Controlled switching device

Abstract: A close control signal or an open control signal is outputted after a wait time of a half cycle or less upon a close command or an open command to a breaker in order to make a breaker at a predetermined interpole voltage phase or to open a main circuit current at a predetermined phase. When the close command or the open command is detected, a delay time is determined based on latest zero point time and a predicted close time or a predicted open time, and the close control signal or the open control signal is outputted after a lapse of the delay time so as to make or to open a pole at the predetermined phase of the interpole voltage or the main circuit current.

Description: BACK_GROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a controlled switching device for controlling open and close timing of a breaker and for preventing a harmful phenomenon for a system and an apparatus from occurring, in particular, to a structure of a control device for the controlled switching device. DISCUSSION OF BACKGROUND Japanese Unexamined Patent Publication JP-A-3-156820 discloses a controlled switching device, which does not generate a transitional phenomenon influencing systems and apparatuses regardless of a make break condition. In such a controlled switching device, a device for controlling timing of opening a pole is provided in a breaker so that contacts are sufficiently spaced at time of cutting off a current. Further, the device for controlling the timing of opening the pole controls timing of closing the pole in the breaker in response to a type of a load. Japanese Unexamined Patent Publication JP-A-6-20564 discloses an open control device for a breaker used as a shunt reactor, in which a pole is opened without reigniting. In the open control device for the breaker, because a high frequency reignition surge generated at time of opening the pole of shunt reactor does not exist when a final breaking point of the breaker is a current phase zero point, a single-phase voltage is inputted into the control device from an instrument transformer. In the control device, each current phase is calculated based on a phase of the single-phase voltage and outputs a command of opening the pole to the breaker so that a current, which flows through the shunt reactor, is cut off at a current zero point of each phase. In the above-mentioned control devices, a control signal is outputted to control close timing or open timing by detecting a zero point of a current or a voltage of a main circuit after a close command or an open command is inputted and by changing a time for urging a releasing device or the device for controlling to close the pole based on the detected zero point. Therefore, it is necessary to wait for a time from inputting the close command or the opening command until detecting a next voltage zero point or a next current zero point. Resultantly, there is a problem that a dead time of a maximum one cycle occurs between the input of the closing command or the opening command and urge of the releasing device or the device for controlling to close the pole. Further, an operating time of the breaker is corrected by a correction curve of a control voltage expressed by a primary expression or a secondly expression, and the breaker does not have a function of dealing with a displacement of the acting time by an environmental temperature change, that between devices, that between phases, that caused by aged deterioration, and so on. Therefore, there is a problem that a function of constantly closing or opening the pole at predetermined timing is hardly realized. Further, there is a problem that the zero point is not accurately detected when a sudden noise of an impulse type or a higher harmonic is superposed on a detection signal when the zero point of the current or the voltage is detected. Also there is a problem that the pole is not closed or opened at predetermined timing when a frequency is varied because the control device do not have a function of dealing with a frequency variation of the voltage or the current. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems inherent in the conventional technique and to provide a controlled switching device, which outputs a close control signal or an open control signal after latency of a half cycle or less with respect to a close command or an open command when a pole is closed or opened at predetermined timing with respect to the close command or the open command and can make a breaker at a predetermined interpole voltage phase or can open the pole at a predetermined phase of a main open current. According to a first aspect of the current invention, there is given a method of closing a breaker at a target make phase of an AC interpole voltage applied across poles of the breaker. The target make phase is a target zero point of both a voltage and a current, measured from a position after a half cycle from a starting point in which a current starts to flow through a main circuit after a close operation. The device comprises an interpole voltage measuring means used for detecting an interpole voltage zero time point, which is when the interpole voltage is instantaneously zero. This is based on the measured interpole voltage. Further, there are control means to output a close control signal. The method includes the interpole voltage measuring means storing in a memory, over time, a plurality of detected interpole voltage zero time points. Then, the control means predicts a predicted close time of the poles, measured from the output of the close control signal to the actual closing of the poles at a target close point. The control means then determines: a close command detection time, which is the time measured from the interpole voltage zero time point preceding and closest in time to a close command to the receipt of the close command. The control means further obtains a pre-arc time, which is measured from a target make phase to the actual closing at the target close point. The control means then determines a close control delay time, from receipt of the close command until issue of the close command signal within one-half period of the interpole voltage, and finally outputs the close control signal after lapse of the close control delay time so that the making is completed at the target make phase. According to a second aspect of the present invention, there is provided the method of closing the breaker according to the first aspect of the invention, wherein the control means continuously evaluates the zero time points a number of times preceding and closest in time to receipt of the close command. It then minimizes deviations with respect to each of the zero time points evaluated, from a product of one-half period of the interpole voltage and an integer, and selects the zero time point from times with the minimum sum of absolute values of the deviations, just before the receipt of the close command and closet in time to the receipt of the close command. According to a third aspect of the present invention, there is provided the method of closing the breaker according to