JP2515936Y2 - Earth leakage detector - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an earth leakage detector used for an earth leakage circuit breaker or the like, and in particular, supplies power from the load side of the earth leakage circuit breaker or the like, The present invention relates to an earth leakage detector for reverse connection.

[Conventional technology]

FIG. 3 is a circuit diagram of the entire earth leakage breaker, and FIG. 4 is a circuit configuration diagram of a conventional earth leakage detector.

Here, if a current imbalance occurs in the main circuits 17 and 17 'of FIG. 3 when the power source is connected to the 19 and 19' side of FIG. A voltage is generated in the resistor 2'on the secondary winding side of the phase current transformer 2, amplified by the amplifier 3, compared with the reference voltage Vs by the comparator 4, and when the voltage exceeds Vs, the first constant current generating circuit 5 is operated. It is driven to charge the first capacitor 6. When the charging time is too long and the charging voltage of the first capacitor 6 exceeds the operating voltage of the latch circuit 7, the latch circuit 7 drives the second constant current generating circuit 10 to charge the second capacitor 11. . The voltage of the second capacitor 11 exceeds the gate turn-on voltage of the thyristor 12, and at that time, it is just the thyristor.
If voltage is applied to the 12 anodes, the thyristor 12
When turned on, a large tripping current flows through the trip coil 16, and the trip coil 16 disconnects the main circuit contacts 18 and 18 'to stop the power supply to the load and the detector 1.

However, the voltage of the anode of the thyristor 12 is 17,17 '.
Since the line voltage is a voltage half-wave rectified by the diode 15, the half-wave component always has a time when no voltage is applied. If the timing at which the charging voltage of the second capacitor 11 is generated is just at the end of a half-wave with a voltage, even if the thyristor 12 is turned on, current does not flow in the trip coil 16 for a sufficient time, The main circuit contacts 18,18 'cannot be tripped, and in order to completely trip 18,18', the voltage applied to the gate of the thyristor 12, that is, the charging voltage of the second capacitor 11 is increased to the next half-wave voltage. Must be retained.
Therefore, in the conventional detector, the driving of the first constant current generating circuit 5 is stopped and the charging of the first capacitor 6 from 5 is stopped, and conversely, the constant current discharging circuit of 5'converses the charging of the first capacitor 6. To prevent the charge from being discharged by the current of I5 ′ and lowering the voltage, the charge voltage of the first capacitor 6 is directed from the latch circuit 7 to the first capacitor 6 so that the operating voltage of the latch circuit 7 can be maintained. Current I7 larger than I5 'is replenished, the charging voltage of the capacitor 6 is held at a constant voltage, and the latch circuit 7 continues to operate. That is, the latch circuit 7 cannot continue its operation without the charging voltage of the first capacitor 6. If the latch circuit 7 continues to operate, the second constant current generating circuit 10 also continues to be driven, and the voltage of the second capacitor 11 continues to be held, so that the thyristor 12 eventually turns ON at a half-wave voltage and the trip coil
Energize the trip current to 16 for a sufficient time, and
8'is designed to be tripped.

When the main circuit contacts 18,18 'are tripped, the main circuit wires 17,1
Since power is not supplied to 19 'from 7', the current flowing through trip coil 16 also disappears and capacitors 6, 11, 13
The charging voltage of the thyristor is discharged and the voltage disappears, and the anode voltage of the thyristor 12 also disappears, so the thyristor 12 is turned off, and when the main circuit contacts 18 and 18 'are closed again, the detector as a whole is reset. The tripping coil 16 does not trip until an unbalanced current flows through the main circuit contacts 17 and 17 '.

[Problems of conventional technology]

However, in the above-mentioned conventional detector, the operation is slightly different when the power source is connected to the terminals 20 and 20 '. That is, after detecting the unbalanced current of the main circuit contacts 17 and 17 'and tripping the main circuit contacts 18 and 18', the entire detector does not reset, and the trip current continues to flow to the trip coil 16. A problem arises.

 The state will be described below.

The operation up to detecting the unbalanced current in the main circuit wires 17 and 17 'and disconnecting the main circuit contacts 18 and 18' is the same as when the power source is connected to the terminals 19 and 19 ', so the description is omitted. .

