KR200276722Y1 - Circuit-breaker utilizing current transformer - Google Patents

Abstract

The present invention is to provide a circuit breaker for a distribution line using a current transformer that allows the selective use of the current capacity by constructing a multi-stage electronic circuit breaker while maintaining the advantages of the existing earth leakage breaker circuit operating in a physical manner. Rectifying means for rectifying a part of the power source by direct current; An electric shut-off means for selectively blocking current flowing through the rectifying means driven according to an applied current; Current detecting means for detecting the level of the load current passing through the load-side inlet line of the current passing through the electric shut-off means; Reference setting means for setting a reference current proportional to the load current by receiving the load current detected by the current detection means; Comparative amplifying means for comparing and amplifying the reference current set by the reference setting means and the DC current rectified by the rectifying means; According to the current output from the comparative amplification means or the load current detected by the current detecting means, the AC power passing through the rectifying means is selectively applied to the electric shut-off means to block the AC power input to the load side. The current transformer has high current detection accuracy, which improves the accuracy of response to load current, enabling immediate response to load changes, and provides advantages such as reliability of earth leakage circuits according to existing physical methods. It is possible to select and use the current capacity by constructing a multi-level electronic blocking circuit while maintaining.

Description

Distribution Line Circuit Breaker Using Current Transformers {CIRCUIT-BREAKER UTILIZING CURRENT TRANSFORMER}

The present invention relates to a circuit breaker for a distribution line, and more particularly to a circuit breaker using a current transformer to immediately respond to the sense current.

In general, excessive current flows into the power supply system due to various causes. In response to the instantaneous or continuous inflow of excess current, a power cut-off device is installed to protect the equipment, facility or life on the load side. In particular, a circuit breaker for a distribution line is provided on the load side of the distribution system so as to be suitable for the blocking of excessive current.

Distribution line breakers are designed to react instantaneously to currents exceeding the rated current range from 220V to 480V.

Hereinafter, terms used will be described.

Current transformer (or CT) is a device for obtaining a small current proportional to the large current of the alternating current. The main part of the current transformer structure is the winding of the primary coil with a small number of turns and the secondary coil with a large number of turns on a stratified core such as a transformer. The secondary coil connects an ammeter, a power meter and a relay. The current ratios of the primary and secondary are similar to the inverse of the number of coil turns, respectively. The rated value of the primary current varies from tens of amperes to thousands of amperes, but the rated current of the secondary current is mostly 5A. When connecting the current transformer to the circuit, the secondary coil is grounded and the primary coil provides sufficient insulation depending on the voltage. In the current transformer, the main part is put in the tank, and the oil-filled inflow type and the oil-free dry type are used for the circuit voltage of about 20,000 V or less. It is not advisable to put many instruments in series at the secondary when operating a current transformer. How much of the instrument can be connected depends on the rating of each current transformer.

A short circuit (or short circuit) is a condition where the load-side current is infinite and the voltage is 0V. At this time, a rapid inrush current is generated.

The video current is a current flowing when indoor wiring or electrical appliances cause a poor insulation against the earth. Correspondingly, the image voltage is defined.

A leakage current (leakage current) is a state in which leakage current flows due to a failure of a distribution line. Normally, since the distribution line is grounded on one phase, insulation failure occurs on the load side of the commercial power supply, a leakage current of about 5 to 100 mA flows depending on the ground resistance. Since such leakage current appears only on one side, an output proportional to the leakage current is obtained.

Overcurrents are currents above the rated current of the appliance (eg 30 A).

The conventional circuit breaker or earth leakage breaker related to the present invention operates in a physical manner, that is, a thermal type. Many of them adopt current thermal expansion method, which blocks the current only when it reaches the thermal expansion coefficient, and it is very dull to sense the load current because the blocking current is not uniform. Therefore, there is a problem that the ability to deal with the load immediately.

The present invention was created to solve the above-mentioned conventional problems, and an object of the present invention is to select and use a current capacity by constructing a multi-stage electronic blocking circuit while maintaining the advantages of the existing ground fault interrupting circuit operating in a physical manner. It is to provide a circuit breaker using a current transformer to enable this.

