Abnormality detection device for three-phase power lines

Abstract

An object of the present invention is to obtain an abnormal detection device for three-phase electric wires with a simple circuit configuration that can easily confirm not only the presence or absence of disconnection in three electric wires (three-phase electric wires) through which driving power of a three-phase motor or the like flows, but also the presence or absence of abnormalities due to causes other than disconnection such as a rare short circuit. 【Solution means】 The present invention is a three-phase electric wire abnormal detection device 1 that detects abnormalities in three-phase electric wires L 1 , L 2 , L 3 by applying a DC voltage to the three-phase electric wires L 1 , L 2 , L 3 . The device includes a first terminal 41 connected to one polarity of a DC power supply 2 via voltage detection means 3, a second terminal 42 and a third terminal 43 connected to the other polarity via switching means 5 so that the electrical connection can be switched, a first short-circuit means 61 for short-circuiting between the first terminal 41 and the second terminal 42, a second short-circuit means 62 for short-circuiting between the second terminal 42 and the third terminal 43, a third short-circuit means 63 for short-circuiting between the third terminal 43 and the first terminal 41, and control means 7 for controlling the first short-circuit means 61 to the third short-circuit means 63 and the switching means 5 so that the third terminal 43 is electrically connected to the DC power supply 2 when the first terminal 41 and the second terminal 42 are short-circuited by the first short-circuit means 61, the second terminal 42 or the third terminal 43 is electrically connected to the DC power supply 2 when the second terminal 42 and the third terminal 43 are short-circuited by the second short-circuit means 62, and the second terminal 42 is electrically connected to the DC power supply 2 when the third terminal 43 and the first terminal 41 are short-circuited by the third short-circuit means 63. In the voltage detection means 3, the voltage [V 1 when the first terminal 41 and the third terminal 43 are conducting, detected when the first terminal 41 and the second terminal 42 are short-circuited by the first short-circuit means 61, the voltage [V 21 or the voltage [V 22 when the first terminal 41 and the third terminal 43 are conducting, detected when the second terminal 42 and the third terminal 43 are short-circuited by the second short-circuit means 62, and the voltage [V 3 when the first terminal 41 and the second terminal 42 are conducting, detected when the third terminal 43 and the first terminal 41 are short-circuited by the third short-circuit means 63 are compared. These three voltage values [V 1 , [V21 or V 22 , [V 3 and an abnormality determination means 8 for determining an abnormality when any one of the values of ]] is different from the other two values.

Description

Technical Field

[0001] The present invention relates to an abnormality detection device for three-phase electric wires for checking whether there are any abnormalities such as rare short circuits or disconnections in three electric wires through which drive power flows in an electromechanical device (for example, a concrete vibrator) using a three-phase motor or the like.

Background Art

[0002] The applicant has previously proposed a disconnection detection device according to Patent No. 7323245 as a disconnection detection device that can easily check the presence or absence of disconnection in three wires (three-phase electric wires) used for power supply of a three-phase motor or the like. This disconnection detection device is a disconnection detection device that detects the presence or absence of disconnection in the three-phase electric wires by applying a DC voltage between one wire of the three-phase electric wires in a state where each phase is short-circuited and the other two wires, and includes a first terminal connected to one polarity of a DC power supply, and a second terminal and a third terminal connected to the other polarity, and switch means for electrically connecting the second terminal and the DC power supply when the DC voltage is applied to the third terminal between the second terminal and the DC power supply, and current detection means for detecting the current flowing between the second terminal and the DC power supply are connected in series. According to this disconnection detection device, it is possible to immediately detect the presence or absence of disconnection in the three-phase electric wires by simply connecting the first terminal to the third terminal of this disconnection detection device to the three-phase electric wires in a state where each phase is short-circuited.

[0003] However, this disconnection detection device is only intended to detect the presence or absence of disconnection in the three-phase electric wires, and since it detects the presence or absence of disconnection depending on whether a closed circuit is formed by the three-phase electric wires and the disconnection detection device when the disconnection detection device is connected to the three-phase electric wires, it cannot detect abnormalities other than disconnection such as rare short circuits occurring in the coils of the stator of a three-phase motor. Also, even in disconnection detection, it is effective for a star-connected stator, but it cannot be detected in the case of a delta-connected stator.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent No. 7323245 [Disclosure of the Invention] [Problems to be Solved by the Invention]

[0005] An object of the present invention is to provide an abnormal detection device for three-phase electric wires with a simple circuit configuration that can easily confirm not only the presence or absence of disconnection in three electric wires (three-phase electric wires) through which driving power of a three-phase motor or the like flows, but also the presence or absence of abnormalities due to causes other than disconnection such as a rare short circuit. [Means for Solving the Problems]

