Abstract: A synchronous switching apparatus for detecting a source voltage of each phase to close each phase at an electrical phase angle predetermined for each phase, including switching devices 1a-1c provided one for each phase for opening and closing an impedance load, switching devices 2a-2c for closing and opening the switching devices 1a-1c for each phase, measuring transformers 5a-5c for measuring source voltages of the respective phases and phase-to-phase voltages, and phase control devices 42 each for issuing a command for energizing the impedance load at an electrical phase angle in a range predetermined for each phase, when detecting a zero point of a source voltage of each phase or a zero point of each phase-to-phase voltage.

Abstract: A phase control switching system for controlling opening and closing timings of a power switching device to suppress the occurrence of an exciting rush current or a make-and-break surge voltage which is severe to system equipment such as a transformer, a reactor and a capacitor bank, or for controlling an arcing time of a circuit breaker to put the circuit breaker into operation for the arcing time leading to no-re-ignition or for the optimal breaking time. In the phase control switching system, a current measuring section or a current gradient measuring section is provided to measure a current value or a current gradient value of a current to be broken or introduced, and a reference phase detecting section estimates a current zero point of a current waveform on the basis of the measurements. Subsequently, a control section, upon receipt of an opening/closing command, an opening phase control operation using an arbitrary time point after the current waveform estimation as a reference.

Abstract: A porous lithium aluminate carrier for catalyst has a spinel structure which has a mean pore diameter in the range of 40 to 1,000 angstroms and a total pore volume in the range of 0.2 to 1.5 mL/g. The porous lithium aluminate carrier can be used for supporting a catalyst compound containing a platinum group metal. The catalyst on the carrier can be favorably employed for promoting catalytic reaction of a nitrite ester and carbon monoxide to prepare a carbonate diester such as dimethyl carbonate.

Abstract: A porous lithium aluminate carrier for catalyst has a spinel structure which has a mean pore diameter in the range of 40 to 1,000 angstroms and a total pore volume in the range of 0.2 to 1.5 mL/g. The porous lithium aluminate carrier can be used for supporting a catalyst compound containing a platinum group metal. The catalyst on the carrier can be favorably employed for promoting catalytic reaction of a nitrite ester and carbon monoxide to prepare a carbonate diester such as dimethyl carbonate.

Abstract: A switch for use in electric power includes a fixed contact, a moving contact performing a switching operation with respect to the fixed contact, a cylinder working with the moving contact, a piston slidably provided in the cylinder, a buffer chamber which is surrounded by the cylinder and the piston, and is filled with an arc-extinguishing gas, and a second insulating nozzle mounted to an end of the cylinder on the side of the fixed contact, wherein the arc-extinguishing gas in the buffer chamber is sprayed through the nozzle on an arc generating between the fixed contact and the moving contact at an opening time of the moving contact.

Abstract: In a double-break type circuit breaker having resistor contacts which are to be connected in parallel with main contacts in not only closing operation but also breaking operation, the resistor contacts are opened by a force due to loading of elastic members in the breaking operation and the elastic members are loaded for storing the driving force In the closing operation.

Abstract: In a stationary contact unit of a gas circuit breaker, an arc-quenching cylinder for passing an arc-quenching insulation gas is formed in a substantially semicircular shape, and the stationary contact unit is supported by an insulation frame which is disposed beneath the dent part of the semicircular portion of the arc-quenching cylinder. The insulation frame is prevented from the degradation of dielectric strength between the stationary contact unit and a grounded tank, and the size of the gas circuit breaker is decreased.

Abstract: In a closing operation of a circuit breaker with resistor contact, a resister contact is closed prior to closing of a main contact by the same first hydraulic operation system. In opening operation, the resistor contact is driven by a second hydraulic operation system used to close the main contact after operating the main contact by the first hydraulic operation system. Opening timing of the resistor contact is controlled by a mechanical interlock mechanism or hydraulic control circuit.

Abstract: A double-break type circuit breaker includes two resistor contacts which are to be connected in parallel with respectively two main contacts when the main contacts are closed. An engagement mechanism is provided for linking the main contacts operated by a first hydraulic operation apparatus and the resistor contacts operated by a second hydraulic operation apparatus.

