JPH0617084Y2 - Disconnection detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a wire breakage detection device for detecting wire breakage.

[Prior Art] Conventionally, various sensors such as a proximity switch, a micro switch, and a photoelectric switch are attached to a mechanical device, and in many cases, the lead wire of the sensor is directly or through a connector to the mechanical device. It has been extended to a control panel that contains a sequencer that controls the. If this lead wire is broken for any reason, it will be a serious obstacle in controlling the mechanical device.

Therefore, conventionally, as a disconnection detecting device for detecting disconnection of a lead wire, a device which detects disconnection of the lead wire by detecting a change in current flowing through the disconnection lead wire has been developed.

[Problems to be Solved by the Invention] However, although the above device can detect the disconnection of the lead wire, it does not have a function of compensating the current path to the sensor which is interrupted by the disconnection. In other words, even if a wire break is detected, the sensor cannot operate when the wire breaks, so the machine must be stopped to repair the wire break. It was often an obstacle.

For this reason, there has been a demand for a wire breakage detection device capable of detecting wire breakage for a long time and compensating for the detection operation of the sensor at the time of wire breakage.

Therefore, the present invention has been made for the purpose of providing a disconnection detecting device capable of detecting disconnection of an electric wire and compensating the operation of a device such as a sensor.

[Means for Solving the Problem] That is, the present invention made in order to achieve the above-mentioned object is the disconnection for detecting the disconnection of an electric wire for supplying a direct current to a device from a predetermined power source. A detector, which has a bypass wire provided in parallel with the electric wire and a PN junction structure, in which the terminal connected to the P-type semiconductor is the power source side and the terminal connected to the N-type semiconductor is the device. Side, the semiconductor element connected in series to the bypass line, ground resistance means provided on the equipment side of the bypass line from the semiconductor element, and connecting the bypass line and a ground point, and the semiconductor element It is detected whether or not a forward current flows through the PN junction, and when the current flows, it is confirmed that either the section of the bypass line on the device side of the ground resistance means or the electric wire is disconnected. To detect And line detecting means, a disconnection detecting device characterized by comprising a are the gist.

According to a second aspect of the present invention, in the disconnection detecting device according to the first aspect, the semiconductor element is a PNP transistor connected in series to the bypass line by an emitter terminal and a base terminal, The gist of a wire breakage detection device is characterized in that the wire breakage detection means detects the wire breakage when a collector current of the PNP transistor flows.

[Operation] In the disconnection detection device according to claim 1 configured as described above, a bypass wire is provided in parallel with an electric wire that supplies a direct current to a device from a predetermined power source, and the bypass wire is provided in the bypass wire. In, a semiconductor element having a PN junction structure is connected in series with a terminal to which a P-type semiconductor is connected as a power source side and a terminal to which an N-type semiconductor is connected as a device side.
Further, ground resistance means for connecting the bypass line and the ground point is provided on the device side of the bypass line with respect to the semiconductor element.

When both the electric wire and the bypass wire are normal, the terminal connected to the P-type semiconductor and the terminal connected to the N-type semiconductor of the semiconductor element connected to the bypass wire are short-circuited by the electric wire and are the same. Because of the potential, no forward current flows through the PN junction of the semiconductor element, and the power supply to the device is
A direct current will be supplied through the electric wire.

Here, when the wire is broken, the short circuit between the terminal of the semiconductor element to which the P-type semiconductor is connected and the terminal to which the N-type semiconductor is connected is released, and a forward current flows through the PN junction of the semiconductor element. . Then, this forward current is supplied to the device. That is, in this case, the direct current is supplied from the power source to the device through the semiconductor element and the bypass line.

On the other hand, when the section of the bypass line closer to the device than the place where the ground resistance means is provided is disconnected, the direct current is still supplied from the power source to the device through the electric wire. However, also in this case, the short circuit between the terminal connected to the P-type semiconductor and the terminal connected to the N-type semiconductor of the semiconductor element connected to the bypass line is released, and the N-type semiconductor of the semiconductor element is connected. Since the connected terminal is connected to the ground point via the ground resistance means, a forward current flows through the PN junction of the semiconductor element.

In any of the above cases, when a forward current flows through the PN junction portion of the semiconductor element, the disconnection detection means disconnects either the section of the bypass line closer to the device than the ground resistance means or the electric wire. To detect.