[0006] The abnormal detection device for three-phase electric wires of the present invention is a three-phase electric wire abnormal detection device that applies a DC voltage to three-phase electric wires in a state where each phase is connected to detect abnormalities in the three-phase electric wires, and includes a first terminal connected to one polarity of a DC power supply via voltage detection means, a second terminal and a third terminal connected to the other polarity so that the electrical connection can be switched via switching means, a first short-circuit means for short-circuiting between the first terminal and the second terminal, a second short-circuit means for short-circuiting between the second terminal and the third terminal, a third short-circuit means for short-circuiting between the third terminal and the first terminal, control means for controlling the first short-circuit means to the third short-circuit means and the switching means so that the third terminal is electrically connected to the DC power supply when the first terminal - second terminal is short-circuited by the first short-circuit means, the second terminal or the third terminal is electrically connected to the DC power supply when the second terminal - third terminal is short-circuited by the second short-circuit means, and the second terminal is electrically connected to the DC power supply when the third terminal - first terminal is short-circuited by the third short-circuit means, and the voltage [V 1 between the first terminal and the third terminal when conducting detected by the voltage detection means when the first terminal - second terminal is short-circuited by the first short-circuit means, and the voltage [V 21 between the first terminal and the second terminal or the voltage [V 22and the voltage across the first terminal and the second terminal detected by the voltage detection means when the third terminal and the first terminal are short-circuited by the third short-circuit means [V 3 are compared, and when any one of these three voltage values [V 1 [V 21 or V 22 [V 3 is different from the other two values, an abnormality determination means for determining an abnormality is provided.

[0007] The voltage detection means may be configured to read the voltage across both ends by interposing a resistor or a current transformer between one polarity of the DC power supply and the first terminal.

[0008] The switching means may be any means that can switch a terminal electrically connected to the other polarity of the DC power supply to the second terminal or the third terminal. For example, a relay may be used, or a semiconductor switch (such as a transistor or a photocoupler) having an on-resistance smaller than the resistance value of the three-phase power line to be detected for the presence or absence of an abnormality may be used.

[0009] The first short-circuit means to the third short-circuit means may be any means that can short-circuit between each of the first terminal to the third terminal. For example, a relay may be used, or a semiconductor switch (such as a transistor or a photocoupler) having an on-resistance smaller than the resistance value of the three-phase power line to be detected for the presence or absence of an abnormality may be used.

[0010] The control means may be any means that can control the operations of the first short-circuit means to the third short-circuit means and the operation of the switching means so that when the first short-circuit means short-circuits between the first terminal and the second terminal, the third terminal is electrically connected to the DC power supply, when the second short-circuit means short-circuits between the second terminal and the third terminal, the second terminal or the third terminal is electrically connected to the DC power supply, and when the third short-circuit means short-circuits between the third terminal and the first terminal, the second terminal is electrically connected to the DC power supply. For example, a microcomputer programmed to execute such control may be used, or a circuit for performing such control may be used.

[0011] When there is a short circuit between the first terminal and the second terminal, the voltage [V 1 between the first terminal and the third terminal detected by the voltage detection means when the first terminal and the third terminal are conducting, and the voltage [V 21 between the first terminal and the second terminal detected by the voltage detection means when the second terminal and the third terminal are short-circuited or the voltage [V 22 between the first terminal and the third terminal when they are conducting, and the voltage [V 3 between the first terminal and the second terminal detected by the voltage detection means when there is a short circuit between the third terminal and the first terminal. If it is possible to output an abnormal signal when any one of the three voltage values is different from the other two values, it is possible to use a microcomputer.

Advantages of the Invention

[0012] According to the present invention, by simply connecting the first to third terminals of the three-phase power line abnormality detection device to the three-phase power line respectively, it is possible to easily confirm the presence or absence of an abnormality in the three-phase power line. That is, in the present invention, in a three-phase power line abnormality detection device that applies a DC voltage to a three-phase power line in a state where each phase is connected to detect an abnormality in the three-phase power line, a first terminal connected to one polarity of a DC power supply via voltage detection means, a second terminal and a third terminal connected so that the electrical connection can be switched via switching means to the other polarity, a first short-circuit means for short-circuiting between the first terminal and the second terminal, a second short-circuit means for short-circuiting between the second terminal and the third terminal, a third short-circuit means for short-circuiting between the third terminal and the first terminal, and control means for controlling the first to third short-circuit means and the switching means so that the third terminal is electrically connected to the DC power supply when the first terminal and the second terminal are short-circuited by the first short-circuit means, the second terminal or the third terminal is electrically connected to the DC power supply when the second terminal and the third terminal are short-circuited by the second short-circuit means, and the second terminal is electrically connected to the DC power supply when the third terminal and the first terminal are short-circuited by the third short-circuit means. Therefore, using this control means, when the first terminal and the second terminal are short-circuited by the first short-circuit means, the third terminal can be electrically connected to the DC power supply, when the second terminal and the third terminal are short-circuited by the second short-circuit means, the second terminal or the third terminal can be electrically connected to the DC power supply, and when the third terminal and the first terminal are short-circuited by the third short-circuit means, the second terminal can be electrically connected to the DC power supply in sequence to apply a DC voltage to the three-phase power line.

