JP2621934B2 - Delay type earth leakage breaker - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a delay type earth leakage breaker that shuts off power when an earth leakage is continuously detected for a predetermined time.

[Conventional technology] As for the earth leakage breaker, more than 99% are high speed type.
There are very few delay type earth leakage breakers. FIG. 6 shows a high-speed earth leakage breaker. In this high-speed circuit breaker, the output of a zero-phase current transformer ZCT for detecting a leakage current is amplified by an amplification / comparison circuit section 1 and an intermittent output generated when the amplified output is equal to or higher than a predetermined voltage is used as a capacitor C _0. When the voltage between both ends of the capacitor C ₀ becomes equal to or higher than a predetermined voltage, SCRQ ₀ connected in series to the exciting coil L of the earth leakage breaker main body is turned on by the comparison output circuit section 2 and the exciting coil L An exciting current is passed to open the switching contact r. The power of each unit is supplied from the power supply circuit 3. Note that a circuit including the amplification / comparison circuit section 1 and the comparison output circuit section 2 is implemented as an IC. Conventionally, this high-speed earth leakage breaker
As shown in FIG. 7, a delay-type earth leakage breaker is constructed by adding a comparison delay circuit unit 4 externally. The added comparison delay circuit unit 4 may be configured using another IC,
The number of components is increased due to the configuration using a discrete circuit. Therefore, there has been a problem that the size of the delay type earth leakage breaker increases and the cost increases. Therefore, the added comparison delay circuit unit 4 is also integrated with the circuit units 1 and 2
It is conceivable to reduce the number of parts by using C, but as described above, this delay type earth leakage breaker has a problem that the production quantity is extremely small, there is no merit of scale, and the cost increases when IC is used. .

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned points, and an object of the present invention is to reduce the number of components by using an IC, and to provide an inexpensive delay-type earth leakage. To provide a breaker.

[Means for Solving the Problems] In order to achieve the above object, the present invention determines that a leakage has occurred and generates a detection output when a period in which an input from a zero-phase current transformer is equal to or higher than a reference voltage continues for a specified time or more. A leakage detection circuit section, an output circuit driven by the detection output of the leakage detection circuit section to turn on the switching element and supply an exciting current to an exciting coil of the earth leakage breaker body, and a constant period during which the input voltage is equal to or higher than a predetermined voltage. A comparison delay circuit unit that turns on the switching element through the output circuit when the ratio within the time is equal to or more than a predetermined value, and an input of an output of the leakage detection circuit unit to the output circuit is prevented. A control circuit for supplying an input voltage equal to or higher than the predetermined voltage to the comparison delay circuit when the input is equal to or higher than the reference voltage.

(Operation) As described above, the present invention provides a leakage detection circuit unit that determines that a leakage has occurred and generates a detection output when a period in which the input from the zero-phase current transformer is equal to or higher than the reference voltage continues for a specified time or more. An output circuit driven by the detection output of the detection circuit unit to turn on the element for switching and to supply an exciting current to the exciting coil of the earth leakage breaker main body, so that the leakage of the high-speed earth leakage breaker can be detected by these circuit units. And a comparison delay circuit unit that turns on a switching element through the output circuit when a ratio within a certain period of time during which the input voltage is equal to or higher than a predetermined voltage is equal to or higher than a predetermined value. The voltage of the neutral line of the single-phase three-wire power supply line is input to the comparator, and this comparison delay circuit can be used as an open-phase detection circuit for detecting the open phase of the neutral line. In addition, the input of the output of the leakage detection circuit unit to the output circuit is prevented, and when the input to the leakage detection circuit unit is equal to or higher than the reference voltage, the input voltage equal to or higher than the predetermined voltage is applied to the comparison delay circuit unit. By providing the control circuit, a delay-type earth leakage breaker can be configured using the entire circuit. In other words, the circuits other than the control circuit of the delay type earth leakage breaker can be shared with the high-speed earth leakage breaker, and the common circuit section can be integrated into an IC to reduce the number of parts. By being able to share, it is designed to provide economies of scale and to be inexpensive.

(Embodiment) FIGS. 1 to 5 show an embodiment of the present invention. In this embodiment, if the circuit of the delay type earth leakage breaker can be shared with the high-speed earth leakage breaker, there is a scale advantage,
It focuses on the fact that it can be integrated into an IC, and the above-described comparison delay circuit section 4 of the conventional delay type earth leakage breaker detects the open phase of the neutral line of the high-speed earth leakage breaker for a single-phase three-wire power supply line. This is used as an open phase detection circuit.