That is, in the disconnection detection device according to claim 1, when the electric wire is disconnected, a direct current is supplied from the power source to the device via the semiconductor element and the bypass line, and the device is connected to the ground resistance means of the bypass line. When the section on the device side is broken, the direct current is still supplied from the power supply to the device through the electric wire.

Then, whichever of the section or the electric wire on the device side of the bypass line is closer to the device than the ground resistance means, a forward current flows through the PN junction of the semiconductor element connected to the bypass line, and the disconnection detection means A disconnection will be detected.

Here, it is conceivable to use a diode as the semiconductor element connected to the bypass line. However, in this case, the disconnection detecting means must be constructed so as to directly detect the forward current or the forward voltage between the anode terminal and the cathode terminal of the diode.

Therefore, in the disconnection detection device according to claim 2, a PNP transistor is used as a semiconductor element, and the PNP transistor is connected in series to the bypass line with the emitter terminal on the power supply side and the base terminal on the device side. I am trying to do it.

In this case, if either the section of the bypass line on the device side of the ground resistance means or the electric wire is disconnected, PN
Since a forward current, that is, a base current flows from the emitter terminal of the P-type transistor to the base terminal, and a collector current flows, the disconnection detection means is more effective than the ground resistance means of the bypass line when the collector current flows. It is detected that either the side section or the electric wire is broken.

Therefore, according to the disconnection detection device of the second aspect, the PN
Since the disconnection of the electric wire or the bypass line can be detected only by detecting the collector current flowing through the collector terminal of the P-type transistor, the structure of the disconnection detecting means can be simplified.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an electric circuit diagram showing a disconnection detection device and related equipment of an embodiment to which the present invention is applied.

As shown in the drawing, a well-known DC 2-wire type proximity switch SW as a device, which is configured to increase the current flowing when an object approaches, is attached to a part of a mechanical device (not shown), One terminal T1 of SW and the terminals P1 and P2 of the connector C are connected by a power supply side lead wire LA and a power supply side bypass wire La as electric wires, respectively, and the other terminal T2 and the terminals P3 and P4 of the connector C are connected. , A ground side lead wire LB as an electric wire and a ground side bypass wire Lb, respectively.

The disconnection detection device 1 detects disconnection of each of the lines LA, La, LB, and Lb, and a positive electrode side current detection circuit 5 that detects that a current has flown in the power supply side bypass line La,
A current is supplied to the power supply side bypass line La or the ground side bypass line Lb by the negative side current detection circuit 7 that detects that a current has flowed in the ground side bypass line Lb and the positive side current detection circuit 5 or the negative side current detection circuit 7. When the flow is detected, it is determined that any one of the lines LA, La, LB, Lb is broken, and the warning lamp WL in the control panel CNT is turned on, and a drive circuit 9 as a disconnection detecting means, Is configured as a main part.

The power supply side lead wire LA is connected to the photocoupler PC inside the sequencer SEQ for controlling the mechanical device via the terminal P2 of the connector C. The photo coupler PC is turned ON-by increasing or decreasing the current flowing from the DC power supply + B to the proximity switch SW due to the non-operation of the proximity switch SW.
Turns off. The power supply side bypass line La is connected to the positive electrode side current detection circuit 5 at the terminal P1 of the connector C.

On the other hand, the ground side lead wire LB is connected to the ground terminal G in the control panel CNT via the terminal P4 of the connector C, and the ground side bypass wire Lb is the terminal P3 of the connector C and the negative side current detection circuit 7 is connected. It is connected to the.

The positive electrode side current detection circuit 5 is composed of a PNP type transistor Tr1 as a semiconductor element, and has a base terminal connected to one terminal T1 of the proximity switch SW3 by the power supply side bypass line La.
, The emitter terminal is connected to the terminal P2 of the connector C and the photocoupler PC of the sequencer SEQ, and the collector terminal is connected to the bias input terminal T3 of the drive circuit 9. The base terminal of the transistor Tr1 is grounded via a resistor R2 as a ground resistance means.

The negative side current detection circuit 7 is mainly composed of an NPN type transistor Tr2 having a grounded emitter and a PNP type transistor Tr3. The base terminal of the transistor Tr2 is connected to the ground side bypass line Lb and the resistor R1.
Is connected to a terminal P2 of the connector C via a resistor R4, and its collector terminal is connected to a base terminal of a transistor Tr3 via a resistor R4. The collector terminal of the transistor Tr3 is connected to the bias input terminal T3 of the drive circuit 9,
The emitter terminal is directly connected to the emitter terminal of the transistor Tr1 via the resistor R3.

The drive circuit 9 includes a transistor Tr1 or a transistor T1.
It is composed of a constant current circuit CC that outputs a predetermined constant current 1B regardless of the magnitude of the input current when fed from r3, and an NPN type power transistor Tr4. From the constant current circuit CC, a constant current 1B, that is, a bias current. Is supplied,
The power transistor Tr4 is turned on to turn on the alarm lamp WL of the control panel CNT.

Next, the operation of the disconnection detection device 1 will be described.

When the bypass line La on the power supply side is disconnected at the point X1, in the transistor Tr1 of the current detection circuit 5 on the positive electrode side, a forward potential difference occurs between the emitter and the base, and the bias voltage is applied. Therefore, the current 11 is supplied to the power supply side bypass line La on the emitter terminal side of the transistor Tr1, the transistor Tr1,
While flowing to the resistor R2 and the ground terminal G, the transistor Tr1 is turned on and the collector current Ic1 flows. Since this collector current Ic1 is input to the constant current circuit CC of the drive circuit 9, the transistor Tr4 of the drive circuit 9 is turned on to turn on the alarm lamp WL. The operating current 10 is
As it flows to the power source side lead wire LA, the proximity switch SW, and the ground side lead wire LB as it is, the power source side bypass wire La
Even if is disconnected, the proximity switch SW operates normally.

When the lead wire LA on the power supply side is disconnected at the point X2, a forward potential difference occurs between the emitter and base of the transistor Tr1 and a bias voltage is applied to the transistor Tr1. Therefore, the current 12 flows to the power supply side bypass line La on the emitter terminal side of the transistor Tr1, the transistor Tr1, the power supply side bypass line La on the base terminal side of the transistor Tr1, and the proximity switch SW, and the transistor Tr1 is turned on.
Then, the collector current Ic1 flows. Since the collector current Ic1 is input to the constant current circuit CC, the transistor Tr4 is turned on to turn on the alarm lamp WL. In this way, the current 12 flows to the transistor Tr1, the power supply side bypass line La, the proximity switch SW, and the ground side lead wire LB, so that the proximity switch SW operates normally even if the power supply side lead LA is disconnected.

When the ground side bypass line Lb is disconnected at the point X3, in the transistor Tr2 of the negative side current detection circuit 7, a forward potential difference occurs between the base and the emitter, and the bias voltage is applied. Therefore, the current 13 is the resistance R1 and the transistor Tr.
2, while flowing to the ground side bypass line Lb on the emitter terminal side of the transistor Tr2 and the ground terminal G, the transistor Tr2 is turned on. Then, the collector current Ic2 flows to the ground terminal G via the resistor R3. Then, in the transistor Tr3, a forward potential difference occurs between the emitter and the base. That is, a bias voltage is applied to the transistor Tr3 and the transistor Tr3 becomes conductive. Therefore, the collector current Ic3 flows into the constant current circuit CC of the drive circuit 9, and the transistor Tr4 is turned on to turn on the alarm lamp WL. The operating current 10 is the same as the power source side lead L.
Since it flows to A, the proximity switch SW, and the ground side lead wire LB, the proximity switch SW operates normally even if the ground side bypass line Lb is disconnected.

When the ground side lead wire LB is disconnected at the point X4, a forward potential difference is generated between the base and emitter of the transistor Tr2, and the bias voltage is applied to the transistor Tr2. So
The current 14 is the ground side bypass line Lb on the base terminal side of the transistor Tr2, the transistor Tr2, and the transistor Tr2.
While flowing to the ground side bypass line Lb on the emitter side and the ground terminal G, the transistor Tr2 is turned on and the collector current Ic2 flows through the resistor R3. Then, the transistor Tr3 becomes conductive and the collector current Ic3 becomes constant current circuit C.
Flow to C, transistor Tr4 is turned on and alarm lamp WL
Light up. In this way, the current 14 flows to the power supply side lead LA, the proximity switch SW, the ground side lead wire Lb, and the transistor Tr2, so that the proximity switch SW operates normally even if the ground side lead wire LB is disconnected.

Note that the resistance values of the resistors R1 and R2 are set so that a bias current flows through the transistors Tr1 and Tr2 at the time of disconnection, and are sufficiently large, so that when the lines LA, La, LB, and Lb are normal, the resistance values from the resistors R1 and R2 are reduced. The current flowing to the ground terminal G is extremely small.

As described above, in this embodiment, each line LA, La, LB, L
When any one of b is disconnected, the drive circuit 9 turns on the alarm lamp WL. Therefore, the occurrence of disconnection can be immediately known.

Further, when the lead wires LA and LB are disconnected, the transistors Tr1 and Tr2 become conductive and the currents 12 and 14 flow into the bypass lines La and Lb and the proximity switch SW, so that the proximity switch SW can operate normally. on the other hand,
When the bypass lines LB and Lb are disconnected, the operating current 10 is directly applied to the lead lines LA and LB and the proximity switch SW.
, The proximity switch SW can operate as it is.

Next, the disconnection detection device of the second embodiment will be described. In the second embodiment, the lead wire L of the proximity switch SW
The connection of A, LB and the bypass lines La, Lb to the connector C is the same as in the first embodiment. As shown in FIG.
The disconnection detection device 20 is provided on each of the bypass lines La and Lb.
The diodes D1 and D2, which are provided in series in the forward direction, and the differential amplifier circuits 22 and 24 that amplify and output the potential difference across the diodes D1 and D2 are mainly configured.

The cathode terminal of the diode D1 is the terminal P of the connector C.
2 and the photocoupler PC of the sequencer SEQ. The cathode terminal of the diode D1 is grounded via the resistor R30. On the other hand, the diode D2
The anode terminal of is connected to the terminal P3 of the connector C and is also connected to the DC power source + B via the resistor R31, and the cathode terminal thereof is connected to the terminal P4 of the connector C.

The differential amplifier circuits 22 and 24 are well-known operational amplifiers OP1 and OP1, respectively.
OP2 is a main part, and operational amplifiers OP1, O
The difference between the input voltages to the inverting and non-inverting input terminals of P2 is amplified to a predetermined voltage.

The non-inverting input terminal of the differential amplifier circuit 22 is connected to the anode terminal of the diode D1 via the resistor R10, and the inverting input terminal is connected to the cathode terminal of the diode D1 via the resistor R11. Further, the non-inverting input terminal of the differential amplifier circuit 24 is connected to the anode terminal of the diode D2 via the resistor R20, and the inverting input terminal is connected to the resistor R21.
Is connected to the cathode terminal of the diode D2 via. That is, the voltages across the diodes D1 and D2 are
It is input to the differential amplifier circuits 22 and 24.

Forward potential difference VD1, V across the diodes D1, D2
When D2 occurs, the potential difference VD1 and VD2 is
The signals 2 and 24 are amplified to predetermined voltages VDR1 and VDR2 and output to the light emitting diode PD in the control panel CNT. That is, in the disconnection detection device 20, the diode D1 corresponds to the semiconductor element, the resistor R30 corresponds to the ground resistance means, and the differential amplifier circuit 22 corresponds to the disconnection detection means.

Next, the operation of the disconnection detection device 20 will be described.

When the power supply side bypass line La is disconnected at the point X1, a forward potential difference VD1 is generated at both ends of the diode D1 and the diode D1 becomes conductive. Therefore, the forward current IF1 flows through the diode D1, the resistor R30, and the ground terminal G. Then, the potential difference VD1 is amplified to a predetermined voltage VDR1 by the differential amplifier circuit 22 and output to the light emitting diode PD in the control panel CNT. Therefore, the light emitting diode PD is turned on to notify the disconnection. Further, since the operating current 10 flows to the power supply side lead wire LA, the proximity switch SW, and the ground side lead wire LB as it is, the proximity switch SW operates normally even if the power supply side bypass line La is disconnected.

When the lead wire LA on the power supply side is disconnected at the point X2, a potential difference VD1 in the forward direction is generated at both ends of the diode D1 and the diode D1
1 conducts. Therefore, the current IF1 is the diode D
1, the power supply side bypass line La, the proximity switch SW, and the ground side lead wire LB can flow, so that the proximity switch SW operates normally even if the power supply side lead wire LA is disconnected. In addition, the potential difference VD1 is the predetermined voltage V
Light-emitting diode PD in control panel CNT amplified by DR1
Is output to. Therefore, the light emitting diode PD is turned on to notify the disconnection.

When the ground side bypass line Lb is disconnected at the point X3, a forward potential difference VD2 is generated at both ends of the diode D2, and the diode D2 becomes conductive. Therefore, the forward current IF2 is applied to the resistor R3.
1, the diode D2, and the ground terminal G. Then, the potential difference VD2 is amplified to a predetermined voltage VDR2 by the differential amplifier circuit 24 and output to the light emitting diode PD in the control panel CNT. Therefore, the light emitting diode PD is turned on to notify the disconnection. Further, since the operating current 10 flows to the power supply side lead wire LA, the proximity switch SW, and the ground side lead wire LB as it is, the proximity switch SW operates normally even if the ground side bypass line Lb is disconnected.

When the ground side lead wire LB is broken at the point X4, a forward potential difference VD2 is generated at both ends of the diode D2, and the diode D2
2 conducts. Therefore, the current IF2 can flow to the power supply side lead wire LA, the proximity switch SW, the ground side bypass line Lb, the diode D2, and the ground terminal G. Therefore, even if the ground side lead wire LB is disconnected, the proximity switch SW is normal. To work. Further, the potential difference VD2 is amplified to a predetermined voltage VDR2 by the differential amplifier circuit 24 and output to the light emitting diode PD in the control panel CNT. Therefore, the light emitting diode PD is turned on to notify the disconnection.

As described above, the disconnection detection device 20 of the second embodiment also has the same effect as that of the first embodiment.

[Effects of the Invention] As described in detail above, according to the disconnection detection device of the present invention,
If the wire is broken, a DC current can be supplied to the device from the power supply through the semiconductor element and the bypass wire.
If the section of the bypass line on the device side of the ground resistance means is disconnected, the direct current is still supplied from the power source to the device via the electric wire. Then, whichever of the section or the electric wire on the equipment side of the bypass line is closer to the device than the ground resistance means, a forward current flows through the PN junction of the semiconductor element connected to the bypass line, and the disconnection detection means disconnects the wire. Can be detected.

Therefore, according to the disconnection detecting device of the present invention, even if the section of the bypass line on the device side of the grounding resistance means or the wire is disconnected, the DC current is supplied to the device such as the sensor while detecting the disconnection. Therefore, it is possible to repair the disconnection without stopping the operation of the device such as the sensor unlike the conventional device.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing the disconnection detection device and related equipment of the embodiment, and FIG. 2 is an electrical circuit diagram showing the disconnection detection device and related equipment of the second embodiment. 1, 20 ... Disconnection detection device 5 ... Positive side current detection circuit 7 ... Negative side current detection circuit, 9 ... Driving circuit LA ... Power supply side lead wire La ... Power supply side bypass wire LB ... Ground side lead wire Lb ... Ground side bypass wire Tr1, Tr2 ... Transistor 22, 24 ... Differential amplifier circuit D1, D2 ... Diode R1, R2, R30, R31 ... Resistor SW ... Proximity switch

Claims (2)

[Scope of utility model registration request] 1. A disconnection detecting device for detecting disconnection of an electric wire for supplying a direct current to a device from a predetermined power supply, the bypass wire being provided in parallel with the electric wire, and having a PN junction structure, A semiconductor element connected in series to the bypass line with the terminal connected to the P-type semiconductor serving as the power source side and the terminal connected to the N-type semiconductor serving as the device side; Ground resistance means provided on the device side for connecting the bypass line to the ground point, and whether or not a forward current has flown to the PN junction of the semiconductor element is detected. A disconnection detecting device, comprising: a disconnection detecting unit that detects a disconnection of a section of the bypass line closer to the device than the grounding resistance unit or the electric wire. 2. The disconnection detecting device according to claim 1, wherein the semiconductor element is a PNP transistor connected in series to the bypass line by an emitter terminal and a base terminal, and the disconnection detecting means is the above-mentioned. A disconnection detecting device, characterized in that the disconnection is detected when a collector current of a PNP transistor flows.