[0013] And the voltage [V 1 when the first terminal and the third terminal are conducting, detected by the voltage detection means when the first terminal and the second terminal are short-circuited by the first short-circuit means, 21 or the voltage [V 22 when the first terminal and the third terminal are conducting, detected by the voltage detection means when the second terminal and the third terminal are short-circuited by the second short-circuit means, 3 and the voltage [V 1 detected by the voltage detection means when the third terminal and the first terminal are short-circuited by the third short-circuit means are compared, and these three voltage values [V 21 or V 22 , [V3 Since it is provided with an abnormality determination means for determining an abnormality when any one of the values is different from the other two values, if an abnormality such as a rare short circuit or disconnection occurs in any of the electric wires constituting the three-phase electric wire, this can be detected.

[0014] That is, for the three-phase electric wire used in a three-phase motor or the like, usually, three electric wires having substantially the same resistance value are used. When there is no abnormality in any of these three electric wires, there is no fluctuation in the resistance values of these three electric wires. Therefore, the voltage between the first terminal and the third terminal when the first terminal and the second terminal are short-circuited, which is detected by the voltage detection means [V 1 and the voltage between the first terminal and the second terminal when the second terminal and the third terminal are short-circuited [V 21 or the voltage between the first terminal and the third terminal [V 22 and the voltage between the first terminal and the second terminal when the third terminal and the first terminal are short-circuited [V 3 are all substantially the same value, and no abnormality is determined by the abnormality determination means. On the other hand, when an abnormality occurs in any of the three electric wires, a fluctuation occurs in the resistance value of any of the electric wires in which the abnormality has occurred. Therefore, the voltage between the first terminal and the third terminal when the first terminal and the second terminal are short-circuited, which is detected by the voltage detection means [V 1 , the voltage between the first terminal and the second terminal when the second terminal and the third terminal are short-circuited [V 21 or the voltage between the first terminal and the third terminal [V 22 , the voltage between the first terminal and the second terminal when the third terminal and the first terminal are short-circuited [V 3 becomes a value different from the other values, and an abnormality is determined by the abnormality determination means.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiment for Carrying Out the Invention

[0016] Figure 1 is a circuit diagram showing the outline of the three - phase electric wire abnormality detection device 1 of this invention. The three - phase electric wire abnormality detection device 1 includes a first terminal 41 connected to the cathode side of a DC power supply 2 via a resistor 3, and a second terminal 42 and a third terminal 43 connected to the anode side via a relay 5 so that the electrical connection can be switched. Between the first terminal 41 and the second terminal 42, there is a relay 61 which is the first short - circuit means for short - circuiting between the first terminal 41 and the second terminal 42. Between the second terminal 42 and the third terminal 43, there is a relay 62 which is the second short - circuit means for short - circuiting between the second terminal 42 and the third terminal 43. Between the third terminal 43 and the first terminal 41, there is a relay 63 which is the third short - circuit means for short - circuiting between the third terminal 43 and the first terminal 41. Each of them is arranged. A microcomputer 7 is connected to the relay 5 and the relays 61 to 63, and an A / D converter 8 is connected to the resistor 3. The A / D converter 8 is connected to the microcomputer 7. Note that the A / D converter 8 may be built into the microcomputer 7. Also, a display means 9 (light - emitting diode) for indicating whether the state of the three - phase electric wire is normal or not is connected to the microcomputer 7.

[0017] The microcomputer 7 has a function as a control means for controlling the operation of a relay 5 which is a switching means for switching the electrical connection to the DC power supply 2 to the second terminal 42 or the third terminal 43, and the operations of relays 61 to 63 which are means for short-circuiting between the respective terminals of the first terminal 41 to the third terminal 43. When the relay 61 shorts the first terminal 41 - the second terminal 42, the third terminal 43 is connected to the DC power supply 2. When the relay 62 shorts the second terminal 42 - the third terminal 43, the second terminal 42 or the third terminal 43 is connected to the DC power supply 2. When the relay 63 shorts the third terminal 43 - the first terminal 41, the second terminal 42 is connected to the DC power supply 2. A program for controlling the operation of the relay 5 and the operations of the relays 61 to 63 is stored so that this is the case.

[0018] In this embodiment, the operations of the relay 5 and the relays 61 to 63 are controlled by a control program stored in the microcomputer 7. However, the operations of the relay 5 and the relays 61 to 63 can also be controlled by using a counter and a ROM instead of the control program. For example, the counter 72, the relay 5, and the relays 61 to 63 are connected to a ROM 71 in which the combination of relays to be turned on in advance is written. By changing the address of the ROM 71 with the counter 72, the operations of the relay 5 and the relays 61 to 63 can be controlled (FIG. 2). In the example of FIG. 2, the relay 5 is connected to the third terminal 43 in the off state and is switched to be connected to the second terminal 42 when it is turned on. By switching the address of the ROM 71 in the order of 001, 002, 003 with the counter 72, the relay 5 and the relays 61 to 63 are controlled. When it is desired that the third terminal 43 be electrically connected to the DC power supply 2 when the relay 62 shorts the second terminal 42 - the third terminal 43, “relay 62” may be written as the “relay to be turned on” at the address 002 of the ROM 71.