The circuit breaker for a distribution line using the current transformer of the present invention for achieving the above object, the rectifying means for rectifying the DC portion of the input AC power source; An electric shut-off means for driving according to an applied current to selectively block a current passing through the rectifying means; Current detecting means for detecting the level of the load current passing through the load side inlet line of the current passing through the electric shut-off means; Reference setting means for setting a reference current proportional to the load current by receiving the load current detected by the current detection means; Comparison and amplifying means for comparing and amplifying the reference current set by the reference setting means and the DC current rectified by the rectifying means; According to the current output from the comparison amplification means or the load current detected by the current detecting means for selectively applying the AC power passing through the rectifying means to the electric shut-off means to cut off the AC power input to the load side It characterized in that it comprises a blocking detection means.

1 is a block diagram of a circuit breaker for a distribution line using a current transformer according to an embodiment of the present invention.

2 is an application block diagram of a circuit breaker using a current transformer according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

110: AC power input unit 120, 170: rectifier

130: earth leakage detection circuit unit

140: isolation solenoid and earth leakage test switch

150: cutoff switch unit 160: load side current detection current transformer

180: reference part 200: multi-stage amplification part

210: DIP switch

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment according to the present invention.

This embodiment constitutes a multi-level electronic blocking circuit while excluding physical operation structures such as thermal methods while maintaining the advantages of the conventional methods used for earth leakage blocking circuits and the like. It is to implement a circuit breaker for a distribution line that selects and uses the required current capacity by using the multi-stage electronic blocking circuit.

1 is a block diagram of a circuit breaker for a distribution line using a current transformer according to an embodiment of the present invention.

As shown in FIG. 1, the circuit breaker of the present embodiment includes an AC power input unit 110, a first rectifying unit 120, an earth leakage blocking circuit 130, a blocking solenoid and an earth leakage test switch unit 150, and a disconnecting switch unit ( 150), the load-side current detection transformer 160, the second rectifier 180, the reference unit 180, the multi-stage amplifier 200, and a dual inline pin (DIP) switch 210.

The AC power input unit 110 is a portion to which AC power of 220V to 480V is supplied.

The first rectifier 120 rectifies the DC power supplied from the AC power input unit 110 to supply DC power to the earth leakage breaking detection circuit 130 and the multi-stage amplifier 200.

The earth leakage breaking detecting circuit unit 130 detects a leakage current with a current transformer CT to operate the blocking solenoid. When the leakage current (leakage) occurs, the ground fault interruption detection circuit 130 operates to rectify and amplify the video voltage of the current transformer to apply the thyristor gate current to latch the thyristor.

The blocking solenoid and the earth leakage test switch unit 150 block trip in response to the thyristor output of the earth leakage breaking detection circuit unit 130. The earth leakage test switch is a switch for checking the earth leakage blocking function by pressing once every fixed period (usually 1 month). One end of the blocking solenoid is always connected to one end of the output of the first rectifying unit 120, and the other end thereof is connected to the earth leakage blocking circuit unit 130 and one end of the earth leakage test switch. The other end of the output of the first rectifier 120 is connected to the other end of the ground fault test switch.

The cutoff switch unit 150 cuts power against a short circuit, an overcurrent, and a short circuit by utilizing a conventional cutoff switch as it is.

The load-side current detecting transformer 160 is for detecting a load current. In general, the load current detection method includes a current transformer method and a current multiplier amplification method, but adopts a current transformer method in consideration of safety.

The second rectifier 180 rectifies the current transformer voltage to supply a DC current to the reference unit 180.

The reference unit 180 receives the current of the second rectifier 180 to set a reference current proportional to the load current. The load maximum current and the minimum current can be set according to the current setting of the reference unit 180.

The multi-stage amplifier 200 drives the thyristor gate of the ground fault interruption detection circuit 130 according to the selection of the maximum current of the DIP switch to immediately shut off the over current. The multi-stage amplifier 200 may be implemented with a plurality of OP amplifiers, and may include a transistor for controlling the output at its output terminal.

The DIP switch 210 is a switch for preventing damage and fire of the device from overcurrent by selecting a current proportional to the maximum current of the electric and electronic device.

