147results about How to "Act as a current limiter" patented technology

The invention relates to a grounding detecting method of a power supply system of a train. A passive low-resistance midpoint grounding detecting mode is adopted and is characterized in that a grounding voltage sensor is connected in parallel on an anode line near a first resistor R1 and a second resistor R2 which are connected in series on a no-load of an original power supply system; the grounding voltage sensor is independently grounded; a middle tap is led out between the first resistor R1 and the second resistor R2 which are connected in series on the no-load of the power supply system; at least one auxiliary resistor R3 is connected between the middle tap and an independent groundling line of the grounding voltage sensor; the auxiliary resistor R3 is respectively connected with the middle tap led out between the first resistor R1 and the second resistor R2 of the no-load of the power supply system and the grounding line of the grounding voltage sensor so that when the direct current side of the power supply system of the train is grounded or when electric insulating level is decreased, a positive line or a negative line of the power supply system is equivalent to connect with a resistor relative to the ground. By adopting the invention, the detection reliability of the grounding detection of the power supply system of the train is improved, and phenomena of false operation are reduced.

The invention discloses a current-limiting type fast reclosing DC circuit breaker topology structure and control method. The structure comprises a current carrying circuit, a current limiting circuit,a current converting circuit, a current cutting circuit and a freewheeling circuit. The current-carrying circuit comprises a mechanical switch and an auxiliary current-converting switch which are connected in series in turn. The current limiting circuit is serially connected with both sides of the current carrying circuit, and the current converting circuit is connected with the current carryingcircuit in parallel. The current converting circuit comprises an upper bridge arm and a lower bridge arm composed of two diodes. The current cutting circuit is serially connected between the upper bridge arm and the lower bridge arm, and the current freewheeling circuit is serially connected between the lower bridge arm of the current converting circuit and the earth. The cut-off circuit comprisesa power electronic branch and a lightning arrester branch which are connected in series by a plurality of sub-modules. The lightning arrester branch is connected in parallel with the power electronicbranch. The invention has the beneficial effects of effectively solving the problem of high cost caused by two sets of through current branches, limiting the rise rate and peak value of the fault current, greatly accelerating the energy release speed of the fault-side inductor, and facilitating rapid reclosing.

The invention relates to an automatic transfer switching equipment of an instant parallel arrangement, which aims at solving the problem that the existing conversion process of an automatic change-over switch can not realize the aim of uninterruptible power. The electric appliance comprises a latch plate, an oscillating deck A, an oscillating deck B, rollers, a main shaft, a main support, a damper, an electromagnet, a connecting bar which is connected on a movable iron core of the electromagnet and is provided with a slotted hole, a base, a movable contact A, a movable contact B, a fixed contact A and a fixed contact B. Both of the movable contacts are respectively connected to two separate power supplies, both of the fixed contacts are connected on a load terminal, the bottoms of the oscillating deck A and the oscillating deck B are respectively connected with connection blocks which are arranged on the movable iron core on the electromagnet which is arranged on the adjacent side, when the rollers on the two oscillating decks are positioned on the high position of the cam which is arranged on the latch plate, the two movable contacts are instantly and simultaneously connected with the fixing contacts (instantly connected in parallel), which guarantees that at least one of the two power circuits is connected with the loading at any time and the loading can not be interrupted during the changing over process of the switch and realizes the closed switching over of the power source.

The invention relates to a flexible direct-current grid fault current limiter with quick recovery capacity. The flexible direct-current grid fault current limiter with the quick recovery capacity is characterized in that the current limiter comprises four diode sets D1-D4 connected in series, a square iron core, a winding L1 and a winding L2, wherein the four diode sets D1-D4 connected in series are used as four bridge arms to form a single-phase rectifier bridge; the winding L1 is wound around one side of the square iron core, connected with a direct-current bias power supply Udc1 in series, and then connected between a common cathode point P of the diode sets D1 and D3 and a common anode point N of the diode sets D2 and D4; the other side of the square iron core is wound with the winding L2; the winding L2 is connected to the two ends of a direct current power supply Udc2 after being connected with a direct-current switch S in series; the winding direction of the windings L1 and L2 needs to ensure that generated magnetic field directions are the same. The flexible direct-current grid fault current limiter with the quick recovery capacity can realize quick response after faults occur and cooperate with a direct current breaker efficiently, and can also realize quick recovery after faults are removed.