[0019] The A / D converter 8 converts the three voltage values detected by the resistor 3, namely, (1) the voltage value [V 1 between the first terminal 41 and the third terminal 43 that conducts when the first terminal 41 and the second terminal 42 are short-circuited by the relay 61, (2) the voltage value [V 21 between the first terminal 41 and the second terminal 42 or the voltage value [V 22 between the first terminal 41 and the third terminal 43 that conducts when the second terminal 42 and the third terminal 43 are short-circuited by the relay 62, and (3) the voltage value [V 3 between the first terminal 41 and the second terminal 42 that conducts when the third terminal 43 and the first terminal 41 are short-circuited by the relay 63 into digital signals and outputs them to the microcomputer 7.

[0020] The microcomputer 7 compares (1) the voltage [V 1 between the first terminal and the third terminal when conducting, detected by the voltage detection means when the first terminal and the second terminal are short-circuited by the first short-circuit means, (2) the voltage [V 21 between the first terminal and the second terminal when conducting, detected by the voltage detection means when the second terminal and the third terminal are short-circuited by the second short-circuit means or the voltage [V 22 between the first terminal and the third terminal when conducting, and (3) the voltage [V 3 between the first terminal and the second terminal when conducting, detected by the voltage detection means when the third terminal and the first terminal are short-circuited by the third short-circuit means. When any one of these three voltage values [V 1 , [V 21 or V 22 , [V 3 is different from the other two values, it also has a function as an abnormality determination means for determining an abnormality. It compares the three voltage values output as digital signals from the A / D converter 8. When any one voltage value is different from the other two voltage values, it outputs an abnormality signal, and when the three voltage values are substantially the same, it outputs a normal signal to the display means 9 respectively, and the determination result is displayed on the display means 9.

[0021] Figure 3 shows the three-phase wire abnormality detection device 1 with the three wires L D of the delta-connected three-phase motor M 1 in a state where no driving power is supplied 2 and L 3It is a diagram showing a state of detecting the presence or absence of an abnormality by connecting to it. The first terminal 41 of the three-phase wire abnormality detection device 1 is the wire L of the three-phase motor M D at the intersection of 1 the wires L 3 The second terminal 42 is at the intersection of the wires L 1 the wires L 2 The third terminal 43 is at the intersection of the wires L 2 the wires L 3 respectively, and is connected to the three-phase wires L 1 the wires L 2 the wires L 3 at the intersection of the wires L

[0022] When the three-phase wire abnormality detection device 1 is operated in this state, the program stored in the microcomputer 7 is started, and the control of the operations of the relay 5 and the relays 61 to 63 is started. That is, first, the relay 61 is operated to short-circuit between the first terminal 41 and the second terminal 42, and the relay 5 is operated to electrically connect the third terminal 43 to the DC power supply 2. As a result, with the first terminal 41 - the second terminal 42 short-circuited, the first terminal 41 and the third terminal 43 are conducted through the three-phase wires L 1 the wires L 2 the wires L 3 and the DC voltage of the DC power supply 2 is applied. Then, the voltage [V 1 at the time of conduction between the first terminal and the third terminal in the short-circuit state between the first terminal and the second terminal is detected in the resistor 3 disposed between the DC power supply 2 and the first terminal 41, and the voltage value [V 1 is converted into a digital signal by the A / D converter 8 and stored in the microcomputer 7. Next, the relay 62 is operated to short-circuit between the second terminal 42 and the third terminal 43, and the relay 5 is operated to electrically connect the third terminal 43 to the DC power supply 2. As a result, with the second terminal 42 - the third terminal 43 short-circuited, the first terminal 41 and the third terminal 43 are conducted through the three-phase wires L 1 the wires L 2 the wires L 3 and the DC voltage of the DC power supply 2 is applied. Then, the voltage [V 22 at the time of conduction between the first terminal and the third terminal in the short-circuit state between the second terminal and the third terminal is detected in the resistor 3, and the voltage value [V 22is converted into a digital signal by the A / D converter 8 and stored in the microcomputer 7. Further, the relay 63 is operated to short-circuit between the third terminal 43 and the first terminal 41, and the relay 5 is operated to electrically connect the second terminal 42 to the DC power supply 2. As a result, the first terminal 41 and the second terminal 42 are conducted through the three-phase power lines L 1 、L 2 、L 3 while the third terminal 43 and the first terminal 41 are short-circuited, and the DC voltage of the DC power supply 2 is applied. Then, the voltage [V 3 at the time of conduction between the first terminal and the second terminal in the short-circuit state between the third terminal and the first terminal is detected in the resistor 3, and the voltage value [V 3 is converted into a digital signal by the A / D converter 8 and stored in the microcomputer 7. Finally, in the microcomputer 7, the three voltage values [V 1 , [V 22 , [V 3 stored as digital signals are compared. If any one of these voltage values is different from the other voltage values, an abnormal signal is output to the display means 9 to turn on the light-emitting diode in red, informing that an abnormality has occurred in the three-phase power lines. On the other hand, when the three voltage values [V 1 , [V 22 , [V 3 compared by the microcomputer 7 are substantially the same, a normal signal is output to the display means 9 to turn on the light-emitting diode in green, informing that the three-phase power lines are normal. Note that the program for controlling the operations of the relay 5 and the relays 61 to 63 can use a program that operates the relay 5 so that the second terminal 42 is electrically connected to the DC power supply 2 instead of the program part that operates the relay 5 so that the third terminal 43 is electrically connected to the DC power supply 2 when the second terminal 42 and the third terminal 43 are short-circuited by the relay 62. In this case, the first terminal 41 and the second terminal 42 are conducted through the three-phase power lines L 1 、L 2 、L 3 while the second terminal 42 and the third terminal 43 are short-circuited, and the voltage of the DC power supply 2 is applied, and the voltage [V 21is digitally converted by the A / D converter 8 and stored in the microcomputer 7, and compared with other voltage values [V 1 , [V 3 to determine the presence or absence of an abnormality.

