JPS5940270A - Current detecting apparatus - Google Patents

Abstract

PURPOSE:To coincide time constants at the times of charging and discharging without especially providing reference voltage, by a method wherein a duty detecting circuit is driven by totem pole output and other resistance different from resistor for detecting duty and a capacitor are provided. CONSTITUTION:A capacitor 86 performs charging and discharging through a resistor 85 corresponding to the electrical connection and the cut-off of the transistor 47 of a magnetic multiplex circuit 4 even in a duty detecting circuit 6 similarity to a duty detecting circuit 5. Because a resistor 72 and a capacitor 73 are driven by totem pole output corresponding to the duty from the circuit 4 and charging and discharging time constants are equal, the charging voltage of the capacitor 73 moves up and down on the basis of 0V being the intermediate value between DC voltages +Vcc and -Vcc. In addition, a resistor 85 and a capacitor 86 are driven by totem pole output corresponding to the duty from the circuit 4 and the charging voltage of the condenser 86 moves up and down on the basis of 0V similarily as mentioned above. Therefore, the reference voltages of the outputs from the circuits are coincided and mutual adjustment between the circuits 5, 6 is not necessitated without especially providing reference voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current detection device, and more specifically, the present invention relates to a current detection device, and more specifically, it is provided in connection with a line through which a current to be detected flows, and has secondary and tertiary current detection devices for detecting the current to be detected. A magnetic multi-by break circuit is constructed by a saturable reactor having a secondary coil, a resistor for detecting the current flowing through the secondary and tertiary coils, and a multi-by break circuit that oscillates by changing the duty of a predetermined period according to the detected current. A pair of duty detection circuits are provided for detecting the respective duties, and the level of the difference between the outputs corresponding to the duty from each duty detection circuit is discriminated, and when the discrimination level is exceeded, the response circuit is operated. The present invention relates to a current detection device configured as described above.

Referring to FIG. 1, in the duty detection circuits A and B in the prior art, in order to detect the duty, the reference voltage E1 is set by the resistors R3 and R4, and the resistor 1'<7, R
The reference voltages E2 and E2 of the duty detection circuits A and B were required to be mutually adjusted. Also, diode-1'D1. If I')2 is not available, the time constant during charging is (R1+R2)・C1, (R
4+R5)・C2, and the time constant during discharge is R1・C1,
R5·C2, and the time constants during charging and discharging are different. Also, the diode D1. Even if there is D2,
The time constants during charging are R2·C1, R6·C2, and the time constants during discharging are R1·CI, R,5·C2, and the time constants during charging and discharging are different. Therefore the resistance R
If the resistance value between R1 and R2 and the resistance value between resistors R5 and R6 vary, a problem arises in that the duty cannot be detected accurately.

An object of the present invention is to solve the technical problems mentioned above, and to provide a current detection device equipped with a duty detection circuit that has the same time constant during charging and discharging without providing a special reference voltage. It is to be.

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 2 is a circuit diagram of one embodiment of the present invention. AC power supply 191]
AC power from is provided to load 198 via active line 31 and neutral line 32, respectively. In addition, the AC power supply 199 and the load 198 are connected to the protective ground line 2.
Connected by 00. Current 11 flowing in line 31
and the mutual difference (il~
i2) The direct and alternating currents to be detected (for example) the hanging cage are detected by the current detection device 1.

The current detection device 1 includes a power supply circuit 2, a start circuit 3, a magnetic multivibrator circuit 4, and duty detection circuits 5 and 6.
, a differential amplifier circuit 7, a level discrimination circuit 8, a response circuit 9, and a voltage detection circuit 10.

The power supply circuit 2 has terminals L, N, PR1 resistor 21
, 22, capacitor 23.2/I, and diode 2
5 to 30. Line 3] is terminal, resistor 21,
It is connected to line 33 via capacitor 23 and diode 25 in the forward direction. - The anode of diode 25 is connected to line 34 via diode 26 in the opposite direction. Line 32 is terminal N
and forward connected to line 33 via diode 27. The anode of diode 27 is diode 2
8 in the opposite direction to line 34. The grounding is
Terminal PE is connected to line 33 via resistor 22 and two diodes in the forward direction. The anodes of the two diodes are connected to line 34 via diode 3o in opposite directions. A capacitor 24 is connected between line 33 and line 34 . The AC power via lines 31, 32 is converted into DC power by the power supply circuit 2. This DC power is applied to the start circuit 3 via lines 33,34.

The start circuit 3 includes a transistor 35 as a switching element, a resistor 36, and a Zener diode 37.38.
A 6° line 33 having a 6.degree. The base of transistor 35 is connected to line 3 through Zener diodes 37 and 38 in the opposite direction, respectively.
Connected to 4. The cathode of Zener diode 38 is
Grounded. The cathode of transistor 35 is connected to line 3
Connected to 9.

The constant positive DC voltage 1\'QC from the three lines and the constant negative DC voltage -V cC from the line 34 are the magnetic multivibrate circuit 4 and the duty detection circuits 5 and 6.
, the differential amplifier circuit 7, the level discrimination circuit 8, the response circuit 9, and the voltage detection circuit 10, respectively.