the first aspect of the invention, wherein the control means predicts the predicted close time. This predicted close time is determined by correcting a reference close time, based on a reference environmental condition and a measured environmental condition, by consulting a close time correction table for the measured environmental condition. According to a fourth aspect of the present invention, there is provided the method of closing the breaker according to the first aspect of the invention, wherein the control means comprises close time detection means for detecting time of closing of the switch poles. Further, operating time measuring means are provided for acquiring an observed close time, measured from the close control signal until closing of the switch poles. The control means then corrects its reference close time based on a measured environmental condition, by consulting a close time correction table based on the environmental condition. According to a fifth aspect of the present invention, there is provided the method of closing the breaker according to the first aspect of the invention. Here, the control means detects the rise time of the main circuit current flowing at the closing of the poles, based on the operating time measuring means acquiring an observed close time, by adding the pre-arc time to the delay from the output of the close control signal, until the rise time of the main circuit current. The control means then corrects a reference close time, based on a measured environmental condition, by consulting a close time correction table based on the measured environmental condition. According to a sixth aspect of the present invention, there is provided the method of closing the breaker according to the first aspect of the invention. Here, the control means measures a fixed number of continuous zero time points preceding and closest in time to receipt of the close command. It then acquires local frequencies of the interpole voltage from delays between adjacent zero time points, and determines a frequency of the interpole voltage as an average of these local frequencies. According to a seventh aspect of the present invention, there is given a method of breaking a breaker at a target make phase of an AC interpole voltage applied across poles of the breaker. The target open phase is a target zero point of a voltage and a current, measured from a position after a half cycle from a starting point in which a current stops flowing through a main circuit after an open operation. The device comprises: a main circuit current measuring means, for measuring an AC main circuit current flowing through the poles of the breaker when closed. Zero point time detecting means, for detecting an interpole current zero time point which is when the current flowing through the breaker is instantaneously zero, which is based on a measured main circuit current. Further there are control means for outputting a close control signal. The method includes the steps of: using the zero time point detection means to store in a memory, over time, a plurality of detected interpole current zero time points. Using the control means to predict a predicted open time of the poles, measured from the output of the open control signal to the moment of actual opening of the poles at the target phase. The control means then determines an open command detection time, which is measured from the main circuit current zero time point preceding and closest in time to an open command, to receipt of the open command. Then these control means determine an open control delay time within one-half period of the main circuit current, and finally output the open control signal after lapse of the open command detection time and the open control delay time, so that circuit breaking is completed at the target open phase. According to a eighth aspect of the present invention, there is provided the method of closing the breaker according to the seventh aspect of the invention. Here, the control means continuously evaluate the zero time points a number of times preceding and closest in time to receipt of the open command. Then, they minimize the deviations with respect to each of the zero time points, which are evaluated from a product of one-half period of the main circuit current and an integer. Finally, the control means selects the main circuit current zero time point, from times within the minimum sum of absolute values of the deviations, just before receipt of the open command and closest in time to receipt of the open command. According to a ninth aspect of the present invention, there is provided the method of closing the breaker according to the seventh aspect of the invention. Here, the control means predicts the predicted open time by correcting a reference open time, which is based on a reference environmental condition, by a measured environmental condition after consulting an open time correction table for the measured environmental condition. According to a tenth aspect of the present invention, there is provided the method of closing the breaker according to the seventh aspect of the invention. Wherein, the control means comprises open time detection means for detecting the time of opening of the switch poles, and operating time measuring means, for acquiring an observed open time from the open time of the open control signal. The control means further corrects a reference open time for a measured environmental condition, by consulting an open time correction table based on the environmental condition. According to a eleventh aspect of the present invention, there is provided the method of closing the breaker according to the seventh aspect of the invention. Here, the control means uses a fixed number of continuous main circuit current zero time points, preceding and closest in time to receipt of the open command. Further, they acquire local frequencies of the main circuit current from delays between adjacent main circuit current zero time points. Finally, the means determine a frequency of the main circuit current of the breaker as an average of the local frequencies. BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and main of the attendant advantage thereof will be readily obtained as the same becomes better understood by reference to the following detail description when considered in connection with the accompanying drawings, wherein: Figure 1 is a block chart of a controlled switching device according to Embodiment 1 of the present invention; Figure 2 is a flow chart explaining an entire operation of the controlled switching device according to Embodiment 1 of the present invention; Figure 3 is a time chart explaining a zero point evaluation process; Figure 4(a) illustrates a concept of a correction table concerning an operating time; Figure 4(b) illustrates a concept of a correction table concerning an operating time; Figure 5 is a time chart explaining a pre-arc time at time of closing a pole; Figure 6 is a block chart of a controlled switching device according to Embodiment 2 of the present invention; Figure 7 is a time chart explaining a method for detecting