[0023] Figure 4 shows the first terminal 41, the second terminal 42, the third terminal 43 of the three-phase wire abnormality detection device 1, the relay 61 (first short-circuit means), the relay 62 (second short-circuit means), the relay 63 (third short-circuit means), and the delta-connected three-phase wire L 1 , L 2 , L 3 and is a circuit diagram showing the connection relationship therebetween. Using this figure, the voltage [V 1 at the time of conduction between the first terminal and the third terminal when there is a short circuit between the first terminal and the second terminal, which is detected by the resistor 3, and the voltage [V 22 at the time of conduction between the first terminal and the third terminal when there is a short circuit between the second terminal and the third terminal or the voltage [V 21 at the time of conduction between the first terminal and the second terminal, and the voltage [V 3 at the time of conduction between the first terminal and the second terminal when there is a short circuit between the third terminal and the first terminal are all substantially the same value under normal conditions, while one of the voltage values becomes significantly different from the other two voltage values under abnormal conditions.

[0024] For three-phase wires used in a three-phase motor or the like, usually three wires with substantially the same resistance value are used. Therefore, the resistances R D of the three-phase wires L 1 , L 2 , L 3 of the delta-connected three-phase motor M 1 , R 2 , R 3 are all the same resistance value R. In this circuit, when the relay 61 (first short-circuit means), the relay 62 (second short-circuit means), and the relay 63 (third short-circuit means) are individually operated to short-circuit between the respective terminals, the resistance between the first terminal 41 and the second terminal 42 and the resistance between the first terminal 41 and the third terminal are the three-phase wires L 1 , L 2 , L 3When there is no abnormality, it will be as shown in Table 1. When there is an abnormality such as a rare short circuit (let the resistance value of the wire with the rare short circuit be i) or a disconnection (let the resistance value of the wire with the disconnection be ∞) in any of the wires, it will be as shown in Table 2-1 and Table 2-2 (during rare short circuit), Table 3-1 and Table 3-2 (during disconnection).

[0025] That is, for the three-phase wires L 1 、L 2 、L 3 when there is no abnormality, as shown in Table 1, in the combination of the three resistance values of the resistance value between the first terminal 41 and the second terminal 42 when the relay 62 (the second short-circuit means) operates, the resistance value between the first terminal 41 and the second terminal 42 when the relay 63 (the third short-circuit means) operates, and the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (the first short-circuit means) operates (hereinafter referred to as "combination pattern A"), all the resistance values become R / 2 and match. Also, in the combination of the three resistance values of the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (the first short-circuit means) operates, the resistance value between the first terminal 41 and the third terminal 43 when the relay 62 (the second short-circuit means) operates, and the resistance value between the first terminal 41 and the second terminal 42 when the relay 63 (the third short-circuit means) operates (hereinafter referred to as "combination pattern B"), all the resistance values also become R / 2 and match.

Table 1

[0026] On the other hand, when there is an abnormality in any of the three-phase wires L 1 、L 2 、L 3 in either combination pattern A or combination pattern B, any one of the three resistance values will be different from the other two resistance values. For example, for wire L 1When a rare short occurs, in combination pattern A, only the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (first short-circuit means) operates is R / 2, which is different from the other two resistance values (Ri / (R + i)). Also in combination pattern B, only the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (first short-circuit means) operates is R / 2, which is different from the other two resistance values (Ri / (R + i)) (Table 2-1). Further, when a rare short occurs in any two of the three-phase power lines L 1 、L 2 、L 3 , in both combination pattern A and combination pattern B, any one of the three resistance values will be different from the other two resistance values. For example, when a rare short occurs in the power lines L 1 、L 2 , in combination pattern A, only the resistance value between the first terminal 41 and the second terminal 42 when the relay 63 (third short-circuit means) operates is i / 2, which is different from the other two resistance values (Ri / (R + i)). Also in combination pattern B, only the resistance value between the first terminal 41 and the second terminal 42 when the relay 63 (third short-circuit means) operates is i / 2, which is different from the other two resistance values (Ri / (R + i)) (Table 2-2). Note that when rare shorts occur in all of the three-phase power lines L 1 、L 2 、L 3 , in both combination pattern A and combination pattern B, all three resistance values will be 0.