The delay type earth leakage breaker of the present embodiment has an earth leakage detection circuit unit 12 for a high-speed earth leakage breaker, and turns on SCRQ ₀ driven by the detection output of the earth leakage detection circuit unit 12 to excite the excitation coil L of the earth leakage breaker body. An output circuit 8 for flowing a current, and detecting that an input voltage has become a predetermined voltage or more,
A comparison delay circuit unit that generates an output when the state in which the input voltage is equal to or higher than a predetermined voltage continues for a predetermined time or more. The leakage detection circuit 12 includes an amplifier 5 that amplifies the output of the zero-phase current transformer ZCR that detects a leakage current, and an amplifier 5 that amplifies the output.
Becomes the output comparator 6 which compares the reference voltage, the capacitor C ₁ the output of the amplifier 5 is charged by the output of the time is not less than the reference voltage of the comparator 6, the voltage across the capacitor C ₁ is a predetermined voltage or higher And a one-shot circuit 7 that generates an output when the signal is output. The output circuit 8
Is driven by the output of the one-shot circuit 7, and at this time SCRQ
Turn on ₀ . The comparison delay circuit 4 includes a comparator 9 for comparing the input voltage reference voltage, typically a capacitor C ₂ is discharged when the above there is an input voltage is the reference voltage to the charge state, the voltage across the capacitor C ₂ a waveform shaping circuit 10 for waveform shaping, a capacitor C ₃ to the voltage across the capacitor C ₂ is charged when below the threshold voltage of the waveform shaping circuit 10, the output when the voltage across the capacitor C ₃ has reached the predetermined voltage And a delay circuit 11 for turning on the circuit 8. The leakage circuit 12 and the output circuit 8
And the circuits within the dashed line frame including the comparison delay circuit 4 are integrated into ICs. Power for each circuit of the IC 15 is supplied from the constant voltage circuit 14.

FIG. 3 shows a circuit diagram of a high-speed earth leakage breaker manufactured by using the above IC15. First, the operation of detecting electric leakage of the high-speed leakage breaker will be described. Leakage current is zero phase current transformer ZCT 1
When it occurs on the secondary side, a leakage signal voltage _VL appears on the secondary side.
This leakage signal voltage _VL is amplified by the amplifier 5 as shown in FIG. The output of the amplifier 5 is an output that is swung in both the positive and negative relative to the bias voltage V _B. In half cycle in which the output of the amplifier 5 is negative, the reference voltage V _r1 to become the period following the comparator 6, the capacitor C ₁ is charged. Note that when the leakage current is small, the period during which the output _{VL of the} amplifier 5 is less than or equal to the reference voltage _Vr1 of the comparator 6 during the half cycle in which the output is negative is short, and therefore, as shown on the left side of FIG. The voltage V _C1 across the capacitor C ₁ does not reach the threshold voltage V _{TH1 at} which the one-shot circuit 7 turns on. At this time, the capacitor C ₁
In the When charging is completed more current than charging current at the same time, to discharge the charged electric charge of the capacitor C _1. Further, when the leakage current is large, the period during which the output _{VL of the} amplifier 5 is less than or equal to the reference voltage _Vr1 of the comparator 6 during a half cycle in which the output is negative is long, and therefore, as shown on the right side of FIG. The voltage V _C1 across C ₁ reaches the first threshold voltage V _TH1 by the one-shot circuit 7. Therefore, the output circuit 8 by the output of one-shot circuit 7 at this time is turned on, the output V _O of the high level shown in FIG. 4 (c) is output. In this case, the discharge capacitor C ₁ with a small current. Then, the first threshold voltage V of the one-shot circuit 7
When the voltage across V _C1 of capacitor or C ₁ drops to the second threshold voltage V _TH2 is lower than _TH1, the output V _O of the output circuit 8 becomes low. In other words, during the period t ₂ of FIG. 4 (c), the output V _O of the output circuit 8 is at the high level, performs the blocking operation of the power supply by turning on the SCRQ ₁ This output V _O. In such a high-speed type earth leakage breaker, and has a leakage current impressed current when period the amplitude of the output V _L of the amplifier 5 is not less than the reference voltage V _r1 of the comparator 6 is equal to t ₁ in Figure 4.