The magnetic multivibrator circuit 1 includes a resistor 4°, a saturable reactor 11, and a multivibrator circuit 42. The saturable reactor 41 includes a core 43 and a pair of secondary windings 44 and tertiary windings 45 having approximately equal numbers of turns n. The multivibrator circuit 42 includes transistors 4.6 and 4.7 as a pair of switching elements.
, Zener diode 48, constant current sources 49, 50, diodes 51 to 58, and resistors 59, 6 (+). Diodes 53, 5 and 1 as negative directional elements form a pair. Also, as unidirectional elements diode 55.5
6 forms a pair.

A DC voltage element \7cc is applied to one end of the resistor 4.0. The other end of the resistor 40 is connected to a secondary and tertiary filter 44.
, 45, respectively. Secondary coil 1
The other end of 14 is connected to connection point 61 . The other end of the tertiary coil 15 is connected to a connection point 62. Connection point 6
A transistor 46 is connected between the 1 and M current voltages -V2C. A diode 51 having a reverse direction is connected in parallel to the transistor 46 . Transistor 17 is connected between connection point 62 and DC voltage -V2C. A diode 52 having a reverse direction is connected in parallel to the transistor 47 .

The DC voltage element cc is connected to the base of the transistor /I6 and the connection point 62 via a constant current source 49 and forward diodes 53 and 54, respectively. The base of the transistor 46 is connected to the DC voltage −\I through a resistor 59.
Connected to C and C. It is connected to the base of transistor 47 and connection point 61 via direct diodes 55 and 56, respectively. The base of transistor 47 is connected to DC voltage -\'cc via resistor 60. DC voltage element
cc also connects to the connection point 61.62 via the forward Zener diode 48 and the reverse diode 57.58.
are connected to each. The output from the connection point 61 is sent to the duty detection circuit 5. The output from the connection point 62 is given to the duty detection circuit 6.

The duty detection circuit 5 includes a constant current source 63, transistors 64, 65, 66, diodes 67, 68, resistors 69 to 72, and a capacitor 73. A series circuit consisting of a constant current source 63 and a resistor 69, a resistor 70, and a transistor 1 are connected between the DC voltage element V6 C+ and \'cc.
1 and a resistor 71, and a series circuit consisting of a diode 67 and a transistor 66 in the direction of the transistor 5.111M are connected, respectively. The connection point between the constant current source 63 and the six resistors is connected to the base of the transistor 64, and is also connected to the connection point 61 through a diode 68 in the forward direction. The collector of the transistor 64 is connected to the base of the transistor 5 ). The emitter of transistor 64 is connected to the base of transistor 66. Transistor 66 includes a resistor 72 and a capacitor 72 driven by the totem pole output.
:(Series circuits consisting of are connected in parallel.

A connection point 74 between resistor 72 and capacitor 73 is connected to a non-inverting input of operational amplifier 75. operational amplifier 75
The inverting input of is connected to the output of operational amplifier 75. Operational amplifier 75 functions as a buffer. The output of the operational amplifier 75 is given to the differential amplifier circuit 7.

The duty detection circuit 6 includes a constant current source 76, transistors 77 to 79, diodes 80 and 81, and resistors 82 to 85.
and a capacitor 86, and is configured similarly to the duty detection circuit 5. The anode of diode 80 is connected to node 62. Resistor 85 and capacitor 86 are driven with totem pole outputs. A connection point 337 between the resistor 85 and the capacitor 86 is connected to the operational amplifier 8 which functions as a buffer.
Connected to the non-inverting input of E; The output of the operational amplifier 88 is given to the differential amplifier circuit 7.

The differential amplifier circuit 7 includes eight operational amplifiers and resistors 90 to 9.
It has 3. The output from the operational amplifier 75 is applied via a resistor 90 to the inverting inputs of eight operational amplifiers. The output from the operational amplifier 88 is connected to the operational amplifier 8 via a resistor 91.
9 non-inverting input. The inverting inputs of the eight operational amplifiers are connected to the output of operational amplifier 89 via resistor 92 . The non-inverting inputs of the eight operational amplifiers are grounded via a resistor 93. The output from the differential amplifier circuit 7 is sent to a level discrimination circuit 8.

Level discrimination circuit 8 has a full-wave rectifier circuit 94 and a time delay circuit 96. The aftermath rectifier circuit 94 integrates the output from the differential amplifier circuit 7 and includes a half-wave voltage doubler rectifier circuit 1()1 and an adder circuit 102.

The half-wave voltage doubler rectifier circuit 101 includes an operational amplifier 103, a diode 104 . , 105 and resistance 1 () 6 to 109
has. The output from the differential amplifier circuit 7 is applied to the inverting input of the operational amplifier 103 via a resistor 106. The inverting input of the operational amplifier 103 is connected to the output of the operational amplifier 1()3 via a resistor 107 and a forward diode 104. The output of operational amplifier 1.03 is connected to operational amplifier 1 through forward diode 105 and resistor 108.
Connected to the inverting input of 03. The non-inverting input of operational amplifier 1()3 is grounded via resistor 109. resistance 10
The grounding point 110 between 7 and the diode 1°4 is connected to the adder circuit 1.
Connected to the input of 02.