Table 2-1

Table 2-2

[0027] Power line L 2When there is a disconnection in the wire, in combination pattern A, only the resistance value between the first terminal 41 and the second terminal 42 when the relay 62 (second short-circuit means) operates is R / 2, which is different from the other two resistance values of R. Also, in combination pattern B, only the resistance value between the first terminal 41 and the third terminal 43 when the relay 62 (second short-circuit means) operates is R / 2, which is different from the other two resistance values of R (Table 3-1). Further, for the two wires L 2 and L 3 when there is a disconnection, in combination pattern A, only the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (first short-circuit means) operates is ∞, which is different from the other two resistance values of R. Also, in combination pattern B, only the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (first short-circuit means) operates is ∞, which is different from the other two resistance values of R (Table 3-2). Note that when there is a disconnection in all three-phase wires L 1 and L 2 and L 3 , in both combination pattern A and combination pattern B, all three resistance values become ∞.

Table 3-1

Table 3-2

[0028] Therefore, for either combination pattern A or combination pattern B, by determining whether all three resistance values are the same or whether any one resistance value is different from the other two, it is possible to confirm whether the three-phase wires L 1 and L 2 and L 3 are in a normal state. And since the resistance value can be detected and calculated from the voltage, the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (first short-circuit means) operates is the conduction voltage [V 1As the resistance value between the first terminal 41 and the third terminal 43 when the relay 62 (second short - circuit means) operates, it is the conduction voltage [V] between the first terminal 41 and the third terminal 43 when the second terminal 42 and the third terminal 43 are short - circuited 22 As the resistance value between the first terminal 41 and the second terminal 42 when the relay 63 (third short - circuit means) operates, it is the conduction voltage [V] between the first terminal 41 and the second terminal 42 when the third terminal 43 and the first terminal 41 are short - circuited 3 As the resistance value between the first terminal 41 and the second terminal 42 when the relay 62 (second short - circuit means) operates, it is the conduction voltage [V] between the first terminal 41 and the second terminal 42 when the second terminal 42 and the third terminal 43 are short - circuited 21 As such, it can be detected by the resistor 3 respectively. And in the case of the combination pattern A, (1) the conduction voltage [V] between the first terminal and the third terminal when the first terminal and the second terminal are short - circuited 1 and (2) the conduction voltage [V] between the first terminal and the second terminal when the second terminal and the third terminal are short - circuited 21 and (3) the conduction voltage [V] between the first terminal and the second terminal when the third terminal and the first terminal are short - circuited 3 are compared, and by determining whether all three voltage values match or whether any one is significantly different from the other two, it is possible to confirm whether the three - phase power lines L 1 、L 2 、L 3 are in a normal state. In the case of the combination pattern B, (1) the conduction voltage [V] between the first terminal and the third terminal when the first terminal and the second terminal are short - circuited 1 and (2) the conduction voltage [V] between the first terminal and the third terminal when the second terminal and the third terminal are short - circuited 22 and (3) the conduction voltage [V] between the first terminal and the second terminal when the third terminal and the first terminal are short - circuited 3 are compared, and by determining whether all three voltage values match or whether any one is different from the other two, it is possible to confirm whether the three - phase power lines L 1 、L 2 、L 3 are in a normal state.

[0029] Note that for the three - phase power lines L 1 、L 2 、L 3If a rare short occurs in all of them, there is no difference in resistance value in either combination pattern A or combination pattern B. Therefore, depending on this embodiment, it is not possible to confirm whether the three-phase power lines L 1 、L 2 、L 3 are in a normal state. However, if all of the three-phase power lines L 1 、L 2 、L 3 are disconnected, when the three-phase power line abnormality detection device 1 is connected to the three-phase power lines L 1 、L 2 、L 3 and operated, no current flows and the light-emitting diode of the display means 9 does not light up. Therefore, it can be recognized that some abnormality has occurred.

[0030] FIG. 5 is a diagram showing a state in which the three-phase power line abnormality detection device 1 is connected to the three wires L S of the star-connected three-phase motor M 1 、L 2 、L 3 in a non-operating state to detect the presence or absence of an abnormality. The first terminal 41, the second terminal 42, and the third terminal 43 of the three-phase power line abnormality detection device 1 are connected to the three-phase power lines L 1 、L 2 、L 3 respectively. The operation when the three-phase power line abnormality detection device 1 is operated in this state is the same as when it is connected to and operated on the three wires L D of the delta-connected three-phase motor M 1 、L 2 、L 3 .

