34results about How to "Small residual current" patented technology

The invention discloses an arc-suppression method of a ground fault in a neutral non-grounding system and an apparatus thereof. A power supply apparatus is connected to a neutral line in the neutral non-grounding system. Through the power supply apparatus, a compensation voltage is output so as to compensate a fault current of the system so that an arc-suppression purpose is reached. An output voltage of the power supply apparatus is defined in the description, wherein omega is a fundamental wave angular frequency; ic, iR and ih are capacitive, resistive and harmonic wave currents respectively; n is a harmonic order; a zero sequence voltage on a neutral point is defined in the description and L is an equivalent inductance of a power supply system. The arc-suppression method of the ground fault in the neutral non-grounding system and the apparatus are easy to carry out and arc suppression can be effectively enforced aiming at a single-phase ground fault.

The invention discloses a PTC thermosensitive resistor based on a conducting polymer and application of the PTC thermosensitive resistor. The PTC thermosensitive resistor based on the conducting polymer is prepared from polyimide, polyacetylene, phenolic epoxy resin, conductive filler, thermal conducting filler, silicon dioxide, calcium oxide and talcum powder. The PTC thermosensitive resistor based on the conducting polymer has the advantages of being high in temperature sensibility, short in response time, low in residual current and high in stability, has the excellent winding property and fracture resistance, can be widely applied to automatic temperature-control heaters such as a plate-type automatic temperature-control heater, an automatic temperature-control heating band, a tubular automatic temperature-control heater and an automatic temperature-control heating cable which have various shapes and is long in service life.

The invention discloses a preparation method of a hyaluronidase modified vanadium nitride paste electrode sensor. The preparation method is characterized by comprising the following steps: preparing anano VN/graphene composite paste electrode from nano VN, graphene oxide, N-ethyl-3-methylpyridine hexafluorophosphate; then, modifying the nano VN/graphene composite paste electrode with gamma-glycidyl ether oxopropyl trimethoxy silane to obtain a gamma-glycidyl ether oxopropyl trimethoxy silane modified nano VN/graphene composite paste electrode; preparing hyaluronidase stationary liquid from deionized water, bovine serum albumin, hyaluronidase and polyvinyl alcohol; finally, dropwise applying the hyaluronidase stationary liquid to the gamma-glycidyl ether oxopropyl trimethoxy silane modified nano VN/graphene composite paste electrode, and drying to obtain the hyaluronidase modified vanadium nitride paste electrode sensor. With higher electrical conductivity than a common carbon paste electrode, the electrode sensor is specific to hyaluronic acid and has high sensitivity.

The invention discloses a preparation method of a quantum dot/enzyme compounded carbon paste electrode for detecting SAM (S-Adenosylmethionine). The preparation method is characterized by comprising the following steps of doping water-soluble CdZnTe quantum dots and transmethylase in a carbon paste electrode; by taking 1-ethyl-3--methylimidazolium hexafluorophosphate as an adhesive, mixing a carbon nano-tube with graphite powder to prepare the carbon electrode, so as to obtain the quantum dot/enzyme compounded carbon paste electrode; compared with an ordinary carbon paste electrode, the quantum dot/enzyme compounded carbon paste electrode has the advantages of conducting property improved by 1 to 2 times, wide electrochemical window, simple preparation method, low cost, easy update for surface, low residual current and the like; the eelctrode can be used for quickly detecting the SAM in a sample; the method has the characteristics of high sensitivity, good selectivity, short response time and low interference, is superior to other detection methods, and is a determination method with simpleness, quickness, convenience and feasibility for the SAM. A fixed methyltransferase electrode sensor prepared by the preparation method disclosed by the invention is low in cost, simple in preparation process and good in specificity, and has the possibility of realizing automated field determination.

The invention discloses a preparation method of a nano-TiC/graphene composite paste electrode sensor. The preparation method of the nano-TiC/graphene composite paste electrode sensor is characterizedby comprising the following steps: treating graphene by using concentrated sulfuric acid and ammonium persulfate to obtain pretreated graphene; then adding 42 to 46% of nano-TiC, 21 to 25% of pretreated graphene, 20 to 25% of N-ethyl-3-methylpyridine tetrafluoroborate and 8 to 12% of silicone oil respectively in an agate mortar, and uniformly grinding to obtain a mixture of carbon paste; placing the carbon paste of the mixture in a glass tube connected with a wire and of which the inner diameter is Phi 5mm, performing compaction, drying, sanding with metallographic sandpaper, polishing, and washing with deionized water, thereby obtaining the nano-TiC/graphene composite paste electrode sensor. The carbon paste electrode prepared by the application has the advantages of having 4 to 5 times higher conductivity than that of the ordinary carbon paste electrode, wide electrochemical window, simple preparation method, low cost, easy surface renewal, small residual current and the like, and isfurther high in detection sensitivity of cefoxitin and good in selectivity.