The condition that the input power is cut off by the circuit breaker for the distribution line in the distribution system is a leakage current or a short circuit on the load side and an overcurrent inflow from the input side. The overcurrent at this time means the continuous inflow of current exceeding the load side rated current.

In this configuration, the input power is applied to the first rectifying unit 120 via the AC power input unit 110. The DC power generated by the rectification of the AC power in the first rectifying unit 120 is applied to the earth leakage blocking circuit unit 130, while the AC power is applied to the blocking solenoid and the earth leakage test switch unit 150.

The blocking solenoid and the earth leakage test switch unit 150 block or pass the input power under the control of the earth leakage breaking detection circuit unit 130. Power passing through the blocking solenoid and the ground fault test switch unit 150 is applied to the load side via the blocking switch unit 150. In this way, power is supplied from the distribution system to the load side.

At this time, in order to detect leakage current, short circuit and over current in connection with the interruption of the input power, current detection using a current transformer is performed at the final input path to the load side.

Referring to the operation for each condition that the blocking is performed for the load side protection is as follows.

First, the operation corresponding to the overcurrent will be described.

When the load-side electrical appliance is used at a rated current (eg, 30 A) or more, that is, in the overcurrent state, the detection current value of the load-side current detection transformer 160 increases. The current value detected by the load-side current detecting current transformer 160 is converted into direct current by the second rectifying unit 180 and then applied to the reference unit 180. When the load-side current detecting current transformer 160 directly detects the load-side current, an appropriate magnification circuit may be configured according to a method well known in the art.

The reference unit 180 sets a reference value according to the current value detected by the load-side current detection transformer 160. The reference unit 180 sets a value corresponding to the rated maximum current and the rated minimum current as reference values in consideration of the rated current of the load side and the current-voltage characteristics of the current transformer.

In this embodiment, the reference value of the reference unit 180 is set to 10A, 20A, 30A, and the like. The current value set by the reference unit 180 is applied to the multi-stage amplifier 200. The DC current applied from the reference unit 180 is applied to the OP amplifiers for 10A, 20, and 30A in the multi-stage amplifier 200, and then from the first rectifier 120 by the respective OP amplifiers. Compared with the applied DC input power, it is multi-stage amplified.

The current value amplified by the multi-stage amplifier 200 is applied to the ground fault interruption detection circuit 130 to control whether the blocking solenoid is driven according to the overcurrent.

Here, the maximum current of the load side equipment should be considered to prevent overcurrent. Thus, the breaker user can select a current proportional to the maximum current of the load-side equipment using the DIP switch. The DIP switch has a function of selecting any one of 10A, 20A, and 30A. The operation of the DIP switch serves to selectively connect the output of each OP-amplifier in the multi-stage amplifier 200 to the ground fault interrupt detecting circuit unit 130. The control current is applied from the multi-level amplification unit 200 to the earth leakage breaking detection circuit unit 130.

For example, when the DIP switch 210 is selected as 30 A, the output of the 30 A OP amplifier of the multi-stage amplifier 200 is applied to the ground fault interrupt detecting circuit unit 130 as a control current. The ground fault detecting circuit unit 130 drives the blocking solenoid of the blocking solenoid and the ground fault test switch unit 150 to cut off the power input to the load side when the control current is introduced.

Next, the operation corresponding to a short circuit or a short circuit will be described.

When a short circuit occurs, the current value suddenly changes on each line of the distribution line (eg, two lines). Therefore, at the current input to the load side, the load-side current detection transformer 160 is installed at both ends of the distribution line to detect the passing current value. The detected current value may indicate a sudden increase due to a short circuit.If a current level of a predetermined level is set in advance, and the current value detected by the load-side current detection transformer 160 exceeds the set level, it is determined to be a short circuit. If you can. This detection method also applies to short circuits.