[0031] FIG. 6 is a circuit diagram showing the connection relationship between the first terminal 41, the second terminal 42, the third terminal 43 of the three-phase power line abnormality detection device 1, the relays 61 (first short-circuit means), 62 (second short-circuit means), 63 (third short-circuit means), and the star-connected three-phase power lines L 1 、L 2 、L 3 . Using this figure, the voltage [V 1and the conduction voltage [V] between the first terminal and the second terminal when the second terminal and the third terminal are short-circuited 21 or the conduction voltage [V] between the first terminal and the third terminal 22 and the conduction voltage [V] between the first terminal and the second terminal when the third terminal and the first terminal are short-circuited 3 Normally, all of these values are approximately the same, while in case of abnormality, one of the voltage values becomes significantly different from the other two voltage values.

[0032] Star-connected three-phase motor M S The three-phase power lines L 1 L 2 L 3 The resistances R 1 R 2 R 3 Even if there are resistances in the three-phase power lines L 1 L 2 L 3 their resistance values are all the same resistance value R. In this circuit, when the relay 61 (the first short-circuit means), the relay 62 (the second short-circuit means), and the relay 63 (the third short-circuit means) are each operated to short-circuit between the terminals, the resistance value between the first terminal 41 and the second terminal 42 and the resistance value between the first terminal 41 and the third terminal are as shown in Table 4 when there is no abnormality in the three-phase power lines L

[0033] That is, for the three-phase power lines L 1 L 2 L 3When there is no abnormality, as shown in Table 4, in the combination of three resistance values (combination pattern A) of the resistance value between the first terminal 41 and the second terminal 42 when the relay 62 (second short-circuit means) operates, the resistance value between the first terminal 41 and the second terminal 42 when the relay 63 (third short-circuit means) operates, and the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (first short-circuit means) operates, all the resistance values match at (3 / 2)R. Also, in the combination of three resistance values (combination pattern B) of the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (first short-circuit means) operates, the resistance value between the first terminal 41 and the third terminal 43 when the relay 62 (second short-circuit means) operates, and the resistance value between the first terminal 41 and the second terminal 42 when the relay 63 (third short-circuit means) operates, all the resistance values also match at (3 / 2)R.

Table 4

[0034] On the other hand, for any one of the three-phase power lines L 1 、L 2 、L 3 if there is an abnormality, in the combination of the three resistance values in the above two patterns, any one of the three resistance values in each pattern will be different from the other two resistance values. For example, if there is a rare short circuit in the power line L 1 in combination pattern A, only the resistance value between the first terminal 41 and the second terminal 42 when the relay 62 (second short-circuit means) operates is (i+(R / 2)), which is different from the other two resistance values ((Ri / (R+i))+R). Also, in combination pattern B, only the resistance value between the first terminal 41 and the third terminal 43 when the relay 62 (second short-circuit means) operates is (i+(R / 2)), which is different from the other two resistance values ((Ri / (R+i))+R) (Table 5-1). Also, for any two of the three-phase power lines L 1 、L 2 、L 3 if there is a rare short circuit, in both combination pattern A and combination pattern B, any one of the three resistance values will be different from the other two resistance values. For example, for the power line L1 and L 2 if a rare short circuit occurs in L, in combination pattern A, only the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (first short - circuit means) operates is ((i / 2)+R), which is different from the other two resistance values ((Ri / (R + i))+i). Also, in combination pattern B, only the resistance value between the first terminal 41 and the third terminal 43 when the relay 61 (first short - circuit means) operates is ((i / 2)+R), which is different from the other two resistance values ((Ri / (R + i))+i) (Table 5 - 2). Note that for the three - phase power lines L 1 and L 2 and L 3 if rare short circuits occur in all of them, in both combination pattern A and combination pattern B, all three resistance values become 0.

Table 5 - 1

Table 5 - 2

[0035] If the power line L 2 is open - circuited, in combination pattern A, only the resistance value between the first terminal 41 and the second terminal 42 when the relay 63 (third short - circuit means) operates is ∞, which is significantly different from the other two resistance values 2R. Also, in combination pattern B, only the resistance value between the first terminal 41 and the second terminal 42 when the relay 63 (third short - circuit means) operates is ∞, which is significantly different from the other two resistance values 2R (Table 6 - 1). On the other hand, in the case of star connection, if open - circuits occur in multiple power lines of the three - phase power lines, in both combination pattern A and combination pattern B, all three resistance values become ∞.