a make time by a current signal; and Figure 8 is a block chart of a controlled switching device according to Embodiment 3 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed explanation will be given of preferred embodiments of the present invention in reference to figures 1 through 8 as follows, wherein the same references are used for the same or similar portions and description of these portions is omitted. Embodiment 1 Hereinbelow, a controlled switching device, to which the present invention is applied, will be described in reference of figures. Terminology is based on JISC4603 concerning high voltage a.c. current breaker unless otherwise described. However, a scope of the invention is not limited to a content of JISC4603. Figure 1 is a block chart of a controlled switching device according to Embodiment 1 of the present invention. In figure 1, numerical reference 100 designates a main circuit, numerical reference 200 designates a breaker connected to the main circuit 100, numerical reference 300 designates an operation device, and numerical reference 400 designates a control device. Numerical reference 1 designate an interpole voltage measuring means for detecting an interpole voltage of the breaker 200, numerical reference 2 designate a main circuit current measuring means for detecting a current of the main circuit 100. Numerical reference 3 designate a zero point detection means, which acquires zero point times of the interpole voltage and a main circuit current from a voltage signal and a current signal, which are detected by the interpole voltage measuring means 1 and the main circuit current measuring means 2, and constantly memorizes latest zero point times of the interpole voltage and the main circuit current. Numerical reference 4 designate an operating time predicting means for predicting a close time or an open time of the breaker 200. Numerical reference 5 designate a control signal output means, which acquires latency based on the latest zero point time memorized in the zero point detection means 3 and a predicted close time or a predicted open time, both are obtained by the acting time prediction means 4, and outputs a close control signal or an opening control signal, by which a close control device or a tripping device is urged, after a lapse of the latency. A terminology "make" means that a current starts to flow through the main circuit by a close operation. Further, discharge generated between contacts of the breaker depends on an absolute value of a voltage applied between the contacts, whereby a terminology "phase" is measured from a position after a half cycle from a starting point, being a zero point of a voltage and a current. Numerical reference 41 designates an operating time measuring means, which acquired an observation close time from an output of the close control signal under operation and a time when the contact is in contact or an observation open time between an output of the open control signal and a time when the pole is opened, based on an operating time of an auxiliary switch 201 acting simultaneously with a contacted state of the contact when the pole is closed and an open of the pole under an opening operation, wherein the acting time measuring means is interlocked with a movable contact which is movable. Further, although an auxiliary switch is used as the acting time measuring means 41, it is also possible to provide a rotation angle measuring means such as a rotary encorder provided in a rotation shaft for driving the movable contact of the breaker 200 and to acquire the observation close time and the observation open time depending on a positional signal of the movable contact, which signal is obtained by the rotation angle measuring means. Further, it is possible to obtain an effect that an operation of a working part of the breaker is easily monitored by providing the rotation angle measuring means. Numerical reference 42 designates an environmental temperature measuring means, which measures an environmental temperature around the breaker 200. Numerical reference 43 designates a control voltage measuring means which measures a control voltage, wherein a terminology "control voltage" contains a meaning of an operation voltage. An acting time predicting means 4 corrects a reference close time and a reference open time, both of which are acting times under a reference environmental condition of the breaker 200 and acquires a predicted close time or a predicted open time based on an environmental condition, the reference close time and the reference open time. Figure 2 is a flow chart explaining an entire operation of the controlled switching device. Significance of parts of the flow chart will be described. The interpole voltage measuring means 1 and the main circuit current measuring means 2 sequentially digitize an analog signal from a power transformer (PT) and a current transformer (CT), both are located in the main circuit 100, by an a.d. converter at predetermined sampling intervals, whereby a voltage signal and a current signal both as digital data are acquired. Hereinbelow, the voltage signal and the current signal are digital signals unless otherwise described. When a harmonic noise and so on are superposed on an analog signal, a detection accuracy of the zero point detection means 3 is deteriorated. Therefore, it is possible to adapt a structure that a low-pass filter may be inserted ahead the a.d. converter for removing the harmonic noise and so on. Further, the voltage signal or the current signal may be smoothed. For example, by providing a central value filter for filtering representative values several points ahead and behind a central value of data subjected to treatment, it is possible to remove a noise shaped like a needle in the data. Further, by constructing a low pass filter in use of a digital filter, it is possible to remove a harmonic noise and so on, which exceeds a frequency of the main circuit, out of the voltage signal or the current signal. In the zero point detection means 3, the zero point time of the voltage or the current is acquired from the voltage signal, the current signal and measured times of these periods when a sign of the voltage signal or the current signal is changed from a negative to a positive or from a positive to a negative, the zero point time is determined by: t 0 =t 1 +|S·A 1 /(A 1 +A 2 )| where symbol t 1 represents a final sampling time before the change; symbol A 1 represents a value at the final sampling time before the change; symbol A 2 represents an initial sampling value after the change; and symbol S represents a sampling interval. Thus acquired zero point times to respectively for the voltage signal and the current signal are memorized in predetermined memories. Needless to say that the zero point times may be detected by a zero-crossing detector. It is desirable that one with a highest reliability out of thus acquired plurality of zero point times, which are preceeding and closest, in order to acquire a zero point time, which is a standard of an accurate operation of the breaker and by which an influence of a high harmonic noise