When the comparison delay circuit 4 is used as a circuit for detecting the neutral phase N of a neutral line N of a high-speed earth leakage breaker for a single-phase three-wire power supply, a voltage obtained by dividing the voltage of the neutral line N of the power supply line 1 by a resistor. V _N
Is input to the comparator 9. This voltage V _N is usually the fifth
The waveform has a uniform amplitude as shown on the left side of FIG. Now, the voltage V _N by the load state of the power line l When the neutral line N is broken has a waveform amplitude as shown on the right side of FIG. 5 (a) is large and small alternately. Therefore, when the disconnection of the neutral line N occurs, the amplitude of the voltage V _N is are adjusted the resistor divider value to be equal to or greater than the reference voltage V _r2 of the comparator 9. Therefore, when the disconnection of the neutral wire N occurs, occurs a period in which the amplitude of the voltage V _N becomes equal to or higher than the reference voltage V _r2 of the comparator 9, to discharge the capacitor C ₂ in the charged state in this period intermittently. Incidentally, the capacitor C ₂ is are to be charged with the discharge period as shown in FIG. 5 (b) is terminated. The voltage V _C2 across the capacitor C ₂ is the waveform shaping circuit 10
For it is the threshold voltage V _TH3 or less, the charging of the capacitor C ₃ is started as shown in FIG. 5 (c).
The voltage V _C3 across the capacitor C ₃ is applied to the delay circuit 11
When the threshold voltage V _TH4 reaches the threshold voltage V _TH4 , the output circuit 8 is driven by the output of the delay circuit 11, and the output V _O goes high, and the power supply is cut off in the same manner as in the case of the electric leakage. By the way, as shown in FIG. 5 (a), there is a case where a single noise NP is superimposed on the neutral line N, and this single noise NP portion becomes equal to or higher than the reference voltage _{Vr2 of the} comparator 9. In this case, Before the voltage V _C3 across the capacitor C ₃ reaches the threshold voltage V _TH4 of the delay circuit 11, the voltage V _C2 across the capacitor C ₂ becomes equal to or higher than the threshold voltage V _TH3 of the waveform shaping circuit 10, and the capacitor C ₃ is charged. Since the operation is stopped, a malfunction due to the single noise NP does not occur.

When the leakage is detected by the IC 15 as described above, a signal for immediately turning on the output circuit 8 is output to the leakage detection circuit unit 12 of the high-speed leakage breaker. Thus, the output circuit 8
The condition for outputting a signal for turning on the capacitor is the voltage V _C1 across the capacitor C ₁ and the threshold voltage V _{C1 of the} one-shot circuit 7.
_{This is when TH1} (about 1.8V) is reached. Thus, if both end voltages V _C1 above the threshold voltage V _TH1 clamp below the capacitor C _1, the output circuit 8 is not turned on. Also,
Since there is a leakage is seen by the voltage across V _C1 of the capacitor C ₁ is increased, the voltage across V _C1 of the capacitor C ₁
By operating the comparison delay circuit unit 4 when the voltage rises to a predetermined voltage, a delay-type earth leakage breaker can be obtained.
Therefore, a transistor Q ₁ which is turned on when it reaches a voltage across the base-emitter voltage of the capacitor C ₁ as of FIG. 1 in this embodiment, the transistor Q ₂ to which is turned on when the on transistor Q _1, the transistors are connected in series Q _2, transistor Q ₂ is formed of a resistor R _1, R ₂ Prefecture for inputting a power supply voltage when turned on comparator 9 of the comparator delay circuit a rectifying and smoothing the supply voltage divided by the control circuit 13 to I
In addition to C15, a delay type earth leakage breaker is configured.