The invention discloses a modular DC energy consumption device. The device comprises at least two voltage-sharing energy consumption modules, wherein the at least two voltage-sharing energy consumption modules are connected in series in the same direction, each voltage-sharing energy consumption module comprises a DC capacitor, a current-limiting unit, an energy consumption branch and a bypass switch, the DC capacitor and the current-limiting unit are connected in series to form a first series unit, an initial end and a tail end of the first series unit both are used as an initial end and a tail end of the voltage-sharing energy consumption module, the energy consumption branch is connected in parallel with two ends of the DC capacitor, and the bypass switch is connected in parallel with the first series unit. The invention also discloses a control method of the modular DC energy consumption device. When a voltage of a DC circuit is raised, the withdraw of an energy consumption resistor is controlled by controlling a first power semiconductor device so as to stabilize a DC voltage; and when a fault occurs in the voltage-sharing energy consumption module or a DC circuit is circuit-shorted, a discharging current of the capacitor is limited by the current-limiting unit. The device is high in cost performance and high in reliability and is easy to implement.

The invention discloses an OLED (organic light-emitting diode) lighting substrate and a manufacture method thereof. The OLED lightening substrate comprises a substrate, wherein a positive electrode, an organic functional layer and a negative electrode are sequentially arranged on the substrate; a resistance layer is arranged between the substrate and the positive electrode, and the resistance layer is divided into multiple block-shaped resistors; the positive electrode is divided into multiple sub positive electrodes, and each sub positive electrode is connected with a block-shaped resistor in series; and the multiple block-shaped resistors are connected together through interconnection lines. The OLED lighting substrate and the manufacture method thereof disclosed by the invention have the characteristics that: a series-connection resistance layer is arranged between a power supply and the positive electrode, thus a current limitation action is achieved; and a whole large-area positive electrode is divided into smaller-area sub positive electrodes, so that the intensity of the gathered current generated by the positive electrodes isolated by resistors is weakened, the current gathering effect is weakened and short-circuit probability of the negative and positive electrodes is reduced, thus the problems that the electrode is easy to burn out and the light emitting is nonuniform are solved.

The invention relates to a novel bridge type solid-state fault current limiter and a using method thereof. The novel bridge type solid-state fault current limiter comprises a single-phase rectifier bridge unit, a current limiting unit and a circuit break unit. The single-phase rectifier bridge unit comprises thyristor valves T and diodes D. The two ends of the current limiting unit are connected to the single-phase rectifier bridge unit. One end of the current limiting unit is positioned between a cathode of the thyristor valve T1 of the single-phase rectifier bridge unit and a cathode of the diode D1, and the other end of the current limiting unit is positioned between an anode of the thyristor valve T4 of the single-phase rectifier bridge unit and an anode of the diode D2. The single-phase rectifier bridge unit and the current limiting unit together form a single-phase fault current limiter. The circuit break unit is in parallel connection with the single-phase fault current limiter. The novel bridge type solid-state fault current limiter can be automatically and quickly accessed to an electric system if the system has a short circuit fault, so the first peak value of a short circuit current is effectively limited, a current limiting effect is achieved and the requirement of fault identification is reduced. Moreover, the novel bridge type solid-state fault current limiter is simple in overall structure and low in cost.

The invention relates to the technical field of secondary batteries, in particular to a balance method of the battery capacity of a secondary battery group, characterized in that a balance resistor network is adopted, and the balance resistor network is formed by using same resistors to connect the battery nodes in the secondary battery group and can adopt a common connection mode, a star connection mode or a triangular connection mode. The invention effectively balances the battery capacity of the secondary battery group, prolongs the service life of the battery group and decreases the replacement cost of storage batteries.

A sectionalized electrical heating regeneration device for a diesel particulate filter is composed of an engine exhaust and intake tube, an intake reducer large end, a packaging shell and a gas outlet reducer large end in a connected mode in sequence. A supporting disk is composed of a circular ring and a plurality of spokes arranged in the radial direction, a rotary baffle is fixed to the spokes of the supporting disk through a bearing, a shaft of a stepping motor is connected with a shaft sleeve of the rotary baffle through a key, and resistance wires are arranged in a channel of the diesel particulate filter. When regeneration needs to be carried out, the stepping motor drives the rotary baffle to rotate to a regeneration area so that the flow of the regeneration area is immediately reduced, and the resistance wires are powered on at the same time so that the purpose of regeneration is achieved. The sectionalized electrical heating regeneration device for the diesel particulate filter is simple in structure and capable of running for a long time, and has the advantages of being convenient to disassemble and assemble, reliable in performance and the like.

The invention discloses a bridge type DC energy consumption device which comprises at least two bridge type energy consumption modules. Each bridge type energy consumption module is formed by connecting a DC capacitor, a first energy consumption branch and a second energy consumption branch in parallel. The first energy consumption branch is formed by connecting a first power semiconductor deviceand a first energy consumption resistor in series, and a connection point of the two is led out as a first lead-out end. The second energy consumption branch is formed by serially connecting a secondpower semiconductor device and a second energy consumption resistor, and a connecting point of the two is led out as a second lead-out end. The at least two bridge type energy consumption modules areconnected in series in the same direction to form the bridge type DC energy consumption device. The invention further discloses a control method based on the bridge type DC energy consumption device.When the voltage of a DC line rises, the power semiconductor device is controlled to control the on-off of the energy consumption resistor so as to stabilize the direct-current voltage. When the DC line is short-circuited, the first energy consumption resistor and the second energy consumption resistor are connected in series to limit the direct current capacitance current. The device is high in cost performance, high in reliability and easy to implement.

The invention provides a CC pin circuit of USB Type-C. In the Type-C interface circuit, a high-voltage NMOS is introduced for voltage isolation, and a first low-voltage region is generated. A pull-upresistor circuit, a CC connection detection circuit, a PD communication circuit and the like are placed in the first low-voltage region to realize high-voltage protection. The pull-down resistor circuit is directly connected to the CC pin, so that when the Type-C interface is in a Dead Battery state in a DRP or SNK mode, the CC connection can be normally realized by accessing the SRC or other DRPs(Data Redundancy Protocol). And a resistor in the pull-down resistor circuit is divided into a first resistor and a second resistor which are connected in series, and voltage clamping is performed ata middle series node to generate a second low-voltage region. And an enable control switch of the pull-down resistor circuit and the second resistor are placed in the second low-voltage region to realize high-voltage protection. The first resistor is placed in a high-voltage area and plays a role in current limiting when the voltage clamping circuit works. The withstand voltage design method andthe circuit structure can be applied to Type-of all modes. And in the C interface circuit, the voltage withstanding problem of the CC pin is solved.

The invention relates to a sprinkle-nozzle, in particular to an impact-typed elastic self-dredge water coating sprinkle-nozzle, which is composed of a stylet, a nozzle, a semi-spherical cavity, a sprinkle-nozzle body, a liquid cylinder, a liquid hole, a spring, a light plastic ball, a sealing ring, a sealing bowl, a spraying seat and an outlet. The liquid cylinder is a cylindrical shape; the upper end and the lower end of the liquid cylinder are provided with the liquid holes; the central position at the lower end of the liquid cylinder is provided with a hole where the stylet can freely pass; the lower end of the stylet is provided with a disc; the spring is sheathed on the stylet; the light plastic ball is arranged in a space between the top end of spraying seat inside the sprinkle-nozzle body and the disc which is arranged at the lower end of the stylet. Under the action of the impacting force of coating liquid, the disc which is arranged at the lower end of the stylet is repeatedly impacted by the light plastic ball, the stylet reciprocates, and the thickened and hardened coating at the outlet is removed by a thread on the stylet, thus always keeping the smoothness of the outlet.

The invention provides a level shifter and a display device. The level shifter comprises a logic setting unit, a control unit, a first field-effect transistor, a second field-effect transistor, and an overcurrent protection module, wherein an input end of the logic setting unit inputs an initial signal, and an output end of the logic setting unit is connected with an input end of the control unit; the control unit is provided with a first output end and a second output end; a gate of the first field-effect transistor is connected with the first output end, and a high-level voltage is input to a source of the first field-effect transistor; a gate of the second field-effect transistor is connected with the second output end, and a low-level voltage is input to a source of the second field-effect transistor; drains of the first field-effect transistor and the second field-effect transistor are both connected with a main output end; and the overcurrent protection module is used for reducing the resistance of the level shifter at a starting stage of the level shifter, and increasing the resistance of the level shifter at a working stage of the level shifter. The level shifter and the display device provided by the invention have the advantages that voltage rise time can be shortened, and false triggering and screen melting can be avoided.

The invention provides a thyristor-based solid state fault current limiter. The solid state fault current limiter comprises three single-phase current limiters; each single-phase current limiter comprises a main circuit and a breaker; the main circuit comprises a first current-limiting reactor and a second current-limiting reactor that are in series connection, and a first thyristor and a second thyristor; the solid state fault current limiter is serially connected to a power transmission line; when the circuit has no faults, the current limiter works normally, the thyristor is switched on constantly, and the equivalent impedance of the current limiter is basically 0; when the circuit has faults, the current limiter enters a current-limiting working state automatically without delay to limit a first peak value of the short circuit current; then the two current-limiting reactors are fully connected to the circuit by removing the trigger signal of the thyristor to limit a steady-state value of the short circuit current. The thyristor-based solid state fault current limiter has low demand on the fault identification speed without requiring to add a bypass current-limiting reactor, so that the thyristor-based solid state fault current limiter is simple in structure, high in reliability, and convenient in engineering applications.

The invention provides a monitoring system of a fault current limiter. The system comprises a voltage limiter MOV, a reactor L, a capacitor C, a relay coil T0, a relay switch T1 and a temperature monitoring system, wherein the voltage limiter MOV and the relay switch T1 are connected in series and then connected to the two ends of the capacitor C in parallel; the parallel output end of the capacitor C is connected with one end of the reactor L and the other end of the reactor L is connected with the relay coil T0; the temperature monitoring system comprises a wireless temperature sensor, a wireless transmission unit, an intelligent temperature monitor and a background monitoring center; the wireless temperature sensor is connected with the voltage limiter MOV. The monitoring system of the fault current limiter achieves a triple protective function for the current limiter by simple structural system settings.

The invention discloses a resistance-capacitance voltage-divided zero-sequence voltage sensor, comprising an A-phase resistance-capacitance voltage divider, a B-phase resistance-capacitance voltage divider, a C-phase resistance-capacitance voltage divider, and a secondary adjustment protection unit, wherein the A-phase resistance-capacitance voltage divider consists of an A-phase high-voltage armimpeder and an A-phase low-voltage arm impeder connected in series, the B-phase resistance-capacitance voltage divider consists of a B-phase high-voltage arm impeder and a B-phase low-voltage arm impeder connected in series, the C-phase resistance-capacitance voltage divider consists of an A-phase high-voltage arm impeder and a C-phase low-voltage arm impeder connected in series, the secondary adjustment protection unit consists of an adjustment resistor, an adjustment capacitor, a discharge tube and a varistor connected in parallel, each phase of low-voltage arm impeder and the secondary adjustment protection unit are connected in parallel to form a low-voltage voltage-dividing impeder, and the low-voltage voltage-dividing impeder outputs zero-sequence voltage values at two ends. The resistance-capacitance voltage-divided zero-sequence voltage sensor can output a voltage linearly proportional to a zero-sequence voltage, is used for monitoring the faults such as voltage imbalance of athree-phase power supply line, single-phase metal grounding, and phase losses, and has a great promotion and application value.