The addition circuit 102 includes an operational amplifier 111 and a resistor 112.
~115. The output from the differential amplifier circuit 7 is applied to the non-inverting input of the operational amplifier circuit 111 via a resistor 112. Connection point 110, that is, half-wave voltage doubler rectifier circuit 10
The output from 1 is sent to the operational amplifier circuit 11 via a resistor 113.
1 non-inverting input. A non-inverting input of the operational amplifier circuit 111 is connected to the output of the operational amplifier 111 via a resistor 11.1. The inverting input of operational amplifier 111 is grounded via resistor 115. The output of the operational amplifier 111, that is, the output of the full-wave rectifier circuit 94, is given to a delay circuit 96.

The time delay circuit 96 includes the voltage-current conversion circuit 95, a capacitor 120 for charging a current corresponding to the leakage current, and a period of time until the current charged in the capacitor 120 is discharged to a certain extent and the response circuit 9 is activated. and an operational amplifier 126, a diode 128, a Zener diode 129, and a transistor 130 for level discrimination at a first discrimination level and a second discrimination level less than the first discrimination level.

Voltage-current conversion circuit 95 includes an operational amplifier 116, a transistor 117, a diode 118, and a resistor 119. The 11- output from the full-wave rectifier circuit 94 is applied to the non-inverting input of the operational amplifier 116.

The inverting input of the operational amplifier 116 is grounded through a resistor 119 and connected to the output of the operational amplifier 116 through a diode 118 in the opposite direction. Operational amplifier 11
The emitter of the transistor 117 is connected to the inverting input of the transistor 6. The output of operational amplifier 116 is connected to transistor 1
Connected to 17 beams. Operational amplifier 116 derives its output such that the voltage at its inverting input is equal to the voltage at its non-inverting input.

A capacitor 120 is connected to the collector of the transistor 117, that is, the output of the voltage-current conversion circuit 95 and the DC voltage -Vcc. A current mirror circuit is connected in parallel to the capacitor 120.

The current mirror circuit 97 includes transistors 121.12
2 and a resistor 123. A transistor 121 is connected in parallel to the capacitor 120 . A 12-Tfi column circuit consisting of a resistor 123 and a transistor 122 is connected to ground and to the DC voltage -Vcc. The collector of transistor 122 is connected to the base of transistors 121 and 122, respectively.

The collector of transistor 117 is connected to the non-inverting input of operational amplifier 126. The inverting input of the operational amplifier 126 is connected to ground through a resistor 127 and connected to a forward diode 128 and a reverse Zener diode 12.
9 to the DC voltage -Vcc. A transistor 130 is connected in parallel to the Zener diode 129. The output of operational amplifier 126 is applied to the base of transistor 130 via resistor 131. A transistor 191 is connected to the transistor 122 and the DC voltage -Vcc. The outputs of the operational amplifiers 12 and 6 are applied to the base of a transistor 191 via a resistor 190. The output of operational amplifier 126 is also connected to diode 13
2 in the forward direction to the response circuit 9.

The response circuit 9 includes a trip relay 134 and a transistor 1.
35 and resistors 136 and 437.

Trip relay 134 includes relay fill 138 and relay switch 139, i4. r).

The relay switches 139 and 14.0 of the trip relay are artificially made conductive to the outside when AC power from the AC power supply 199 is applied to the power supply circuit 21. When the relay coil 138 is excited, the relay switches 1, 39, 14 (l
is blocked. DC voltage element \icc.

A relay coil 138 and a transistor 135 are connected in series to -\/ c c ill. The base of transistor 135 is connected directly to the base of transistor 135 via resistor 136.
Connected to N pressure -cc. A resistor 137 and diodes 1, 32, 14 are connected to the base of the transistor 135.
．． 1 to a level discrimination circuit 8 and a voltage detection circuit 10.
The output from is given.

The voltage detection circuit 10 includes a resistor 152 having a high resistance value, a voltage amplification circuit 150, a full-wave rectification circuit 155, and a time delay circuit 149. The voltage amplification circuit 150 includes an operational amplifier 1
51 and resistors 153 and 154. Operational amplifier 15
The inverting input of 1 is connected to terminal PE via resistor 152. Further, the inverting input of the operational amplifier 151 is connected to the resistor 15.
3 to the output of the operational amplifier 151. A non-inverting input of operational amplifier 151 is grounded via resistor 154 . The output of the operational amplifier 151, ie, the output of the voltage amplification circuit 150, is given to a full-wave rectification circuit 155.

The full-wave rectifier circuit 155 includes a half-wave voltage doubler rectifier circuit 156,
It consists of an adder circuit 157. Half-wave voltage doubler rectifier circuit 156
are operational amplifier 158, diode] 59, 16
+'1 and resistors 161 to 164, and is configured similarly to the half-wave voltage doubler rectifier circuit 101. Adder circuit 157 includes an operational amplifier 165 and resistors 166 to 169,
It is configured similarly to the adder circuit 102. The half-wave voltage doubler rectifier circuit 156 and the adder circuit 157 form the full-wave rectifier circuit 1.
55 is formed. The output of the operational amplifier 165, ie, the output of the full-wave rectifier circuit 155, is given to the delay circuit 149.