When a leakage current is detected by the zero-phase current transformer ZCT as shown in FIG.
C ₁ is charged. When used as the delayed type earth leakage breaker, the transistor Q ₁ at both ends of the capacitor C ₁
Because the base and emitter of the
The voltage V _C1 across C ₁ is clamped to the base-emitter voltage of the transistor Q ₁ of about 0.6 V, and the output of the one-shot circuit 7 does not occur. The voltage V _C1 across the capacitor C _{1 at} this time is shown in FIG. Thus capacitor C ₁
End voltage V _C1 is becomes the base-emitter voltage of the transistor Q _1, the transistor Q ₁ is turned on for. For this reason,
The transistor Q _{2 is} also turned on, and the voltage V _{1 obtained} by dividing the power supply voltage obtained by rectifying and smoothing the power supply voltage with the resistors R ₁ and R ₂ is input to the comparator 9. This input voltage is shown in FIG. Here, when the power supply voltage of the power supply voltage by rectifying and smoothing the V _S, the peak value of the input voltages V ₁ becomes _{V 1 = R 1 / R 1} + R 2 × V S. The input voltages V ₁ is the reference voltage V of the comparator 9
Yes set to exceed _r2, as in the case of the description of the operation of the open phase detection circuit described above, the capacitor C ₂ as shown in (d) of FIG When the input voltage V ₁ is inputted intermittent discharge Is done. Thus, the capacitor C ₃ as shown in FIG. 2 (e)
Is maintained, and after a predetermined time, the output circuit 8 is turned on by the output of the delay circuit 11 ((f) in the same figure), turning on the SCRQ ₀ and shutting off the power supply line l to operate as a delay type earth leakage breaker. Do. As described above, according to the present embodiment, the IC 15 can be shared by the high-speed earth leakage breaker and the delay earth leakage breaker, so that the number of components is reduced. In addition, since the high-speed earth leakage breaker and the above IC 15 can be shared, economies of scale can be obtained and the cost can be reduced.

[Effects of the Invention] As described above, according to the present invention, a leakage detection circuit unit that determines that a leakage has occurred and generates a detection output when a period in which an input from a zero-phase current transformer is equal to or more than a reference voltage continues for a specified time or more, An output circuit driven by the detection output of the earth leakage detection circuit unit to turn on the switching element and supply an exciting current to the exciting coil of the earth leakage breaker body, so that these circuits detect the earth leakage of the high-speed earth leakage breaker. And a comparison delay circuit unit that turns on a switching element through the output circuit when a ratio within a certain period of time during which the input voltage is equal to or higher than a predetermined voltage is equal to or higher than a predetermined value.
A voltage of a neutral line of a single-phase three-wire power supply line is input to the comparison delay circuit unit, and the comparison delay circuit unit can be used as an open phase detection circuit for detecting an open phase of the neutral line. Further, a control circuit for preventing the input of the output of the leakage detection circuit to the output circuit, and for providing an input voltage equal to or higher than the predetermined voltage to the comparison delay circuit when the input to the leakage detection circuit is equal to or higher than the reference voltage. With this configuration, a delay-type earth leakage breaker can be configured using the entire circuit. In other words, the circuits excluding the control circuit of the delay type earth leakage breaker can be shared with the high-speed earth leakage breaker, so that the number of parts can be reduced by making the common circuit part an IC, and the above-mentioned IC can be shared with the high-speed earth leakage breaker. In addition, there is an effect that a scale advantage is obtained and the cost is reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of the above, and FIG. 3 is a circuit section when a high-speed earth leakage breaker is manufactured using the IC of the above. FIG. 5 is a diagram for explaining the operation of the above, FIG. 6 is a circuit diagram of a high-speed earth leakage breaker, and FIG. 7 is a circuit diagram of a conventional delay earth leakage breaker. 4 is a comparison delay circuit unit, 8 is an output circuit, 12 is a leakage detection circuit unit, 13 is a control circuit, and ZCR is a zero-phase current transformer.

Claims (1)

(57) [Claims] An electric leakage detection circuit for generating a detection output by judging an electric leakage when a period in which the input from the zero-phase current transformer is equal to or higher than a reference voltage for a prescribed time or more, and a detection output of the electric leakage detection circuit An output circuit driven by the switching element to turn on the switching element to supply an exciting current to the exciting coil of the earth leakage breaker main body; and the output circuit when a ratio of an input voltage being equal to or higher than a predetermined voltage within a certain time is equal to or higher than a predetermined value. A comparison delay circuit section that turns on the switching element through
A control circuit for preventing input of the output of the leakage detection circuit to the output circuit, and for providing an input voltage equal to or higher than the predetermined voltage to the comparison delay circuit when the input to the leakage detection circuit is equal to or higher than the reference voltage. A delay type earth leakage breaker, comprising: