Abstract: The present invention provides a negative-pressure shield device with a simple device structure, which is relatively inexpensive to manufacture, and is extremely effective in preventing infection within an ambulance. The negative-pressure shield device comprises a shield main body that is installed in a patient compartment of an ambulance, includes a ceiling part and a peripheral wall part, and covers at least the head of a patient on a stretcher mounted in the patient compartment, and a connection part which communicates with the interior of the shield main body and connects to a ventilation opening provided in the patient compartment.

Abstract: A distance relay apparatus includes a directional relay element which performs computation to detect a fault, which occurs in the forward direction from an installing point of the relay apparatus, based on a voltage and a current which are received from an object to be protected, a zone-1 distance relay element which performs computation to detect a fault within a predetermined zone, a fault detecting relay element which performs computation to detect a fault within a zone that is narrower than that of the zone-1 distance relay element in terms of data time length which is shorter than that used for the computation of the zone-1 distance relay element, and a logic element which outputs a relay signal in accordance with a detecting operation of the zone-1 distance relay element, the fault detecting relay element, and the directional relay element.

Abstract: A distance relay apparatus includes a directional relay element which performs computation to detect a fault, which occurs in the forward direction from an installing point of the relay apparatus, based on a voltage and a current which are received from an object to be protected, a zone-1 distance relay element which performs computation to detect a fault within a predetermined zone, a fault detecting relay element which performs computation to detect a fault within a zone that is narrower than that of the zone-1 distance relay element in terms of data time length which is shorter than that used for the computation of the zone-1 distance relay element, and a logic element which outputs a relay signal in accordance with a detecting operation of the zone-1 distance relay element, the fault detecting relay element, and the directional relay element.

Abstract: A digital distance relay for deciding whether a fault point is within a stipulated operation region by obtaining an impedance to the fault point. The relay comprises: means for deciding whether the impedance is within a specified region by applying a value proportional to the relative phase; and means for deciding the fault point is within the stipulated operation region if: (a) when the load current indicates a sending direction, the positive-phase resistance and reactance are within a stipulated region based on stipulated positive-phase resistance and reactance, and the impedance is decided within the specified region; or (b) when the load current indicates a receiving direction, the positive-phase resistance and reactance are within a stipulated region based on stipulated positive-phase resistance and reactance, or the impedance is decided within the specified region.

Abstract: A digital distance relay for deciding whether a fault point is within a stipulated operation region by obtaining an impedance to the fault point. The relay comprises: means for deciding whether the impedance is within a specified region by applying a value proportional to the relative phase; and means for deciding the fault point is within the stipulated operation region if: (a) when the load current indicates a sending direction, the positive-phase resistance and reactance are within a stipulated region based on stipulated positive-phase resistance and reactance, and the impedance is decided within the specified region; or (b) when the load current indicates a receiving direction, the positive-phase resistance and reactance are within a stipulated region based on stipulated positive-phase resistance and reactance, or the impedance is decided within the specified region.

Abstract: A relay test apparatus for testing a protective relay operation of a protective relay system comprises GPS receivers, respectively connected to the protective relays, each GPS receiver analyzing time data included in a signal transmitted from a satellite and outputting a time signal, simulation signal generators, respectively connected to the protective relays, each simulation signal generator generating a simulation signal and inputting the simulation signal to a corresponding protective relay, and synchronous starting units, respectively provided in the protective relays, each synchronous starting unit starting a corresponding simulation signal generator to generate the simulation signal, when time signals output from the GPS receivers coincide with a preset time at a same time.

Abstract: A relay test apparatus for testing a protective relay operation of a protective relay system comprises GPS receivers, respectively connected to the protective relays, each GPS receiver analyzing time data included in a signal transmitted from a satellite and outputting a time signal, simulation signal generators, respectively connected to the protective relays, each simulation signal generator generating a simulation signal and inputting the simulation signal to a corresponding protective relay, and synchronous starting units, respectively provided in the protective relays, each synchronous starting unit starting a corresponding simulation signal generator to generate the simulation signal, when time signals output from the GPS receivers coincide with a preset time at a same time.