The time delay circuit 149 includes operational amplifiers 1.70, 176, 1
5- Transistor 1 '71. , 177, diode 17
2°178, resistors 173, 175, 180, 181, Zener diode 179 and capacitor 174,
It is constructed almost similarly to the time delay circuit 96. That is, the resistor 175 is used in place of the Karen mirror circuit 97 of the delay circuit 96. The output of the operational amplifier 176, that is, the output of the time delay circuit 149, is applied to the response circuit 9 via the diode 141 in the forward direction.

AC power supply 199 and terminal, line 31.32 between N
Relay switches 139 and 140 are respectively connected in the middle. Line 3 between terminals, N and load 198
1.32 is provided near the inside or outside of the fan 43 of the saturable reactor 41, respectively.

When AC power is applied via lines 31, 32, the power supply circuit 2 converts this AC power into DC power. When AC power is turned on, the transistor 35 of the start circuit 2 is cut off. Therefore, it is the DC power output side of the power supply circuit 2, that is, the inbegun connected between the lines 33 and 34. Since this impedance is large, line 3
3. The voltage between 34 and 34 suddenly increases. The voltage between line 33 and ground is connected to Zener diode 3 of starting circuit 3.
Above a Zener voltage of 7, transistor 35 becomes conductive.

The conduction of the transistor 35 reduces the impedance. Therefore, the magnetic multivibrator circuit 4,
DC power is rapidly supplied to the duty detection circuit 5.6, the differential amplifier circuit 7, the level discrimination circuit 8, the response circuit 9, the voltage detection circuit 1(), etc., and the current detection device 1 operates smoothly. .

Assume that when relay switches 139 and 140 are artificially made conductive, no leakage occurs in load 198 and there is no abnormality in AC power supply 199. In this case, the current detected by the saturable reactor 41 is zero, and the responsive circuit 96
149 to the response circuit 9 are each at a low level. This low level signal causes transistor 135 to shut off and relay coil 138 to remain demagnetized. Therefore relay switch 139
, 14.0 remain conductive, and the response circuit 9 does not operate.

In the magnetic multivibrator circuit 4, the secondary and tertiary
Next coil 4.4. , 4.5, the coil applied voltage applied to the secondary and tertiary filters 44, 4.5 is Ec, and the saturation magnetic flux of the saturable reactor 41 is φm, the magnetic multivibrator circuit 4 is as follows: It constantly oscillates with a constant period T shown by equation (1).

T=4·n·φm/Ec (1) The transistors 46 and 47 of the multi-bye break circuit 42 are alternately conductive within this period T.

Transistor 47 is cut off. transistor 4 on the road
6 is cut off, transistor 47 is conducting. If the currents flowing in the lines 31.32 are balanced, the voltage induced in the secondary and tertiary filters 4.4, 45 by the lines 31.32 is zero. Therefore, the conduction/cutoff duty ratio of the transistors 46+47 is 50%.

When the F-run raster 46 is conductive and the Y-runge Kuyu 47 is cut off, the current from the resistor 4 () flows through the tertiary coil 45.
does not flow to the transistor 47 via the secondary filter 4.
4 to the transistor 4G. At this point, since the base voltage of the transistor 16 is low, the constant current source 50
The constant current 11 flows through the diode 56 to the transistor 46 and stops flowing through the diode 55 to the transistor 47.

Further, the constant current ■1 from the constant current source 49 is connected to the diode 5.
does not flow to the transistor 47 via the diode 5.
3 to transistor 46. Transistor・
When the base voltage of the transistor 16 becomes high and the base voltage of the transistor 4G is i b and the current amplification factor is h f e, the collector-emitter current becomes 1]·t+ f e, and the transistor 46 enters the active region.

19- When the base voltage of the transistor 46 increases, the constant current 11 from the constant current source 50 no longer flows to the transistor 46 via the diode 5G, but instead flows to the transistor 47I via the diode 55, and the transistor 47 becomes conductive. do. Further, the constant current (1) from the constant current source 49 no longer flows to the transistor 46 via the diode 53, the transistor 46 is cut off, and flows to the transistor 47 via the diode 54. Therefore, the current from the resistor 40 does not flow through the secondary coil 44 to the transistor 46, but through the tertiary filter 45 to the transistor 47.
flows to

Collector-emitter voltage of transistor 46, collector-emitter voltage of transistor 47, and resistor 40
The voltages are as shown in Figure 3 (1), Figure 3 (2), Figure 3 (3).
) are shown respectively.

Therefore, the peak value of the collector-emitter voltage of the transistors 46 and 47 and the peak value of the voltage of the resistor 40 are fixed, and the magnetic multivibrator circuit 4 outputs the same waveform with the same peak value 20-. Derived sequentially.

Assume that a sufficient constant current (2), which is larger than the above-mentioned constant current (1), is caused to flow from the constant current sources 4.9 and 50. In this case, if the resistance value of the resistor 40 is R40 and the collector-emitter current of the transistors 4.6 and 4.7 is 2.\'cc/R40, that is, in the active region, the transistors 46°47 It cuts off sharply at different duty cycles and continues to oscillate. Therefore, the diodes 53, 54 . , 55, 56, the peak values of the collector-emitter 18 voltage of the transistors 46, 4.7 and the voltage of the resistor 4() are fixed, and the voltage from the magnetic multi-vib break circuit 4 is fixed. The outputs of the same waveform with the same peak value are sequentially derived.

In the duty detection circuit 5, when the transistor 46 of the magnetic multivibrator circuit 4 is conductive,
Current flows from constant current source 63 to transistor 46 via diode 6B. Therefore transistor 64. ．．
66 is cut off and transistor 65 is turned on. Capacitor 73 is charged via transistor 65, diode 67 and resistor 72.

When transistor 46 is cut off, diode 68 is cut off and the base voltage of transistor 64 becomes high. Once the transistors 64 and 66 are turned on, the transistor 65 is turned off. The capacitor 73 is the resistor 7
2 and transistor 66.

Similarly to the duty detection circuit 5, in the duty detection circuit 6, the capacitor 86 is connected to the resistor 8 depending on whether one transistor 47 of the magnetic multi-by-break circuit 4 is turned on or off.
Charge and discharge via 5. Capacitor 73.86
The voltages of ) are shown in FIG. 3(4) and FIG. 3(5), respectively.

The resistor 72 and the capacitor 73 are driven by the totem pole output corresponding to the duty from the magnetic multivabrator circuit 4, and the charging and discharging time constants are equal, so the charging voltage of the capacitor 73 is DC voltage +Vcc, -Vcc.
The resistor 85 and the capacitor 86 are driven by the 1-temball output corresponding to the duty from the magnetic multi-vibration circuit 4, and the charging and discharging time constants are equal. Therefore, the charging voltage of capacitor 86 is DC voltage \7cc, -\'
e Lower by one point based on 0\l, which is the intermediate value between 0. Therefore, the reference voltages of the outputs from the duty detection circuits 5 and 6 match, and there is no need to prepare a special reference voltage, and there is no need to make adjustments between the duty detection circuits 5 and 6.

In the differential amplifier circuit 7, the mutually opposite phase outputs from the duty detection circuits 5 and 6 are differentially amplified via operational amplifiers 75 and 88, respectively. The output of the differential amplifier circuit 7 is shown in FIG. 3 (6). Since the outputs from the duty detection circuits 5 and 6 are in opposite phases to each other, the detection sensitivity of the differential amplifier circuit 7 is doubled. Full wave rectifier circuit 1 of level discrimination circuit 8
At 01, full-wave rectification is performed to integrate the alternating current component of the signal from the differential amplifier circuit 7. The output from the full-wave rectifier circuit 101 is shown at 23- in FIG. 3 (7). In the time delay circuit 96 of the level discrimination circuit 8, a current flows through the resistor 119 so that the emitter voltage of the transistor 117 becomes a voltage corresponding to the output from the full-wave rectifier circuit 94. Transistor 121 is conductive and the current flowing through transistor 121 determines the leakage sensitivity current. The current flowing through the capacitor 1.20 is equivalent to the leakage current, and the time W for shutting off the relay switches 139 and 140 is determined depending on the leakage current. The current flowing through the transistor 121 revolves around the current flowing through the capacitor 120,
The charging voltage of the capacitor 120 is zero as shown in FIG. 3 (8) (the potential is -Vcc). The sum of the forward voltage of diode 128 and the Zener voltage of Zener diode 129 defines a first discrimination level. The forward voltage of diode 128 defines a second discrimination level that is less than the first discrimination level. When a leakage occurs and the charging voltage of the capacitor 12 () exceeds the first discrimination level, the output of the operational amplifier 126 becomes a high level (10 V cC). When the output of the operational amplifier 126 becomes high level 24-, the transistor 130 becomes conductive and the operational amplifier 1
26 performs level discrimination at the second discrimination level. Therefore, even if the voltage of the capacitor 120 decreases, the discrimination level decreases, and even leakage of distorted alternating current such as a phase control signal can be sufficiently detected.

Further, when the output of the operational amplifier 126 becomes high level, the transistor 191 becomes conductive, and the transistor 121 interrupts the W
fI is done. Therefore, no current flows through the transistor 121, and the capacitor 120 is charged by the current. As a result, even leakage of distorted alternating current can be sufficiently detected.

Note that since it is assumed that no leakage occurs, the output of the operational amplifier 126 is at a low level.

In the response circuit 9, the output from the level discrimination circuit 8 through the diode 132 is at a low level, so the transistor 135 is cut off, and the relay coil 138 of the trip relay 134 remains demagnetized as shown in Figure (9) of fJIJ3. . Relay switch 139, 14
0 remains conductive.

Next, the DC leakage occurs at time + as shown in Figure 4 (1).
Assume the case that occurs in 1. In this case, the collector-emitter voltage of each transistor 46, 47 and the voltage of the resistor 40 are as shown in FIG. 4 (2), FIG. 4 (3),
Each is shown in Figure (4).