The invention discloses a coaxial compound oxygen microelectrode and a preparation method thereof. The oxygen microelectrode includes an external casing, a working cathode column located at the central part, and a reference electrode located between the external casing and the working cathode column, the central part of the working cathode column is provided with a platinum wire, an electrolyte solution is filled between the external casing and the working cathode column, the outer wall of the working cathode column or the inner wall of the external casing is plated with a layer of silver layer, and the upper end surface of the silver layer is welded with a conductive metal wire to form a protection cathode. The electrode making process is simple, and high in control success rate, the results show that the protection cathode switches on to reduce residual current of the coaxial compound oxygen microelectrode by about 80%, dissolved oxygen response linear dependence R2 is more than 0.99, and the dissolved oxygen resolution is about 0.03 mg O2/L.

The embodiment of the application discloses a neutral point grounding mode switching device and method. When a distribution network is in normal operation, a controller turns off a control switch of a grounding resistor, simultaneously monitors the grid capacitance current, and determines the combination state of an adjustable capacitor bank of an arc suppression coil. When a single-phase ground fault occurs in the distribution network, the controller adjusts the arc suppression coil to an over-compensation state according to the combination state of the adjustable capacitor bank, and gives full scope to the effect that the low residual current of a fault point slows down the recovery voltage rise speed of the fault phase under an arc suppression coil grounding mode so that the transient fault automatically disappears. When the duration of the single-phase ground fault occurring in the distribution network is greater than a preset duration, the control switch is turned on in order that the neutral point is grounded through the arc suppression coil and is grounded through the grounding resistor.

The invention discloses a fabrication method of a bismuth-doped nanometer SiC/carbon nanotube paste electrode sensor. The fabrication method is characterized by comprising the steps of dissolving bismuth citrate and cellulose by employing 1-butyl-3-methylimidazole chlorine salt to prepare faint yellow viscous liquid being a bismuth-doped carbon quantum dot-containing adhesive; uniformly grinding 45-48wt% of nanometer SiC, 25-28wt% of carbon oxide nanotube, 10-14wt% of bismuth-doped carbon quantum dot-containing adhesive, 4-6wt% of polyethylene glycol and 8-12wt% of ethyl alcohol in an agate mortar, thereby obtaining nanometer SiC/carbon nanotube/bismuth-doped carbon quantum dot mixture carbon paste; and loading the mixture carbon paste in a glass tube connected with a wire having inner radius being 5 millimeters, thereby obtaining the bismuth-doped nanometer SiC/carbon nanotube paste electrode sensor. Conductivity of the electrode fabricated by the method is improved by 4-6 times compared with a conventional carbon paste electrode, the electrode has the advantages of wide electrochemical window, simple fabrication method, small residual current, high detection sensitivity and goodselectivity and the like, and a surface is easy to update.

The invention discloses a method for preparing a nano TiB2/carbon nano tube composite paste electrode sensor. The method is characterized by comprising the following steps: pre-treating carbon nano tubes with concentrated sulfuric acid and ammonium persulfate to obtain pretreated carbon nano tubes; respectively 38-42% of nano TiB2, 23-26% of pretreated carbon nano tubes, 25-30% of 1-allyl-3-methylimidazolium tetrafluoroborate and 6-10% of glycerin into an agate mortar, and uniformly grinding to obtain the mixture carbon paste; and filling the carbon paste into a glass tube which is connected with a wire and has an inner diameter of Phi 5 mm, compacting, drying, polishing by abrasive paper for metallograph, polishing, and washing with deionized water, thereby obtaining the nano TiB2/carbonnano tube composite paste electrode. Compared with that of an ordinary carbon paste electrode, the conductivity of the carbon paste electrode prepared in the invention is improved by 4-5 times, and the carbon paste electrode has the advantages of being wide in electrochemical window, simple in preparation method, low in cost, easy for surface renewal, low in residual current and the like. The cefixime detection sensitivity is high, and the selectivity is excellent.

The invention discloses a preparation method of a sulfoaminobiotin modified indium nitride paste electrode sensor, and the method is characterized in that the method comprises the steps: preparing a indium nitride paste electrode sensor from nano indium nitride, graphene oxide, 1-aminopropyl-3-methylimidazolium bromide, mineral oil and pentanol; modifying the indium nitride paste electrode by adopting triethylenetetramine and carbon quantum dots to prepare a triethylenetetramine/quantum dot modified indium nitride paste electrode; adding 92-96% of phosphate buffer solution and 4-8% of sulfoaminobiotin into a reactor, performing dissolving, putting the triethylenetetramine/quantum dot modified indium nitride paste electrode into the solution, performing stirring and soaking for 2 hours at room temperature, taking out the electrode, and performing washing and drying to obtain the sulfoaminobiotin modified indium nitride paste electrode sensor. Compared with a common carbon paste electrode, the electrode sensor is higher in conductivity, has specific recognition performance on protein and is high in sensitivity.