and so on is removed from the voltage signal or the current signal. Hereinbelow, such usage is named a zero point evaluation process. An operation of the zero point evaluation process will be described. Figure 3 explains a method of the zero point evaluation process. A time when the zero point time is evaluated is referred to as a present time. Points as much as n preceeding and closest to the zero point, for example 5 points, are stored in a memory. A difference between a pair of arbitrary two points is calculated each for the n zero point times. Although when differences of d 1 through d n-1 between one of the zero point time and the other zero point times as much as n-1 are obtained, every difference should be a power of a cycle of the interpole voltage or a half of a period of the main circuit current and integers, wherein the half of the period is simply referred to as half period, and a half cycle after a starting point of the zero point of the voltage and the current is referred to as half period. However, a deviation of latency between the zero point times from a power of a half period and integers occurs by a variation of a system frequency, a variation of a phase accompanied by a load variation, and an existence of a high harmonic. In the zero point evaluation in the controlled switching device, a zero point time preceeding the present time when a power of a half cycle and integers passes after a zero point time closest to the present time is acquired among the zero point times, in which a sum of absolute values of the deviations is minimum, and the acquired zero point time preceeding the present time is used as an acting reference zero point time. Needless to say that the following zero point time just before the close command or the open command may be used without the zero point evaluation process. Hereinbelow, the zero point time acquired by conducting the zero point evaluation process just before the close command or the open command and the zero point time just before the close command or the open command are referred to as a reference zero point time. As described, because the reference zero point time is detected, it is possible to acquire an accurate zero point of the interpole voltage and an accurate zero point of the main circuit current. An operation of the acting time prediction means 4 wavy will be described. As for the breaker 200, the close time and the open time under the reference environmental condition such as an environmental temperature and a control voltage, hereinbelow respectively referred to as a basic close time and a basic open time, and variation characteristics of the close time and the open time along with a change of the environmental condition are acquired and stored in the acting time prediction means 4 respectively as the basic close time table, the basic open time table, a close time correction table, and an open time correction table. A schematical structure of the correction tables is illustrated in Figure 4. Figure 4 (a) illustrates an entire structure of the correction tables. Figure 4 (b) illustrates a detail of the correction tables for calculating a correction amount under a certain environmental condition. Such a correction data are almost commonly owned by controlled switching devices of the same type because the controlled switching devices of the same type has a common characteristic. In the acting time prediction means 4, an estimated reference close time and an estimated reference open time respectively of estimated the values of the close time and the open time under the reference environmental condition are acquired by the observation close time, the observation open time and the environmental condition at an operating time respectively acquired by the acting time measuring means 41, the environmental temperature measuring means 42 and the control voltage measuring means 43, and a combination of the reference close time and the close time correction table or a combination of the reference open time and the open time correction table; and the reference close time and the reference open time are corrected by the estimated reference close time and the estimated reference open time; and a predicted close time and a predicted open time are obtained at a real time based on the corrected reference close time and the corrected reference open time, inputs from the acting time measuring means 41, the environmental temperature measuring means 42, and the control voltage measuring means 43, and the close time correction table or the open time correction table. Incidentally, the reference close time and the reference open time are served as predicting references of the close time and the open time under the reference environmental condition until a real time and obtained from time series data of the estimated reference close time and the estimated reference open time until a past acting time based on the basic close time and the basic open time. A process of obtaining the reference close time and the reference open time will be described in a latter part of this specification. Time correction data under an environmental condition X has a correction amount obtained from environmental temperatures until four point adjacent to the environmental condition X and time correction data corresponding to the control voltage in use of bidirectional first order interpolation. It is possible to accurately predict the close time and the open time of the breaker 200 by correcting the close time and the open time of the breaker 200 in response to the environmental condition. The reference close time and the reference open time are corrected by properly weighting each of the estimated reference close times and each of the estimated reference open times at acting times of past n times, for example 10 times. In other words, the estimated reference close times as much as n and the estimated reference open times as much as n are respectively powered by weight coefficients as much as n, properly selected so that a sum respectively of these becomes 1, and results are added to serve as a new reference close time and a new reference open time. It is desirable that weight coefficients for closer data are made large in order to enhance a response to evaluations of the reference close time and the reference open time. Incidentally, at time of starting to use the device, the basic close time is used as the reference close time and the estimated reference close time, and the basic open time is used as the reference open time and the estimated reference open time. When differences between the estimated reference close time and the reference close time and between the estimated reference open time and the reference open time are large for example ±2msec or more, it is preferable to omit such an estimated reference close time and such an estimated reference open time out of subjects for the correction. The correction of the reference close time and the reference open time is effective for aged deterioration of an operating time caused by mechanical wear. Progress of abrupt wear and so on of a sliding portion of a make break mechanism