When a leakage occurs, transistors 4 and 6 are activated according to the leakage current.
, the duty ratio of 4.7 changes from 50%.

This change in duty ratio corresponds to each duty detection circuit 5, 6.
detected by. The output voltage of the duty detection circuit 5 is shown in FIG. 4 (5), and the output voltage of the duty detection circuit 6 is shown in FIG. 41 (6).

Therefore, the output voltage of the differential amplifier circuit 7 becomes as shown in FIG. 4 (7), and the output voltage of the full-wave rectifier circuit 94 becomes as shown in FIG. 4 (8). Operational amplifier 116 derives an output signal such that the emitter of transistor 117 is equal to the output voltage of full-wave rectifier circuit 94 . Therefore, the voltage of the capacitor 120 gradually increases as shown in FIG. 4 (9). When the voltage on capacitor 120 exceeds the first discrimination level at time E2 after time W, operational amplifier 126
The output becomes high level. Therefore transistor 1
35 becomes conductive, and the relay coil 138 is excited as shown in FIG. 4 (10).

Therefore, the relay switch ] 39 , ] /1.0
The response device 9 is activated.

Then, as shown in FIG. 5(1), the AC current leakage occurs at time t.
Assume that the child is born in 3. In this case, the collector-emitter voltage of each transistor 46+47 is the fifth
These are shown in FIG. 5 (2) and FIG. 5 (3), respectively. Also the fifth
An enlarged view of the portion indicated by the arrow 2+')I, 202 shown in FIG. 5(4) is shown in FIG. 5(4).

When a leakage occurs, the transistor 46,
The duty ratio of 47 changes from 5()%.

This change in duty ratio corresponds to each duty detection circuit 5.6.
detected by. The output voltage of the duty detection circuit 5 is shown in FIG. 5(5)1, and the output voltage of the duty detection circuit 6 is shown in FIG. 5(6).

Therefore, the output voltage of the differential amplifier circuit 7 is as shown in FIG. 5 (27-(7)), and the output voltage of the aftermath rectifier circuit 94 is between the virtual line 2()3 and zero volts shown in FIG. 5 (8). The voltage \11 between is the voltage at which the capacitor 120 is discharged due to conduction of the transistor 121. In addition, the shaded part shown in FIG. 5 (8) is the capacitor 120.
is the charging current.

The operational amplifier 116 derives an output signal such that the emitter of the 1-run transistor 117 is equal to the output voltage of the full-wave rectifier circuit 94. Therefore, the voltage of the capacitor 120 gradually increases as shown in FIG. 5(9). capacitor 1
When the voltage of 20 exceeds the first discrimination level at time t4 after time W, the output of operational amplifier 126 becomes high level. Therefore, transistor 135 becomes conductive, and relay coil 138 is excited as shown in FIG. 5(10). Therefore, relay switch 139.1/IO is cut off,
The response device 9 operates.

Next, assume that a leakage of phase angle controlled distorted alternating current occurs at time t5 as shown in FIG. 6(1). In this case, the collector-emitter voltage of each transistor 46f428-7 is as shown in FIG.
Each is shown in Figure (3). When a leakage occurs, the duty ratio of transistors 46 and 47 increases depending on the leakage current.
Changes from 0%. This change in duty ratio is detected by each duty detection circuit 5, 6. The output voltage of the duty detection circuit 5 is shown in FIG. 6 (4), and the output voltage of the duty detection circuit 6 is shown in FIG. 6 (5).

Therefore, the output voltage of the differential amplifier circuit 7 becomes as shown in FIG. 6 (6), and the output voltage of the full-wave rectifier circuit 94 becomes as shown in FIG. 6 (7). Operational amplifier 116 derives an output signal such that the emitter of transistor 117 is equal to the output voltage of full-wave rectifier circuit 94 . Therefore, the voltage of the capacitor 120 gradually increases as shown in FIG. 6(8). When the voltage on capacitor 120 exceeds the first discrimination level at time t6 after time W, operational amplifier 126
The output becomes high level. Therefore transistor 1
35 becomes conductive, and the relay fill 138 is excited as shown in FIG. 6(9). Therefore, the relay switch 139
, 140 are shut off, and the response device 9 is activated.

Next, assume that the line 32 is cut at a point P shown in FIG. In this case, the current flowing through the load 1981 from the AC power supply 199 through the line 31 is
8 to line 32, terminal N, diode 27, line 39 of start circuit 3, load connected between line 39 and line 34, line 34, diode 30, resistor 2
2. AC power supply 1 via terminal PE and line 200
Return to 99. Therefore, in the saturable reactor 41, the currents flowing through the lines 31 and 32 are balanced, so that the response circuit 9 cannot be operated from the saturable reactor 41.