Table 6 - 1

Table 6 - 2

[0036] Therefore, for any of the combination patterns A and B, by determining whether all three resistance values match or any one resistance value is different from the other two, it is possible to check whether the three-phase power lines L 1 、L 2 、L 3 are in a normal state. And since the resistance value can be detected and calculated by detecting the voltage, the resistance value of the resistance between the first terminal 41 and the third terminal 43 when the relay 61 (the first short-circuit means) operates is the conduction voltage [V 1 between the first terminal 41 and the third terminal 43 when the first terminal 41 and the second terminal 42 are short-circuited by the relay 61, the resistance value of the resistance between the first terminal 41 and the third terminal 43 when the relay 62 (the second short-circuit means) operates is the conduction voltage [V 22 between the first terminal 41 and the third terminal 43 when the second terminal 42 and the third terminal 43 are short-circuited by the relay 62, the resistance value of the resistance between the first terminal 41 and the second terminal 42 when the relay 63 (the third short-circuit means) operates is the conduction voltage [V 3 between the first terminal 41 and the second terminal 42 when the third terminal 43 and the first terminal 41 are short-circuited by the relay 63, the resistance value of the resistance between the first terminal 41 and the second terminal 42 when the relay 62 (the second short-circuit means) operates is the conduction voltage [V 21 between the first terminal 41 and the second terminal 42 when the second terminal 42 and the third terminal 43 are short-circuited by the relay 62, and each is detected at the resistor 3. In the case of the combination pattern A, (1) the conduction voltage [V 1 between the first terminal and the third terminal when the first terminal and the second terminal are short-circuited, (2) the conduction voltage [V 21 between the first terminal and the second terminal when the second terminal and the third terminal are short-circuited, and (3) the conduction voltage [V 3 between the first terminal and the second terminal when the third terminal and the first terminal are short-circuited are compared. In the case of the combination pattern B, (1) the conduction voltage [V 1 between the first terminal and the third terminal when the first terminal and the second terminal are short-circuited, (2) the conduction voltage [V 22 between the first terminal and the third terminal when the second terminal and the third terminal are short-circuited, and (3) the conduction voltage [V 3By comparing them and determining whether all three voltage values in each pattern match or whether any one of them is different from the other two, it is possible to confirm whether the three-phase power lines L 1 、L 2 、L 3 are in a normal state.

[0037] Note that even in the case of a star connection, if a rare short circuit occurs in all of the three-phase power lines L 1 、L 2 、L 3 , no difference in resistance value will occur in either combination pattern A or combination pattern B. Therefore, depending on this embodiment, it is not possible to confirm whether the three-phase power lines L 1 、L 2 、L 3 are in a normal state. Also, if a plurality of the three-phase power lines L 1 、L 2 、L 3 are disconnected, even if the three-phase power line abnormality detection device 1 is connected to the three-phase power lines L 1 、L 2 、L 3 and operated, no current will flow and the light-emitting diode of the display means 9 will not light up. Therefore, it can be recognized that some abnormality has occurred.

Industrial Applicability

[0038] This invention relates to an abnormality detection device for three-phase power lines for confirming whether abnormalities such as rare short circuits or disconnections have occurred in three power lines through which drive power flows in electromechanical appliances using three-phase motors or the like, and has industrial applicability.

Explanation of Signs

[0039] 1 Abnormality detection device for three-phase power lines 2 DC power supply 3 Resistor (voltage detection means) 41 First terminal 42 Second terminal 43 Third terminal 5 Relay (switching means) 61 Relay (First short - circuit means) 62 Relay (Second short - circuit means) 63 Relay (Third short - circuit means) 7 Microcomputer (Control means, abnormality determination means) 71 ROM 72 Counter 8 A / D Converter 9 Display means L 1 、L 2 、L 3 Electric wire

Claims

[Claim 1] 1. A three-phase electric wire abnormality detection device that applies a DC voltage to a three-phase electric wire in a state in which each phase is connected to each other to detect an abnormality in the three-phase electric wire, a first terminal connected to one polarity of a DC power supply via a voltage detection means, and a second terminal and a third terminal connected to the other polarity via a switching means so that an electrical connection can be switched; a first short-circuiting means for short-circuiting between the first terminal and the second terminal, a second short-circuiting means for short-circuiting between the second terminal and the third terminal, and a third short-circuiting means for short-circuiting between the third terminal and the first terminal; a control means for controlling the first short-circuiting means through the third short-circuiting means and the switching means so that the third terminal is electrically connected to the DC power source when the first terminal and the second terminal are short-circuited by the first short-circuiting means, the second terminal or the third terminal is electrically connected to the DC power source when the second terminal and the third terminal are short-circuited by the second short-circuiting means, and the second terminal is electrically connected to the DC power source when the third terminal and the first terminal are short-circuited by the third short-circuiting means; A first terminal-third terminal conduction voltage value [V １ ], and a first terminal-second terminal conduction voltage value [V ２１ ] or the voltage value when the first terminal - the third terminal are conductive [V ２２ ], and a first terminal-second terminal conduction voltage value [V ３ ] and compare these three voltage values ​​[V １ ], [V ２１ Or V ２２ ], [V ３ and an abnormality determination means for determining that an abnormality has occurred when any one of the values ​​of the above is different from the other two values. An abnormality detection device for three-phase electric wires.

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