may be detected based on deviations between the estimated reference close time and the reference close time and between the estimated reference open time and the reference open time or deviations between the estimated reference close time and a prior estimated reference close time and between the estimated reference open time and a prior estimated reference open time. When changes of the close time and the open time along with the change of the environmental condition can be practically ignored, the correction is not conducted as above, and average values of the close times or of the open times respectively in a plurality of close operations or a plurality of open operations may be used respectively as the predicted close time and the predicted the open time. Although there has been described that the variations of the close time and the open time along with the change of the environmental conditions are corrected based on the environmental temperature and the control voltage, in a controlled switching device of an indirect operation type using a compression air or a hydroric oil as an operation medium, the close time and the open time may be corrected based on changes of a temperature and a pressure of operation medium. When the control signal output means 5 detects the close command or the open command, based on a detection time of the close command or the open command, the reference zero point time, and the predicted close time or the predicted open time, the control signal output means 5 acquires and sets the close control delay time and the open control delay time respectively for making at a predetermined interpole voltage phase in case of detecting the close command and for opening the pole at a predetermined main circuit current phase in case that the open command is detected. Thereafter, the device is started. The close control signal or the open control signal is outputted immediately after a lapse of the close control delay time and the open control delay time. In the breaker 200, making is conducted at the predetermined interpole voltage phase and opening is conducted at the predetermined main circuit current phase. Hereinbelow, operation of the control signal output means 5 will be described separately for close command detection and open command detection. [I] Detection of Make Command A difference between a make time and a close time, hereinbelow referred to as a pre-arc time, depends on an interpole voltage at the make time. Because the pre-arc time is determined by a withstand curve A stipulated by a traveling speed of the movable contact and a voltage wave form B of the interpole voltage as an absolute value, as shown in Figure 5, it is necessary to acquire the make time by subtracting the pre-arc time, obtained from a relationship between the withstand curve A and the voltage wave form B, from the predicted close time and to output the close control signal based on thus acquired make time in order to make the main circuit 100 at a predetermined interpole voltage phase. Figure 5 shows a case of making at an interpole voltage phase of 90°. An intersection between the withstand curve A and the interpole voltage wave form B is target make timing, i.e. a generation time of a pre-arc. Latency from the generation time to a point C, where the contact is made, is the pre-arc time. Hereinbelow, latency from the reference zero point time to the detection time of the close command is referred to as a close command detection time; latency from an interpole voltage zero point time just before making to the make time is referred to as a half period make time; a time obtained by adding the pre-arc time to the half period make time is referred to as a half period close time; a time obtained by subtracting the half period close time from the predicted close time is referred to as a predicted half period start time; and a time obtained by dividing the predicted close half period start time by the half period, by referring to K as an integer part of the obtained quoitent, by subtracting the predicted close half period start time from a power of the half period and K + 1 is referred to as a close command float time. In the control signal output means 5, the close command detection time is acquired from the reference zero point time and the close command detection time; the half period make time is acquired from a target make phase previously set; the pre-arc time is acquired from an interpole voltage at the target make phase; the half period close time is acquired from the half period make time and the pre-arc time; the predicted close half period start time is acquired from the predicted close time and the half period close time; and the close command float time is acquired from the half period and the predicted close half period start time. Because the pre-arc time depends on environmental conditions such as an environmental temperature, a control voltage and a pressure of an insurative gas and a traveling speed of the movable contact at time of making, the estimated reference close time may be corrected in a manner similar to those obtaining by the observation close time and the close time correction table. The close control delay time being a delay time until the close control signal is outputted is acquired based on a relationship of magnitude between the close time detection time and the close command float time. (1) When the close command detection time is smaller than the close command float time, a time obtained by subtracting the close command detection time from the close command float time is set to a delay timer and started as the close control delay time. The close control signal is outputted immediately after a lapse the close control delay time. (2) When the close command detection time is larger than the close command float time, a time obtained by adding the half period to the close command float time and succeedingly subtracting the close command detection time therefrom is set to the delay timer as the close control delay time. Thereafter, the device is started. The close control signal is outputted immediately after a lapse of the close control delay time. As described, the close control delay time does not exceed the half poriod. Further, there has been described on a premise that the close command detection time, the half period make time, the pre-arc time, the half period close time, the predicted close half period start time, the close command float time, and so on were acquired by the control signal output means 5 after detecting the close command. However, it is possible to minimize a delay of an output of the close control signal caused by a calculation time by constructing such that the half period make time, the pre-arc time, the half period close time, and the predicted close half period start time are previously acquired in a half period preceeding the detection of the close command; and after detecting the close command only the close command detection time is acquired; and immediately thereafter the close control delay time is acquired. Although there has been described a process from the detection of the close