Abstract: A relay test apparatus for testing a protective relay operation of a protective relay system comprises GPS receivers, respectively connected to the protective relays, each GPS receiver analyzing time data included in a signal transmitted from a satellite and outputting a time signal, simulation signal generators, respectively connected to the protective relays, each simulation signal generator generating a simulation signal and inputting the simulation signal to a corresponding protective relay, and synchronous starting units, respectively provided in the protective relays, each synchronous starting unit starting a corresponding simulation signal generator to generate the simulation signal, when time signals output from the GPS receivers coincide with a preset time at a same time.

Abstract: A digital fault locator of this invention comprises a memory for storing input electric amount from a system and a plurality of digital filters having different filter functions to which electric amounts are supplied from the memory. A fault location is determined by selectively providing a specific one of outputs from the digital filters according to a fault time.

Abstract: In a digital distance relay including sample-hold circuits for sampling the voltage and current of an electric power line system, analog-digital converters for converting the outputs of the sample-hold circuits into digital values, memory devices for memorizing the digital values and a program, and a central processing unit for exercising a relaying operation, there is provided a central processing unit which includes means for determining whether at least one of the digital values is greater than a predetermined value. The relaying operation of the distance relay is initiated only when the one digital value is greater than the predetermined value. A method is disclosed which includes the above determining step.

Abstract: A digital type distance relay system comprises a sampling and hold circuit for sampling and holding the current in and voltage on a power transmission system, an A/D converter for receiving the outputs of the sampling and hold circuit through a multiplexer and converting the received analog quantities into corresponding digital quantities I and V, and a digital computer. The digital computer includes a data memory for memorizing the current I and voltage V and also a digital voltage V.sub.p having a predetermined relation to the voltage V, a setting memory for memorizing a setting value Z.sub.0 for setting a range of protection of the power transmission system, a ROM for memorizing a program for executing an arithmetic operation according to the formula .vertline.I.multidot.Z.sub.0 +K.sub.1 V.sub.p .vertline.-.vertline.I.multidot.Z.sub.0 -V-K.sub.2 V.sub.p .vertline..gtoreq.K.sub.0 as well as the constants K.sub.1 and K.sub.2 and minimum sensitivity value K.sub.0, and a CPU.

Abstract: In a method and a system for protecting an electric power system, a signal useful for the protection is produced through operation on a digital data q.sub.m indicative of an instantaneous value at a first time point of an AC electrical quantity and another digital data given by 1/2{axq.sub.m-n -(2-a)xq.sub.m-n+l } where q.sub.m-n and q.sub.m-n+l represent data indicative of instantaneous values of an AC electrical quantity, at a time point in advance of the first time point by an angle of .alpha..degree. (0.ltoreq..alpha..ltoreq.180), and at a time point lagging behind the first time point by an angle of (180-.alpha.).degree., respectively, and a equals to .alpha./90.

Abstract: In a digital distance relaying system the principle of comparing the amplitude values of alternating current quantities is used. In one example, amplitude values of V and V-IZ are compared and in the other example the amplitude values of V-IZ and IZ are compared for determining the operating point of the relay system.

Abstract: The amplitude value of a sinusoidal wave is calculated by operating means which processes absolute values of two data samples which are sampled from the sinusoidal wave at two points spaced 90.degree. electrical degrees apart thereby producing an electrical signal proportional to the amplitude value. The operation means comprises a comparator, a combination of an adder and a subtractor, or a combination of a comparator and an adder. The output of the comparator or the combination is multiplied with a predetermined coefficient and then added together to produce said signal.

Abstract: The apparatus comprises a sampling hold circuit for sampling the amplitude of a sinusoidal wave at a predetermined frequency, a data sample extracting circuit for extracting two data samples at two points immediately before and after the peak value of the sinusoidal wave, and an operation circuit responsive to the absolute values of the two data samples for calculating the amplitude value of the sinusoidal wave.