The invention relates to a moving contact device of a moulded case circuit breaker. The moving contact device is assembled by a moving contact, a support, a fixing pin, a disk spring, a compressing sleeve, a split washer, a hinge pin, a shaft sleeve, a tension spring and a rotation shaft, thus the simplest parts can be utilized to realize the dropproof device of the moving contact of the circuit breaker. When a line is broken, the electro-dynamic repulsion force generated by the short-circuit current is utilized to lift up the moving contact and keep a break distance, thus limiting the current and increasing the breaking capacity of the circuit breaker. In the moving contact device of the moulded case circuit breaker, the connection mode of the moving contact and the lead-out end is that the copper support is used to clamp the both sides of the moving contact, the flexible connection material is not required and the welding technology is not adopted; and the moving contact device has reliable structure and low cost and can achieve the aims of simple process, convenient installation, economy and practicability.

A mute electronic expansion valve comprises a valve shell, a valve rod, a valve rod supporting seat and a valve rod driving mechanism. The valve rod driving mechanism comprises a coil, a magnetic steel sleeve and a nut sleeve. A valve deck is sleeved with the coil which corresponds to the magnetic steel sleeve and can drive the magnetic steel sleeve to drive the nut sleeve to rotate. The valve rod supporting seat is sequentially divided into a nut sleeve motion supporting part and an installing supporting part in the axial direction. The valve rod is arranged in a central through hole of the valve rod supporting seat in a penetrating mode. The nut sleeve motion supporting part stretches into an inner cavity of the valve deck and is provided with a thread. Rotation and screw-thread fit of the nut sleeve drive the valve rod to move axially. An inner medium temporary storage cavity and an outer medium temporary storage cavity are formed between the installing supporting part and a valve seat, and at least one deflector hole penetrating through the inner medium temporary storage cavity and the outer medium temporary storage cavity is formed. After a medium is input through an input port, the medium is subjected to temporary storage and division of the outer medium temporary storage cavity, temporary storage of the inner medium temporary storage cavity and diameter change of the deflector holes, so that flow direction change, slowing and stabilizing of the medium are achieved, and the mute effect is achieved.

A level conversion circuit is provided, a first impedance and a second impedance with constant resistance are added to that exist level conversion circuit to act as current limiting. By setting the positions of the first impedance and the second impedance, new capacitance is avoided to be introduced into the first impedance and the second impedance, thereby affecting the high-speed transmission performance of the level shifting circuit. In addition, the level conversion circuit provided by the invention can also have good high-speed transmission performance when the VDD voltage changes, especially when the VDD is low. And the highest speed transmission capability of the level shifting circuit is improved compared with the prior art level shifting circuit.

The invention relates to a multi-breaker and thermotropic type resistor combined grading resistance rising fault current limiter which is low in cost, is suitable for 500KV-class and higher voltage classes, and improves operation safety of a power grid. According to the technical scheme, the multi-breaker and thermotropic type resistor combined grading resistance rising fault current limiter is connected from a bus, passes through a main breaker DL0 and a first group of grading resistance rising unit in sequence, and is connected to the direction of a power transmission line, from the second group of grading resistance rising unit to the (n-1)th group of grading resistance rising units are sequentially connected to the first group of grading resistance rising unit in parallel, the tail end of the first group of grading resistance rising unit is connected with a resistor Rn in parallel, the ith group of grading resistance rising unit is formed by connecting the ith breaker and a resistor Ri in series, the first group of grading resistance rising unit is connected with the second group of grading resistance rising unit through a high voltage isolating switch G1 and a high voltage isolating switch G2, the two ends of the resistor Rn are connected with an overvoltage protection lightning arrester FZ1 and an overvoltage protection lightning arrester FZ2 respectively and are grounded, the n is any natural number from three to nine, and the i is not smaller than 1 and not more than (n-1).