command to the output of the close control signal in use of the terminologies such as the close command detection time, the half period make time, the half period close time, the predicted close half period start time, and the close command float time, the terminologies have been used for convenience in explaining the present invention. It is needless to say that a purpose of the present invention is to constantly detect the reference zero point time, to start the delay timer, which determines timing for outputting the close control signal immediately after the close command is detected, and to make at a predetermined phase of the interpole voltage with respect to the close operation of the breaker, and a structure realizing this purpose is included in the present invention. In a case that a mechanical scattering does not exist in the acting time of the breaker, it is preferable to make the target make phase 0° when making is by a capacitor bank and 90° when making is by a shunt reactor. However, practically there is a scattering in a mechanical operation. For example, in case of making by the capacitor bank, because a making surge increases when an actual close time is shorter than predicted in comparison with an occasion that the actual close time is as much longer than predicted, it is possible to suppress a normal making surge by backward shifting the target make phase a little in response to the scattering of the mechanical operation. As described, since the controlled switching device is constructed so as to constantly detect the reference zero point time and to start the delay timer, which determines the output timing of the close control signal immediately after detecting the close command, it is possible to output the close control signal within a half period after detecting the close command and to rapidly close the breaker 200. [II] Detection of Open Command In order to cut off the main circuit current so as not to generate an abnormal voltage by a reignition or a restrike in the main circuit 100, the open control signal is generated as follows for opening the pole at a main circuit current phase, i.e. target open phase, by which the main circuit current is completed to cut off after a lapse of a predetermined arc time. Hereinbelow, for convenience of explanation, latency from the reference zero point time to the detection time of the open command is referred to as a open command detection time; a time subtracting a target arc-time from the half period is referred to as a half period open time, which corresponds to the target open phase; a time obtained by subtracting the half period open time from the predicted open time is referred to as a predicted open half period start time; and a time obtained by dividing the predicted open half period start time by the half period, by referring to K as an integer part of the obtained quotient, and by subtracting the predicted open half period start time from a power of the half period and K + 1 is referred to as an open command float time. In the control signal output means 5, the open command detection time is acquired from the reference zero point time and the open command detection time; the half period make time is acquired from the half period and a set arc-time; the predicted open half period start time is acquired from the predicted open time and the half period open time; and the open command float time is acquired from the half period and the predicted open half period start time. The open control delay time, which is latency until the open control signal is outputted, is acquired based on a relationship of magnitude between the open command detection time and the open command float time. (1) When the open command detection time is smaller than the open command float time, a time obtained by subtracting the open command detection time from the open command float time is set to a delay timer as the open control delay time, and the controlled switching device is started. The open control signal is outputted immediately after a lapse of the open control delay time. (2) When the open command detection time is larger than the open command float time, a time obtained by adding the half period to the open command float time and by subtracting the open command detection time therefrom is set to the delay timer as the open control delay time, and the controlled switching device is started. The open control signal is outputted immediately after a lapse of the open control delay time. As described, the open control delay time does not exceed the half period. Although there has been described on a proposition that the open command detection time, the half period open time, the predicted open half period start time, the open command float time, and so on were acquired by the control signal output means 5 after detecting the open command, it is possible to minimize a delay of starting the open operation caused by calculation by constructing the controlled switching device so that the half period open time is previously acquired and, after detecting the open command, only the open control delay time is acquired immediately after acquiring only the open command detection time. Although there has been described a process from the detection of the open command to the output of the open control signal in use of the terminologies such as the open command detection time, the half period open time, the predicted open half period start time, and the open command float time, these were used for convenience of explanation. A purpose of the present invention concerning the open operation of the breaker is to construct the controlled switching device so that the reference zero point time is constantly detected; and a delay timer for immediately determining output timing of the open control signal after detecting the open command is started so that the pole is opened at a predetermined phase of the main circuit current; and a structure achieving this purpose is included in the present invention. Embodiment 2 Figure 6 is a block chart of a controlled switching device according to Embodiment 2 of the present invention. Instead of the acting time measuring means 41 illustrated in Figure 1, an operating time measuring means 41a, which acquires the observation close time from a rise time of a current signal at time of closing pole, i.e. start time of pre-arc, acquired by a main circuit current measuring means 2, and from a close control signal is used. A structure of the acting time measuring means 41a will be described. At time of a close operation, a current signal D illustrated in Figure 7 is acquired from the main circuit current measuring means 2 at time of closing the pole. Because an unsuccessive portion occurs in the current signal D at a make time F, the make time F is detected as the start time of the pre-arc. At first, only a high-frequency component of the current signal D is taken out by a high-pass filter. The high-pass filter may be constructed by a digital filter for processing and calculating the current signal D, or by an analog filter for processing an analog signal from a power transformer (PT) and