The power supply circuit 2 connects an AC power supply 199 to lines 3:1. ,
AC power between terminals T- and PE via 200 is converted into DC power. The current sensing device is therefore energized. The resistor 152 has a small amount, for example, 1 rl F1 μl, so that the voltage at the inverting input of the operational amplifier 151 is comparable to the voltage at the non-inverting input of the operational amplifier 151
~ current flows. The operational amplifier 151 amplifies the second slight current and supplies it to the full-wave rectifier circuit 55. The operations of the full-wave rectifier circuit 155 and the time delay circuit 149 are shown in FIG.
), Figure 3 (8), Figure 4 (7) to Figure 4 (10),
Figure 5 (7) to Figure 5 (9) and Figure 6 (6) to Figure 6
The operation is similar to that described in FIG. (8). Therefore, the output of operational amplifier 176 becomes high level, transistor 135 becomes conductive, and relay coil 138 is excited. Therefore, the relay switches 139 and 140 are cut off, and the response circuit 9 is activated. Further, even when a high voltage is applied to the current detection device 1, the response circuit 9 can be operated by the voltage detection circuit 10.

Figure 7 is circuit diagram 1 of the embodiment of the pond of the present invention, and diagram 2
Parts corresponding to the embodiments in the figures are designated by the same reference numerals.

In the start circuit 3()2 of the current detection device 301,
Between lines 33 and 34 there is a Zener diode 303,
A series circuit consisting of resistor 304 and 31-ener diode 305 and resistor 3
(A series circuit consisting of 16 + 3 + 17 is connected respectively. A series circuit consisting of a resistor 308 and a Zener diode 309 is connected between lines 39 and 34.

The cathode of the Zener diode 305 is connected to the operational amplifier 31.
Connected to the 0 non-inverting input. Resistor 306 and resistor 307
The connection point with is connected to the inverting input of operational amplifier 310. The resistor 306 includes a transistor 311 and a resistor 3.
A series circuit consisting of 12 is connected in parallel. The base of transistor 311 is connected to line 33 via resistor 313 and to the base of transistor 35 via resistors 314 and 315. The connection point between resistor 314 and resistor 315 is connected to the output of operational amplifier 310 via diodes 31.6 and 317 in the forward direction.

The cathode of the Zener diode 309 is connected to the operational amplifier 31.
8 non-inverting input.

The inverting input of operational amplifier 318 is connected to the output of operational amplifier 318 and grounded.

32- In one magnetic multivibrator circuit 40 resistors
A series circuit consisting of a resistor 32 () and a Zener diode 321 for detecting saturation of the saturable reactor 41 is connected in parallel. DC voltage + V e H - \tcc
A series circuit consisting of a transistor 322 and a resistor 322 is connected between the two. The base of transistor 322 is connected to the cathode of Zener diode 321.

The four constant current sources are connected to a DC voltage -Vcc via a forward diode 324 and a transistor 325 as a switching element. Constant current source 50 is connected to the collector of transistor 325 via forward diode 326.

The base of transistor 325 is connected to the collector of transistor 322.

In the time delay circuit 328 of the level discrimination circuit 327, a series circuit consisting of a resistor 127 and a plurality (four in the figure) of forward diodes 329 to 332 is connected between DC voltages +V'cc and -Vcc. The anode of diode 329 is connected to the inverting input of operational amplifier 12G. The cathode of diode 331 is connected to the collector of transistor 30. The forward voltage of diodes 329-322 defines a first discrimination level.

The forward voltages of diodes 329-331 also define a second discrimination level. A series circuit consisting of a resistor 333, a forward diode 334, and a resistor 335 is connected between the output of the operational amplifier 126 and the DC voltage -\7cc. The cathode of diode 334 is connected to transistor 1
Connected to 30 units.

In the time delay circuit 337 of the voltage detection circuit 336, a resistor 180 and a plurality of (
A series circuit consisting of four forward facing diode diodes 338 to 341 (shown in the figure) is connected.

The anode of diode 338 is connected to the inverting input of operational amplifier 76. The cathode of the diode 3\0 is connected to the transistor 77 (2\, 2). The forward voltages of diodes 338-341 define a first discrimination level. A second discrimination level is defined. Between the output of the operational amplifier 176 and the DC voltage -Vce,
Resistor 342, forward diode 3, 13 and resistor 3
A series circuit consisting of /l...1 is connected. The cathode of diode 343 is connected to the base of transistor 177.

Trip relay 13 = 1 relay switch 1391
When i 4 o is made conductive, AC power from the AC power supply 199 is supplied to the power supply circuit 2 . In the start circuit 302, when AC power is turned on, the transistor 35. :”
l + 1 is blocking. Therefore line 33. R
The DC voltage between /1 rises sharply to -. line 33.3
/I DC voltage \I'c, c.

-Vcc is applied to the operational amplifier 310, the response circuit 3], and the level discrimination circuit 8. zener diode 3
03 prevents the capacitor 24 from becoming abnormally high voltage.

The resistance values of the resistors 3 +'+ 6 , 3+) 7 , 312 are set equal to 50 Ω, for example. When the voltage between the lines 33 and 34 exceeds the Zener voltage of the Zener diode 305, the Zener diode 305 becomes conductive and the output of the operational amplifier 301 changes from high level to low level.

When the output of operational amplifier 310 becomes low level, transistors 35 and 311 become conductive. Therefore line 39
．． 34, a DC voltage of 1\' cc, -\7ee is steeply derived.