Abstract: A catalyst for the ammoxidation of propylene to prepare acrylonitrile with a high yield thereof comprising an oxide composition of the empirical formula (I)Mo.sub.a Co.sub.b Ni.sub.c Fe.sub.d Bi.sub.e V.sub.f Ca.sub.g K.sub.h X.sub.i Si.sub.j O.sub.k (I)wherein X is zirconium and/or chromium, the subscripts a, b, c, d, e, f, g, h, i and j respectively denote the number of the respective atoms of the elements, when a=10, b=0 to 8, c=0 to 8, (b+c)=2 to 10, d=0.3 to 7, e=0.01 to 3, f=0.01 to 2, g=0.01 to 5, h=0.05 to 0.5, i=0 to 2, j=10 to 50, and the subscript k denotes the number of oxygen atoms which satisfies the average valency of the elements other than oxygen and the ratio a:k being in a range of 10:30 to 80, which catalyst is prepared by preparing an aqueous slurry containing respective element-containing compounds, by spray drying the aqueous slurry to prepare a dried solid precursory catalyst and, finally, by calcining the precursory catalyst as a temperature of from 500.degree. to 750.degree. C.

Abstract: An improved catalyst suitable for use in the production of acrylonitrile by the catalytic ammoxidation of propylene in a fluidized bed reactor is provided. This catalyst contains 40 to 60% by weight of silica, in terms of SiO.sub.2 , and 60 to 40% by weight of a composition having the formula:Mo.sub.10 Co.sub.2-8 Ni.sub.0-8 Fe.sub.0.1-7 Bi.sub.0.1-3 Zr.sub.0.1-4 A.sub.0.01-1 X.sub.0-5 O.sub.32.5-78.5wherein A is the alkali metals, X is Ti, Te, V, Mn, Cr, W and/or Sn, provided that the total number of Co and Ni atoms is 2 to 10, and has 150 to 500 A of the average pore radius, 0.2 to 0.5 cm.sup.3 /g of the total pore volume and 30 to 60 m.sup.2 /g of the specific surface area. This catalyst has an improved attrition resistance and acrylonitrile can be produced, in the presence of this catalyst, at a high yield by the ammoxidation reaction of propylene in a fluidized bed reactor.

Abstract: Acrylonitrile can be catalytically produced with a high yield by bringing, at an elevated temperature, preferably of 300.degree. to 470.degree. C., a reaction feed containing propylene, ammonia and molecular oxygen into contact with a catalyst consisting of an oxide composition of the empirical formula: Mo.sub.a Co.sub.b Fe.sub.c X.sub.d O.sub.e wherein X denotes at least one atom of an element selected from phosphorus, arsenic, antimony and bismuth and wherein the ratio a:b:c:d:e is in a range of 12:4 to 9:1 to 5:0.01 to 0.07:39.5 to 52.7, said catalyst being prepared by providing an aqueous mixture containing molybdenum-, cobalt- and iron-containing compounds and a phosphorus-, arsenic-, antimony- or bismuth-containing compound, converting the aqueous mixture into a dried solid mixture and calcining the solid mixture at a temperature of at least 550.degree. C.

Abstract: High-yield catalytic production of acrylonitrile at an elevated temperature, from a reaction mixture containing propylene, ammonia and molecular oxygen, utilizing a catalyst comprising an oxide composition having the empirical formula Mo.sub.a Co.sub.b Fe.sub.c X.sub.d O.sub.e wherein X denotes at least one atom of an element selected from among calcium, tungsten, chromium, zirconium, titanium, zinc, manganese, and tin and the atomic ratio a:b:c:d:e is in the range of 12:4 to 10:1 to 6:0 to 1.0:40 to 70, said catalyst being prepared by providing an aqueous mixture containing compounds of the elements, drying the aqueous mixture, and calcining the dried solid product at a temperature of at least 500.degree. C.

Abstract: Acrylonitrile can be produced in a high yield by the catalytical ammoxidation of propylene at an elevated temperature, preferably of 330.degree. to 470.degree. C, in the presence of a new type of catalyst consisting of an oxide composition of the empirical formula: Mo.sub.a Co.sub.b Fe.sub.c Bi.sub.d X.sub.e O.sub.f wherein X denotes at least one atom of an element selected from vanadium and tellurium and wherein the ratio a:b:c:d:e:f is in a range of 10:3 to 10:1 to 7:0.1 to 0.7:0.01 to 1:34.6 to 54.1, said catalyst being prepared by providing an aqueous mixture containing molybdenum-, cobalt- and iron-containing compounds, bismuth-containing compound, and vanadium-or tellurium-containing compound, converting the aqueous mixture into a dried solid mixture and calcining the solid mixture at a temperature of at least 500.degree. C.