an a.d. converter for sequentially digitizing at predetermined sampling intervals. By previously setting a positive threshold value and a negative threshold value for an obtained high level signal E, a time when a value of the high level signal exceeds the threshold value using an output time of the close control signal. When the value exceeds the positive threshold value at first, a positive local peak point is further acquired and a time thereof is rendered to be the make time F. The positive local peak point designates a point n, at which E (n-1) ≦E (n) and E (n) ≧E (n-1) are established when 3 sequential voltage signal values of E (n-1) , E (n) , E (n+1) exist. Similarly, when the value exceeds the negative threshold value at first, a negative local peak time is further acquired and a time thereof is rendered to be the make time F. The negative local peak point designates a point n, at which E (n-1) ≧E (n) and E (n) ≦E (n+1) are established when there are three sequential signals E (n-1) , E (n) and E (n+1) . An observation close time is acquired such that latency between the output time of the close control signal and the make time acquired as in the above is added to the pre-arc time provided that the latency is acquired by subtracting the pre-arc time from the observation close time. Because the pre-arc time differs depending on a phase of the interpole voltage at time of making, it is necessary to acquire the interpole voltage phase at the time of making depending on a difference of thus acquired observation close time and the predicted close time and to acquire an effective pre-arc time at time of closing. According to this method, it is possible to measure the observation close time without using an auxiliary switch and other measuring means. Embodiment 3 Figure 8 is a block chart of a power make break switch according to Embodiment 3 of the present invention. A frequency detection means 31 for detecting frequencies of an interpole voltage and of a main circuit current from a reference zero point time, acquired by a zero point detection means 3, is provided in the controlled switching device illustrated in Figure 1, and a half period, which is basic information used in a control signal output means 5, is set based on the frequencies acquired by the frequency detection means 31. A structure of the frequency detection means 31 will be described. Because the frequency detection means 31 can be applied to both of the interpole voltage and the main circuit current, the frequency detection means 31 is not separately described with respect to the interpole voltage and the main circuit current. Provided that sequential two reference zero point times are t 1 and t 2 , a frequency at that time becomes 1/(t 1 -t 2 ). Frequencies are calculated for each reference zero point time. An average of continuous frequencies as much as n, for example values of hundred times, is rendered a reference frequency, and a half period of the reference frequency is acquired. Although the frequency does not abruptly vary, there is a case that a waveform hunts, an upper limit and a lower limit of the frequency are previously set in response to a system, and when the acquired reference frequency deviates out of a range of the upper limit and the lower limit, the deviated value is omitted in a process. Although embodiments of the present invention have been described on a premise that the breaker 200 is a single phase, it is needless to say that the above structure is applicable to a controlled switching device with three-phase individual operation by providing the above structure for each of the phases. The first advantage of the controlled switching device according to the present invention is that the close control signal is outputted after a wait time within a half cycle from detection of the close command, and it is possible to make at the target phase. The second advantage of the controlled switching device according to the present invention is that the zero point time to be detected becomes further accurate and an error of the interpole voltage phase at time of making from the target phase becomes further small. The third advantage of the controlled switching device according to the present invention is that an error of the interpole voltage phase at time of making from the target phase can be further reduced, which error is caused by a variation of the environmental condition. The fourth advantage of the controlled switching device according to the present invention is that an error, which is caused by aged deterioration, of the interpole voltage phase at time of making from the target phase can be further reduced. The fifth advantage of the controlled switching device according to the present invention is that the predicting close time can be further accurately corrected. The sixth advantage of the controlled switching device according to the present invention is that various time information, being a reference at time of closing the pole, becomes further accurate, and an error of the interpole voltage phase at time of making from the target phase can be further reduced. The seventh advantage of the controlled switching device according to the present invention is that the open control signal is outputted after a wait time within a half cycle from detection of the open command, and it is possible to open the pole at the target phase. The eighth advantage of the controlled switching device according to the present invention is that the zero point time to be detected becomes further accurate, and an error of the main circuit current phase at time of opening the pole from the target phase can be further reduced. The ninth advantage of the controlled switching device according to the present invention is that an error, which is caused by a variation of environmental condition, of the main circuit current phase at time of opening the pole from the target phase can be further reduced. The tenth advantage of the controlled switching device according to the present invention is that an error, which is caused by aged deterioration, of the main circuit current phase at time of opening the pole from the target phase can be further reduced. The eleventh advantage of the controlled switching device according to the present invention is that various time information, being a reference at time of opening the pole, becomes further accurate, and an error of the main circuit current phase at time of opening the pole from the target phase can be further reduced. Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