The invention relates to the technical field of natural gas pipeline detection, in particular to a device for inner leakage detection of a two-channel natural gas pipeline ball valve. The device comprises a power source, a first acoustic emission sensor, a second acoustic emission sensor, a signal amplifier, a boosting module, an analog-digital conversion module and a data acquisition module. The first and second acoustic emission sensors are connected with the signal amplifier, the signal amplifier is connected with the data acquisition module through a resistance regulation module; the data acquisition module is connected with an analytical equipment; the power source is connected with the signal source through the boosting module. The invention further provides a method for inner leakage detection of the two-channel natural gas pipeline ball valve. By the method, noise signals generated by the ball valve can be detected in the up stream and down stream of the natural gas pipeline ball valve at the same time, and whether or not inner leakage happens to the natural gas pipeline ball valve can be detected efficiently.

The invention relates to the technical field of circuit fault current limiting, and specifically relates to a short-circuit fault current-limiting transformer. The current-limiting transformer comprises a transformer and short-circuit protection circuits. The secondary coil of the transformer is composed of three identical secondary coils. A low-voltage tap is led out from each of the three secondary coils. One short-circuit protection circuit is connected between each low-voltage tap and the high-voltage end of the corresponding coil. Each short-circuit protection circuit is a current limiting loop in which one low-voltage tap is sequentially connected in series with an auxiliary reactor, a short-circuit protection switch and a capacitor and then connected with the high-voltage end of the corresponding secondary coil, wherein the capacitor is connected in parallel with a power supply switch, and the common joint of the power supply switch and the short-circuit protection switch is connected to a power supply circuit. At the moment when a line fails, a large impedance is added between the power supply and the fault point, and thus, the fault current is limited.

The invention discloses a low-voltage circuit breaker capable of improving breaking capacity. The low-voltage circuit breaker comprises a contact component comprising a moving contact and a fixed contact, wherein the moving contact and the fixed contact are respectively provided with contact parts; the contact parts of the moving contact and the fixed contact are respectively of double-layer structures of Ag-based alloy and Cu-based alloy, and the Ag-based alloy of the moving contact is in contact with the Ag-based alloy of the fixed contact when the moving contact and the fixed contact are adsorbed; metal oxide with a resistance value capable of positively changing along with the temperature is also arranged between the Ag-based alloy and the Cu-based alloy in the moving contact or the fixed contact; and the metal oxide is completely separated between the Ag-based alloy and the Cu-based alloy. By arranging a current limiting structure in the circuit breaker, the circuit breaker has a current limiting function, thereby being greatly convenient to use in different occasions.

The invention provides an electro-dynamic repulsion force short circuit current-limiting releasing technology of a liquid-magnet type miniature circuit breaker which is used for the over-current protection and the short-circuit protection in power transmission and distribution process, and particularly relates to the liquid-magnet type miniature circuit breaker which is used for the over-current protection and the short-circuit protection in the power transmission and distribution. The liquid-magnet type miniature circuit breaker thoroughly solves the problems that an existing liquid-magnet type miniature circuit breaker has no short-circuit current-limiting function and is not high in breaking capacity. The electro-dynamic repulsion force short circuit current-limiting releasing technology is that an electro-dynamic repulsion force short circuit current-limiting releasing mechanism is arranged between a movable contact and a fixed contact, when a short-circuit current appears, the movable contact and the fixed contact are rapidly separated under the action of electro-dynamic repulsion force, the current in a circuit is rapidly cut off, a voltaic arc is drawn long and thin in the process of cutting off the current, a large arc resistor is formed, an arc voltage is instantly improved, therefore, an expected short-circuit current can not be completely formed, and a role of limiting a current is played. Meanwhile, a movement pushing repulsion unlocking machine of the movable contact rapidly unlocks an unlocking control mechanism to enable the movable contact not to return and to turn on a return circuit.