FIG. 5 shows the terminals of FIG. 3 in the conventional circuit of FIG.
Anode-cathode voltage VSR of thyristor 12 before and after leakage detection operation at time t2 when power supply voltage is applied to 20, 20 'side
(B), the voltage VC13 across the voltage smoothing capacitor 13
FIG. 7E is a diagram showing a state of the voltage VC11 (d) across the second capacitor 11. Before the time t2 when the detector circuit 8 detects the leakage and the thyristor 12 turns ON,
Since 12 is turned off, VSR is almost the same waveform as the half-wave rectified AC voltage waveform of the power supply indicated by the dotted line, and VC13 is
The waveform of VSR voltage dropped by the resistor 14 and charged in the smoothing capacitor 13 has a pulsating flow. The second capacitor 11
There is no output voltage generated at. When the detector circuit 8 generates the output voltage VC11 (d) at t2, the voltage of the thyristor 12 is half-wave rectified by the diode 15, and the voltage of the anode of the thyristor 12 is immediately turned on. Drops to a drop voltage va between the anode and the cathode when the thyristor 12 is turned on, which is about 1.2V. The thyristor 12 is turned on and the tripping current flows through the tripping coil 16, but the timing is near the end of the half-wave voltage. Therefore, the main circuit contacts 18 and 18 'are actually tripped after about one cycle. We will wait until t4 near the end of the wave. At t3, the voltage is no longer supplied from the diode 15 side, and the anode potential VSR should be 0 V, but this time at t2, the smoothing capacitor 13 charged before the trip trigger signal VC11 is generated.
Voltage is supplied from the resistor 14 via
R does not become 0V and va will be maintained. On the other hand, the voltage VC13 across the smoothing capacitor 13 is the diode 15 before t2.
Is charged by being supplied with a half-wave rectified voltage from the diode, and then the charged charge is supplied from the diode 15 to the detector circuit 8 during a half-wave when no voltage is supplied, and charging and discharging are performed while maintaining the minimum voltage vH. It becomes a pulsating flow by repeating. When the thyristor 12 is turned on at time t2, VSR drops to va. Therefore, the smoothing capacitor 13 must supply current to the detector circuit 8 and also to the thyristor 12 through the resistor 14. However, the minimum voltage vH before that cannot be maintained and the voltage drops rapidly.
Since the anode potential VSR of the above does not fall below va, the voltage VC13 across the smoothing capacitor 13 also does not fall below va. However, the operation of the detector circuit 8 can be active until va becomes about 0.5 V, and is unstable even in the actual va = about 1.2 V, but the latch circuit 7 and the second constant current generating circuit Ten
Operable near the edge, and therefore a second capacitor
The detector circuit output VC11 continues to be generated at both ends of 11, and the trigger of the thyristor 12 is not released.Each time the half-wave voltage rectified by the diode 15 comes, the thyristor's anode and cathode operate ON, Each time the trip current continues to flow through the trip coil 16, the main circuit contacts 18, 18 '
Not only cannot be input again, but the trip coil 16 will be burned out.

[Purpose of device]

Even if power is connected to terminals 20 and 20 ', main circuit contact 18,
After tripping 18 ', the detector circuit 8 and thyristor 12 return to the reset state, the main circuit contacts 18, 18' can be reclosed after tripping, and the trip coil 16 does not burn out. I will provide a.

[Means for achieving the purpose]

In view of the above object, the invention of the present invention is based on the conventional leakage detector of FIG. 4, in which the first capacitor 6 is charged by detecting the leakage, the charging voltage reaches the operating voltage of the latch circuit 7, and the rear latch circuit 7 operates. The point where the charging voltage of the first capacitor 6 is held at a constant voltage, and the operation of the detector 8 when the potential of the capacitor 13 after the turn-on of the thyristor 12 drops to near the anode / cathode potential va when the thyristor 12 is on. Is unstable, but the charging voltage of the first capacitor 6 is held at a constant voltage due to a very delicate current relationship, and the second capacitor is held.
Focusing on the fact that the gate trigger voltage of the thyristor 12 is continuously output to 11, the charging voltage of the capacitor 13 drops to near va described above, and the charging voltage of the first capacitor 6 is held at a constant voltage. In order to maintain the operating voltage of the latch circuit 7 at the charging voltage end of the first capacitor 6, the charging / discharging operation of the first capacitor 6 of the latch circuit 7 becomes very slow and slow. Is added to the latch circuit 7, which requires a very agile and frequent charge / discharge operation. When the charging voltage of the capacitor 13 drops to near va, the operating voltage of the latch circuit 7 is changed. The charge / discharge of the first capacitor 6 for maintaining is prevented from catching up so that the potential at the voltage end of the first capacitor 6 cannot be maintained at the operating voltage of the latch circuit 7, and as a result, the thyristor 12 has Trigger Total release to the detector a is one configured to reset.