Claims: A method of closing a breaker (200) at a target make phase of an AC interpole voltage applied across poles of the breaker (200), wherein the target make phase is a target zero point of a voltage and a current measured from a position after a half cycle from a starting point in which a current starts to flow through a main circuit (100) by a close operation; said method using a device (300) comprising interpole voltage measuring means (1) for detecting an interpole voltage zero time point when the interpole voltage is instantaneously zero, based on measured interpole voltage; and control means (400) for output of a close control signal; said method characterized in that the interpole voltage measuring means (1) stores in a memory, over time, a plurality of detected interpole voltage zero time points; and the control means (400) predicts a predicted close time of the poles measured from the output of the close control signal to actual closing of the poles at a target close point; determines a close command detection time measured from the interpole voltage zero time point preceding and closest in time to a close command to receipt of the close command; obtains a pre-arc time measured from a target make phase to the actual closing at the target close point; determines a close control delay time from receipt of the close command until issue of the close command signal within one-half period of the interpole voltage; and outputs the close control signal after lapse of the close control delay time so that the making is completed at the target make phase. The method of closing a breaker (200) according to claim 1, characterized in that the control means (400) continuously evaluates the zero time points a number of times preceding and closest in time to receipt of the close command, and minimizes deviations with respect to each of the zero time points evaluated, from a product of one-half period of the interpole voltage and an integer, and selects the zero time point from times with the minimum sum of absolute values of the deviations just before the receipt of the close command and closest in time to the receipt of the close command. The method of closing a breaker (200) according to claim 1, characterised in that the control means (400) predicts the predicted close time by correcting a reference close time based on a reference environmental condition and a measured environmental condition by consulting a close time correction table for the environmental condition. The method of closing a breaker (200) according to claim 1, characterized in that the control means (400) comprises close time detection means for detecting time of closing of the switch poles; and operating time measuring means (41) for acquiring an observed close time from the close control signal until closing of the switch poles; and in that the control means (400) corrects its reference close time based on a measured environmental condition by consulting a close time correction table based on the environmental condition. The method of closing a breaker (200) according to claim 1, characterized in that the control means (400) detects a rise time of a main circuit current flowing at closing of the poles and including operating time measuring means (41) acquiring an observed close time by adding the pre-arc time to the delay from the output of the close control signal until the rise time of the main circuit current; and in that the control means (400) corrects a reference close time based on a measured environmental condition by consulting a close time correction table based on the environmental condition. The method of closing a breaker (200) according to claim 1, characterized in that the control means (400) uses a fixed number of continuous zero time points preceding and closest in time to receipt of the close command; acquires local frequencies of the interpole voltage from delays between adjacent zero time points; and determines a frequency of the interpole voltage as an average of the local frequencies. A method of breaking a breaker (200) actuated at a target open phase of an AC main circuit current flowing through the poles of the breaker (200), wherein the target open phase is a target zero point of a voltage and a current measured from a position after a half cycle from a starting point in which a current stops flowing through a main circuit by an open operation; said method using a device (300) comprising main circuit current measuring means (2) for measuring an AC main circuit current flowing through the poles of a breaker when closed, zero point time detecting means (3) for detecting an interpole current zero time point when current flowing through the breaker (200) is instantaneously zero, based on measured main circuit current and control means (400) for output of a close control signal; said method characterized in that the zero time point detection means (3) stores in a memory, over time, a plurality of detected interpole current zero time points; and the control means (400) predicts a predicted open time of the poles measured from the output of the open control signal to actual opening of the poles at the target phase; determines an open command detection time, measured from the main circuit current zero time point preceding and closest in time to an open command to receipt of the open command; determines an open control delay time within one-half period of the main circuit current; and outputs the open control signal after lapse of the open command detection time and the open control delay time so that circuit breaking is completed at the target open phase. The method of breaking a breaker (200) according to claim 7, characterized in that the control means (400) continuously evaluates the zero time points a number of times preceding and closest in time to receipt of the open command, minimizes deviations with respect to each of the zero time points evaluated from a product of one-half period of the main circuit current and an integer, and selects the main circuit current zero time point from times within the minimum sum of absolute values of the deviations just before receipt of the open command and closest in time to receipt of the open command. The method of breaking a breaker (200) according to claim 7, characterized in that the control means (400) predicts the predicted open time by correcting a reference open time based on a reference environmental condition and a measured environmental condition and consults an open time correction table for the environmental condition. The method of breaking a breaker (200) according to claim 7, characterized in that the control means (400) comprises open time detection means detecting time of opening of the switch poles; and operating time measuring means for acquiring an observed open time from the open time and output of the open control signal; and in that the control means (400) corrects a reference open time for a measured environmental condition by consulting an open time correction table based on the environmental condition. The method of breaking a breaker (200) according to claim 7, characterized in that the control means (400) uses a fixed number of continuous main circuit current zero time points preceding and closest in time to receipt of the open command; acquires local frequencies of the main circuit current from delays between adjacent main circuit current zero time points; and determines a frequency of the main circuit current of the breaker as an average of the local frequencies.

Inventors: HIRAI TAKASHI, TSUTADA HIROYUKI, HIRAI, TAKASHI, TSUTADA, HIROYUKI
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 2000
Main classification: H01H9
IPC codes: H01H33, H01H9