The invention discloses an abnormality detection device and method for an electromagnetic brake, and relates to the technical field of electromechanical control. The abnormality detection device comprises a signal controller, an optical coupling input circuit, a switching control switch, a detection circuit, an optical coupling output circuit and a processor; the signal controller, the optical coupling input circuit, the switching control switch, an electromagnetic brake device, the detection circuit and the optical coupling output circuit are sequentially connected; the processor is connectedwith the signal controller and the optical coupling output circuit; the processor controls the signal controller to send a control signal; the optical coupling input circuit couples the control signal into the switching control circuit; the switching control circuit controls the electromagnetic brake device according to the control signal; the detection circuit detects the electromagnetic brake device and obtains a detection signal; the optical coupling output circuit couples the detection signal into the processor; and the processor judges whether the electromagnetic brake device is abnormalaccording to the control signal and the detection signal. According to the invention, whether a state of the electromagnetic brake is abnormal can be accurately judged according to the detection signal.

The invention provides an adjustable storage battery tester, comprising an instrument shell, a test circuit arranged in the interior of the instrument shell and a voltmeter arranged on the surface of the instrument shell, wherein the voltmeter circuit is connected with the test circuit; wherein the test circuit comprises a slide rheostat and an amperemeter which are sequentially connected between a first test terminal and a second test terminal in series and a voltmeter which is connected between the first test terminal and the second test terminal in parallel and also comprises a high power resistance R; the high power resistance R, the slide rheostat Rx and the amperemeter are connected in series; and discharge current can be changed by adjusting the resistance of the high power resistance R. The invention can meet the test discharge current requirement of storage batteries discharge current of which range from 5-50A and fills the gap of market; and the invention has the advantages that adjustment precise is high, volume is small, measuring ranges are multiple, and the instrument is convenient to carry. The invention has popularization advantage especially in automobile and help-move-vehicle fields.

The invention discloses a classroom blackboard LED lamp band driving circuit possessing a protection effect. The circuit comprises a bridge type rectification circuit, a voltage detection circuit, a power supply circuit, a microcontroller and a power conditioning circuit. A positive output terminal of the bridge type rectification circuit is connected to an input terminal of the voltage detectioncircuit, an input terminal of the power supply circuit and a positive input terminal of a blackboard LED lamp band. An output terminal of the voltage detection circuit and an output terminal of the power supply circuit are connected to the microcontroller. An output terminal of the microcontroller is connected to a signal control terminal of the power conditioning circuit. A negative output terminal of the bridge type rectification circuit is connected to an input terminal of the power conditioning circuit. An output terminal of the power conditioning circuit is connected to a negative input terminal of the blackboard LED lamp band. The voltage detection circuit comprises a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, a first diode, a first power supply and a first voltage output terminal. In the invention, the circuit structure is simple, cost is low, and safety and reliability of the circuit are high.

The invention is a starting resistance, including a resistance core, an insulating layer and electrodes connected with the resistance core and led out of the insulating layer, and its characteristic: the resistance core is mixed of a over 800-eye particulate material with the characteristic that the resistance reduces with the temperature increase at 0-300 deg.C, quartz powder and high aluminum powder, and binding by sodium silicate. As compared with existing technique, it is both small in bulk and able to solve the problems of long starting time of starter and high electric energy consumption of a three-phase cage asynchronous motor as well as high cost of manufacture and moisture proofing.

The invention discloses a direct-current distribution electronic soft start switch which comprises a main switch circuit, an auxiliary switch circuit, a first common end, a second common end, a thirdcommon end and a fourth common end. The main switch circuit comprises a power supply terminal, a signal terminal and a load terminal which are respectively connected with the first common end and thethird common end; the auxiliary switch circuit comprises a current limiting circuit composed of a semiconductor switch Qaux, a resistor Raux, a resistor R1 and a triode Q1, a buffer circuit composed of an inductor L1, a diode D1 and a capacitor C1, a timing turn-off circuit composed of a semiconductor switch Q3, a triode Q2, a resistor Rt and a capacitor Ct, a direct-current power supply module and a control circuit. The electronic soft start switch realizes soft start, safe turn-off and stable switching of fault current, is good in reliability, and is longer in service life and lower in costcompared with a mode of suppressing overvoltage by using a TVS device.