Furthermore, since the transistor 311 is conductive, the resistor 312 is connected in parallel to the resistor 306. Therefore, the voltage is divided by the resistors 306, 307, and 311, and the operational amplifier 3
The reference voltage applied to the inverting input of 10 becomes negative. Therefore, the output of operational amplifier 310 becomes difficult to change from low level to high level. The start circuit 302 outputs DC power at the voltage ET between the lines 33.34 and the voltage E2 (El>E2) of the line 33.34 open which is less than the voltage E1.
) to cut off the DC power. Therefore, AC power supply 201
The current detection device 301 is activated even after the occurrence of voltage fluctuation or interruption of AC power.

36- In the magnetic multivibrator circuit 319 (・, resistor 4
When the voltage at zero is low, the Zener diode 321 is cut off. Transistors 322 and 325 are therefore cut off. The current from constant current source 49 flows through diode 53 or diode 54 and does not flow through diode 324. Further, the current from the constant current source 5 ( ) flows through the diode 55 or the diode 56 and does not flow through the diode 326 . Saturable reactor 4
1 becomes saturated, the voltage across resistor 40 becomes high, and resistor 4 (
) exceeds the Zener voltage of Zener diode 321, Zener diode 324 becomes conductive.

When Zener diode 324 conducts, transistor 3
22 becomes conductive, and transistor 325 also becomes conductive. The current from the constant current source 4.9, 5 +1 flows through the diode 53.5
4 and diodes 55 and 56, all flows through diodes 324 and 326 to transistor 325. Therefore, both transistors 46 and 47, one of which was conducting, are cut off. It is now possible to make the peak values of the voltages of transistors 46 and 71.7 equal to each other.

FIG. 8 is a circuit diagram showing a magnetic multivibrator circuit 34G according to another embodiment of the present invention, and FIG.
The same reference numerals are used for parts corresponding to the embodiments in the figures. The magnetic multi-bye break circuits 3 and 16 replace the magnetic multi-bye break circuits 4 and 319 in the current detection device 1.
Or used in the current detection device 301. A transistor 3.17 as a switching element is connected between the emitters of each transistor 4.6 and 47 and DC voltage -Vce.
is connected. A series circuit consisting of a resistor 348 and 34 transistors is connected between the DC voltage elements \7cc and -\I'cc. The flipter of the transistor 322 is
It is connected to the base of transistor 349 via resistor 350.

In the magnetic multi-vib break circuit 346, the resistance /I
When the voltage at O is low, Zener diode 321 is cut off. Therefore, trans 9q-17 becomes conductive. Current from constant current source 49 flows through diode 53 or diode 54, current from constant current source 5() flows through diode 56, and either one of transistors 46 and 47 becomes conductive. When the voltage across resistor 40 becomes high and the voltage across resistor 4 exceeds the Zener voltage of Zener diode 3, Zener diode 324 becomes conductive.

When Zener diode 321 becomes conductive, transistor 3
22, :'! , 1.9 conducts and transistor 3
47 is blocked. Therefore, one of the transistors 46, 4. , 7 are both blocked.

Therefore, it is possible to make the peak values of the voltages of transistors 4.6 and 4.7 equal to each other.

As described below, according to the present invention, since the resistor and capacitor are driven by a totem pole output according to the duty, there is no need to provide a special reference voltage.
However, the time constants during charging and discharging match.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a prior art duty detection circuit, and FIG.
The figure is a circuit diagram of one embodiment of the present invention, Figures 3 to tJIJ6 are diagrams for explaining its operation, Figure 7 is a circuit diagram of another embodiment of the present invention, and Figure 8 is a circuit diagram of another embodiment of the present invention. FIG. 7 is a circuit diagram showing a magnetic multi-byte break circuit 346 of another embodiment. 1, 301... Current detection device, 4,319,346
...Magnetic multi-vibration circuit, 5,6...Duty detection circuit, 7...Differential amplifier circuit, 8,327.
...Level discrimination circuit, 9...Response circuit, 31.32.
...Line, 4.0, 72, 85...Resistance, 41
...Saturable reactor, 44...Secondary coil, 45
...Tertiary coil, 65,66.78.79...Transistor, 67.81...Diode, 73.86...
... Capacitor agent Patent attorney Kei Nishi Part 40 - Figure 1 Figure 3 - VCC Figure 4 (7) o□ (9) tl t2

Claims (1)

[Claims] Object to be detected 11) A saturable reactor that is provided in connection with a line through which current flows and has secondary and tertiary coils for detecting the current to be detected, detecting the current flowing in the secondary and tertiary coils. A magnetic multi-by-break circuit is formed by a resistor for detecting the current and a multi-by-by break circuit that oscillates while changing a duty of a predetermined period according to the current to be detected, and a pair of duty detection circuits are provided for detecting the respective duties, In a current detection device that discriminates the level of the mutual difference between the outputs corresponding to the duty from each duty detection circuit and operates a response circuit when the discrimination level is exceeded,
Current detection characterized in that each of the duty detection circuits is driven by a totem pole output according to the duty and each has a resistor and a capacitor different from the single resistor for detecting the duty. Device.