Therefore, in the present invention, a voltage generating means for causing a voltage undulation due to the half-wave current flowing in the trip coil is inserted between the first capacitor 6 and the ground line in FIG.
The latch circuit 7 is forcibly and frequently required to be charged and discharged due to the voltage fluctuation.

[Detailed description of the invention]

 Embodiments will be described below with reference to the drawings.

FIG. 1 is a first embodiment of the present invention, in which the ground line side of the capacitor 6 of FIG. 1 is connected to the gate of the thyristor 12. Here, the capacitors 6 and 11 are set to have a capacitance several times larger than that of the capacitor 11.

The operation of the embodiment connected as described above will be described with reference to the time chart of FIG.

In FIG. 2, i is the leakage current flowing on the primary side of the zero-phase current transformer 2, and is assumed to have occurred at time t1. The secondary output voltage of the zero-phase current transformer is amplified by the amplifier 3, compared with the reference voltage Vs by the comparator 4, and starts driving the constant current generator 5 at t2. Start charging the series circuit of capacitor 11 as Vc6 + Vc11. Vc6 at time t3
+ Vc11 reaches the operating voltage VR of the latch circuit 7, the latch circuit 7 is driven, the constant current generating circuit 10 charges the capacitor 11 and raises Vc11 by the voltage of VtG, and the latch circuit 7 becomes Vc6 + Vc11 in FIG. To hold the operation of the latch circuit 7 itself as a constant voltage. Immediately before Vc6 + Vc11 reaches VR, the charging voltage Vc11 of the second capacitor 11
As described above, the second capacitor 11 has a much larger capacitance than the first capacitor 6, so
It is much lower than the charging voltage Vc6 of the first capacitor 6 and does not trigger the gate of the thyristor 12.

At time t3, the charging voltage of the capacitor 11 is the constant current generation circuit.
The output of 10 instantly raises the voltage just before t3 by VtG to a voltage sufficient to trigger the gate of thyristor 12. Since Vc6 + Vc11 is held in VR by the latch circuit 7 as a constant voltage, Vc6 rises by VtG and Vc6 is Vt on the contrary.
G needs to fall. This is because the latch circuit 7 changes Vc6 to VtG.
This is accomplished by reducing I7 in Figure 1 as much as is necessary to reduce it. In some cases, I7 absorbs a current from the capacitor 6, that is, becomes a current in the direction opposite to the arrow in FIG. When the thyristor 12 is triggered at time t3, the half-wave voltage rectified by the diode 15 is applied to the anode of the thyristor 12 at that time,
Immediately, the thyristor 12 is turned on and the anode-cathode voltage VSR of the thyristor 12 drops to the anode-cathode voltage va when it is on. Although the thyristor 12 is turned on as described above, the timing of turning on is just before the end of the half-wave voltage, and the trip current does not flow in the trip coil 16 for a sufficient time, so that the main circuit contacts 18 and 18 'are not tripped. At time t4, the power supply voltage is reversed in polarity opposite to that of the diode 15, and the supply of current from the diode 15 side to the thyristor 12 is stopped. However, the current is supplied through the resistor 14 from the fully charged capacitor 13 before the time t3, the thyristor 12 maintains the ON state, and the capacitor 13 supplies the current to the detection circuit 8 and the thyristor 12, so that the voltage rapidly decreases. However, there is a margin until the operation of the leakage detection circuit 8 becomes unstable, and Vc6 + Vc11 and Vc11
Is also stable. The trip current flows through the thyristor 12 again from time t5, but this time the current flows from the beginning of the half-wave rectified voltage, so that the trip coil 16 is energized for a sufficient time and at time t6 the main circuit contact 18 , 18 'is tripped,
The leakage current i on the primary side of the zero-phase current transformer 2 is interrupted. On the other hand, since a half-wave alternating current from t5 to t7 flows from the anode to the cathode of the thyristor 12, a potential rise proportional to the anode-cathode current is generated between the gate and the cathode according to the impedance between them and Vc11 in the figure. It appears as between t5 and t7 of the above, and the potential increase is the first capacitor 6
The voltage Vc6 between both ends of T is reduced from t5 to t7, and it works again. At this time, the latch circuit 7 needs to decrease I7 on the curved surface where Vc6 decreases, or conversely absorb the electric charge of the capacitor 6, and increase I7 on the curved surface where Vc6 rises to the original voltage. In other words, the latch circuit 7 is required to quickly charge and discharge by following the change of Vc11, but even at the time of t7, Vc13 is a voltage against which the operation of the leakage detection circuit 8 becomes unstable. There is a margin, and the charge / discharge of the first capacitor 6 of the latch circuit 7 can sufficiently follow the change of the charging voltage of the second capacitor 11 and Vc6 + Vc11 can be held at a constant voltage.

