The structures can be used in EMI/RFI shielding applications.

The invention relates to a novel direct-current converter valve test unit and a test method thereof. The test unit comprises an industrial computer, a surge voltage unit, a low-voltage triggering test unit, an impedance tester LCR, a 24V power supply, a valve voltage-current waveform acquisition system, a keyboard mouse, a display unit and an over-voltage and over-current protection unit. After a test is performed, the display unit can display each testing voltage-current waveform, and if a test is failed, the novel direct-current converter valve test unit is convenient to analyze and search problems.

The invention relates to a traveling wave analysis and recognition method for distinguishing lightning shielding failure from lightning counterattack of direct current transmission line. The lightning shielding failure of line is that lightning avoids the lightning shield line and directly strokes on the transmission line, while lightning counterattack of line is that lightning directly strokes on the lightning shield line or the tower. Because the earth resistance of tower exists, the potential on tower top suddenly increases and causes insulation flashover. The electromagnetic transient component generation mechanism of the high voltage direct current transmission line and the propagation path of lightning electromagnetic transient of the line in the lightning shielding failure are different from those in the lightning counterattack, the size and polarity of the initial surge voltage and the second surge voltage of the voltage transient signal exist significant difference. The traveling wave analysis and recognition method of the invention analyzes zero mode voltage using wavelet and distinguishes the lightning shielding failure and lightning counterattack failure according to the size and polarity of the initial surge voltage and the second surge voltage of the zero mode voltage in the traveling wave analysis and high-speed acquisition system of the protection zone. A lot of simulation results show that the method is reliable and effect. The physical concept of the invention is visible and clear, the method is easy to achieve and wide to use in the direct current system protector, also provides accurate initial data for researching lightning characteristics, analyzing lightning accident, discussing lightning protection countermeasure of transmission line and designing insulation coordination in the power system.

A semiconductor device equally turns on the parasitic bipolar transistors in the finger portions of the finger form source and drain electrodes when a surge voltage is applied, even with the P+ type contact layer surrounding the N+ type source layers and the N+ type drain layers connected to the finger form source and drain electrodes. A P+ type contact layer surrounds N+ type source layers and N+ type drain layers. Metal silicide layers are formed on the N+ type source layers, the N+ type drain layers, and a portion of the P+ type contact layer. Finger form source electrodes, finger form drain electrodes, and a P+ type contact electrode surrounding these finger form electrodes are formed, being connected to the metal silicide layers respectively through contact holes formed in an interlayer insulation film deposited on the metal silicide layers.

A thin film circuit substrate is provided with a voice-output-section driving section, formed of a thin film layer on an insulative substrate, for driving a voice output section. An antisurge section, provided on a wiring between the voice-output-section driving section and an output terminal section thereof, includes an antisurge element. When a surge voltage is applied to the wiring, the antisurge element, monolithically formed on the thin film circuit substrate, connects the wiring to the ground so as to pass a current (surge current), generated by the surge voltage applied to the wiring, to the ground. This makes it possible to provide a thin film circuit substrate which is monolithically provided with a function which can protect a circuit section when a voltage exceeding a predetermined range is applied to the wiring linking the circuit section with an input terminal section or an output terminal section.

The invention discloses a preceding-stage EMI filtering protective circuit of a driving power source. The preceding-stage EMI filtering protective circuit of the driving power source comprises a fuse, a temperature-sensitive resistor, a surge protection circuit, a differential mode interference suppression circuit, a common mode interference suppression circuit and the like. According to the preceding-stage EMI filtering protective circuit of the driving power source, a multi-stage filtering structure is used for carrying out effective filtration and removal on electromagnetic interference signals entering from a power grid, three voltage dependent resistors with different discharge voltage values are used for carrying out discharge protection on surge voltage, and the fuse and the temperature-sensitive resistor are arranged close to a connection port, can carry out disconnection protection when the overcurrent occurs, and achieves the effect of soft start on the whole driving power source. The preceding-stage EMI filtering protective circuit of the driving power source has the advantages of being simple in circuit, small in size, low in cost, good in reliability, high in inserting loss and the like.

A semiconductor circuit system has first, second, and third external terminals electrically separated from each other. The first external terminal is configured to receive a first power supply voltage in a normal operation. A protection circuit section is provided in the circuit system and includes a rectifier to allow a surge current to pass therethrough. The rectifier has a current passage connected between a specific terminal connected to a protection target and the third external terminal. The protection circuit section further includes a first PMOS transistor configured to trigger the rectifier, based on a surge voltage inputted into the second external terminal. The first PMOS transistor has a current passage connected between the second external terminal and a base of the NPN transistor. The first PMOS transistor has a gate connected to the first external terminal.

In a semiconductor device, a surge voltage is lowered on turning OFF of a switching element, and output current is reduced on turning ON of the switching element in a non-saturated condition to achieve a reduced amount of self-heating. The semiconductor device can comprise a semiconductor switching element, an overvoltage protection circuit, and a resistance circuit to transmit a control signal for turning the switching element ON and OFF to a control terminal of the switching element. The semiconductor device can further comprise a voltage detecting switch that receives a signal corresponding to a voltage appearing at the output terminal of the switching element on turning OFF of the switching element, and a gate resistor change-over switch that operates according to a voltage of a timing capacitor connected to the output side of the voltage detecting switch to increase a resistance value of the resistance circuit.

A surge voltage detection circuit compares a stipulated voltage V_S with the drain voltage of a switching element, the drain voltage being applied by a smoothing capacitor. The comparison result is supplied to a switching control circuit. If the drain voltage of the switching element is higher than the stipulated voltage V_S, the switching control circuit inhibits the operation of the switching element. As a result, no switching operation is started, and the drain voltage of the switching element does not exceed the breakdown voltage of the element.

A device for protecting an electrical system against surge voltages, comprising one or more protection components provided with means for connecting same with said system and means for disconnecting said component from said system, characterised in that it comprises arc-breaking means for preventing the generation of electric arcs between the disconnection means and the connection means when the disconnection means is in an open state, wherein said arc-breaking means consist of an insulating flap capable of moving within the gap and comprising a central portion to be positioned between the disconnection and connection means, and side portions shaped in such a way as to prevent the electric arc from bypassing the arc-breaking means. Electrical surge voltage protection devices are also described.