However, during the same half-wave voltage rectified by the diode 15, i.e. between t8 and t9, during the same operation described above, Vc
13 is fully discharged and the anode of thyristor 12 when on
Since the voltage between the cathodes is lowered to near va and the operation of the latch circuit 7 is also slowed down, when VC6 from t8 to t9 is once lowered and it is tried to return to the original voltage again, finally the latch circuit 7
, The charging current I7 from the first capacitor 6 cannot follow,
Since Vc6 cannot return to the original voltage, the voltage of Vc6 + Vc11 cannot hold the voltage VR necessary for maintaining the operation of the latch circuit 7, and the constant current generation circuit 10 by the latch circuit 7 can be held.
Is also stopped, the voltage across the capacitor 11 drops, the thyristor 12 trigger is released, and the capacitor
Since the voltage of 13 has dropped to almost Va, the thyristor 12
The current between the anode and the cathode does not flow, and when the polarity of the power supply voltage is inverted with respect to the diode 15 after t9, the thyristor 12 is turned off and the entire detector can be reset.

FIG. 6 shows a second embodiment of the present invention. In the second embodiment, a low resistance 21 of about 1Ω is inserted between the cathode of the thyristor 12 and the earth line, and the trip current of the trip coil 16 causes A voltage of about 1 V is generated across the resistor 21 only when a half-wave current flows through the trip coil, and the ground line side of the first capacitor 6 is connected to the connection point between the cathode of the thyristor 12 and the resistor 21. However, the operating principle is almost the same as that of the first embodiment shown in FIG. FIG. 7 is a modification of the first embodiment of FIG. 1, in which a diode 22 and a resistor 23 are added to make the charging of the first capacitor 6 an integral type.
The reset principle operation is the same as that of the first embodiment of FIG. The same modification can be made in the second embodiment shown in FIG.

In FIG. 1, it should be noted that the same operation is performed without the second capacitor 11. The capacitor 11 is inserted for more stable gate triggering of the thyristor 12, and the present invention does not depend on the presence of the capacitor 11.

[Action and effect]

As described above, in the present invention, the secondary output voltage of the zero-phase current transformer is compared with the reference value, and when the reference value is exceeded, the first capacitor is charged, and the charging voltage of the first capacitor is a certain value. Leakage detection such as having a latch circuit for generating an output signal when the voltage reaches a predetermined value, and thereafter holding the voltage between the charging voltage end of the first capacitor and the earth line at the constant value as a constant voltage and continuing to hold the output signal. Circuit, a thyristor that is turned on by using the output signal of the earth leakage detection circuit as a trigger, and a half-wave rectified voltage is supplied to the anode of the thyristor via a trip coil, and the anode of the thyristor is supplied via a voltage drop resistor. In a leakage detector in which a power supply voltage is supplied to a ripple smoothing capacitor and the leakage detection circuit, an anode of a thyristor is provided between the first capacitor and a ground line. Since a voltage generating means having undulations corresponding to the trip current flowing between the swords is inserted, even if the power supply is reversely connected, the trip current is detected between the thyristor's anode and cathode after the leakage is detected and the thyristor turns on. Each time it flows, the latch circuit must quickly charge and discharge the first capacitor so that the voltage between the voltage end of the first capacitor and the ground line must be maintained at a constant voltage.
After the thyristor turns on, the charging voltage of the smoothing capacitor drops to such a low voltage that the operation of the leakage detection circuit becomes unstable, and when the charging and discharging of the first capacitor of the latch circuit becomes slow, The voltage between the capacitor of 1 and the earth line cannot be maintained at the operating voltage of the latch circuit,
The operation of the latch circuit is stopped, the detector circuit is reset, the trigger of the thyristor is also released, and the thyristor is also reset, so it is possible to re-close after the main circuit contacts 18 and 18 'are tripped,
Moreover, there is an effect that it is possible to obtain a leakage detector that does not burn the trip coil 16.

Further, as the voltage generating means, when a tripping current flows between the anode and cathode of the thyristor, an impedance component between the gate and cathode of the thyristor that generates current according to the tripping current is used, and the ground of the first capacitor is used. The end on the line side is connected to the gate of the thyristor, or a resistor is connected between the cathode of the thyristor and the earth line to be used as a voltage generating means. The end of the first capacitor on the earth line side is connected to the cathode of the thyristor. Since it is connected to the connection end of the resistor, it has an effect that it can be constructed very easily.

[Brief description of drawings]

Fig. 1 ... Circuit configuration diagram of the leakage detector according to the first embodiment of the present invention, Fig. 2 ... Operation time chart of the leakage detector of Fig. 1, Fig. 3 ... Circuit of entire leakage breaker Configuration diagram, FIG. 4 ... Circuit configuration diagram of conventional leakage detector, FIG. 5 ... Operation time chart of conventional leakage detector, FIG. 6 ... Leakage detector according to second embodiment of the present invention Circuit configuration diagram of Fig. 7 ... Example of application circuit of the present invention. 2 ... Zero-phase current transformer, 4 ... Comparator, 6 ... First capacitor, 7 ... Latch circuit, 12 ... Thyristor, 13 ... Ripple smoothing capacitor, 14 ... Voltage drop resistance, 15
...... Diode for half-wave rectification, 16 ...... Tripping coil, 21 ...
…resistance.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masaharu Aoki 3-42 Dashu, Minami-ku, Hiroshima City, Hiroshima Prefecture Temporary Industrial Co., Ltd. (72) (72) Tetsuo Furumoto 3-chome, Oshu, Minami-ku, Hiroshima City, Hiroshima Prefecture 1-42 Examiner at Tempar Industries Co., Ltd. Shinichi Yajima (56) References JP 54-136668 (JP, A)

Claims (3)

(57) [Scope of utility model registration request] 1. A comparison circuit for amplifying a secondary output voltage of a zero-phase current transformer and comparing it with a reference value, a first capacitor charged by the output of the comparison circuit, and a charging voltage end of the first capacitor. When the voltage between the ground lines reaches a certain value, an output signal is generated, and thereafter, the voltage between the charging voltage end of the first capacitor and the ground line is held at the above constant value as a constant voltage and the output signal is continuously held. An earth leakage detection circuit having a latch circuit, a thyristor that is turned on by using an output signal of the earth leakage detection circuit as a trigger, and a half-wave rectified voltage is supplied to the anode of the thyristor through a trip coil, and from the anode of the thyristor. In a leakage detector in which a power supply voltage is supplied to a ripple smoothing capacitor and the leakage detection circuit via a voltage drop resistor, between the first capacitor and a ground line. Leak detector, characterized in that the insertion of the voltage generating means for generating a relief of the anode and the tripping flowing between the cathode voltage corresponding to the current of the thyristor. 2. The voltage generating means is impedance of a gate and a cathode of the thyristor, and an end portion of the first capacitor on a ground line side is connected to a gate of the thyristor. The leak detector according to claim (1) of the utility model registration claim. 3. The voltage generating means is a resistor connected between the cathode of the thyristor and an earth line, and the end portion of the first capacitor on the earth line side is at a connection point between the cathode of the thyristor and the resistor. The leakage detector according to claim (1), characterized in that it is connected.