Therefore, when a short circuit or short circuit is determined based on the detection current value of the load-side current detection transformer 160, the ground fault interruption detection circuit unit 130 drives the interruption solenoid and the interruption solenoid of the earth leakage test switch unit 150 to input power. Allow blocking of

On the other hand, circuit breakers for distribution lines should be able to check the operating state at a certain time. Therefore, an earth leakage test switch is provided in the isolation solenoid and the earth leakage test switch unit 150 to artificially manipulate the interruption between the connection line from the earth leakage interruption detection circuit unit 130 to the isolation solenoid and the input line of the first rectifying unit 120. Make sure

The earth leakage test switch is normally open, and when closed for inspection, power passing through the first rectifying unit 120 is supplied to the blocking solenoid. Therefore, the blocking solenoid is energized to drive the input power. After the current supply is made from the earth leakage test switch by replacing the current supply from the earth leakage blocking circuit 130, it is possible to check the operation state accordingly.

The blocking solenoid returns when the applied current decreases below a certain level. The input power is resupplied due to the return of the isolation solenoid. This is equivalent to automatic return. Automatic return is effective in case of a short circuit or a short circuit.

In addition, there is a blocking switch unit 150 for manually blocking the load-side power input. The blocking switch unit 150 is to supplement the electronic blocking operation by the blocking solenoid of the blocking solenoid and the ground fault test switch unit 150. For example, in the case of a continuous short circuit or short circuit, the blocking solenoid is stopped and returned. In order to prevent excessive repetition of the operation is to manually open the cutoff switch unit 150.

2 is a block diagram illustrating an application state of the present invention.

The application example shown in FIG. 2 is applied to a so-called 'multi-tap outlet' having a multi-tap outlet, and the load side current detecting current transformer on the conductor 312 connecting between each outlet hole 311 in the outlet portion 310 ( 322). The load-side current detecting current transformer 322 is installed in such a proper position, and the other components as described in the first embodiment are placed in the switching block 320. In this case, since a plurality of tabs of the outlet may be provided, the load-side current detecting transformer 322 may be provided in consideration of the number of the outlet holes 311.

In the case of an outlet applied to a commercial power supply, it is common to have a rated current of 15A, so that the DIP switch 324 can select one of 5A, 10A, and 15A. Since the DIP switch 324 selects 5A, 10A, and 15A, the multi-stage amplifier 200 (see FIG. 1), which is not shown, is configured as an OP-amplifier for 5A, 10A, and 15A, and the reference unit 190, FIG. 1), reference currents may be set at 5A, 10A, and 15A.

In addition, the display lamp 326 displays how much the rated current is set according to the operation of the DIP switch 324 for the convenience of the user. Then, for the manual shut-off and return by the user's selection, a disconnect switch 328 is provided as in the first embodiment.

Thus, by implementing a simple circuit breaker and applying it to a commercial power outlet, it is possible to effectively protect the load-side equipment or human life from leakage current, short circuit, and over current.

The embodiments described above fall within the scope of various changes, modifications, and equivalents of the present invention. Therefore, the present invention is not limited to the description of the embodiments.

According to the circuit breaker for current distribution lines using the current transformer of the present invention, by adopting a current transformer with high current detection accuracy, the accuracy of the response to the load current is improved, and it is possible to immediately cope with the load change, and the circuit breaker according to the existing physical method It is possible to select and use the current capacity by constructing a multi-level electronic blocking circuit while maintaining the advantages such as the reliability of the circuit.

Claims (4)

Rectifying means for rectifying a portion of the AC power input; An electric shut-off means for driving according to an applied current to selectively block a current passing through the rectifying means; Current detecting means for detecting the level of the load current passing through the load side inlet line of the current passing through the electric shut-off means; Reference setting means for setting a reference current proportional to the load current by receiving the load current detected by the current detection means; Comparison and amplifying means for comparing and amplifying the reference current set by the reference setting means and the DC current rectified by the rectifying means; According to the current output from the comparison amplification means or the load current detected by the current detecting means for selectively applying the AC power passing through the rectifying means to the electric shut-off means to cut off the AC power input to the load side Distribution line breaker using the current transformer, characterized in that it comprises a blocking detection means. The method of claim 1, wherein the power blocking means, A solenoid part operated according to an applied alternating current; And a leakage test switch for selectively applying an AC power passing through the rectifying means on the current inflow line from the interruption detecting means to the solenoid part. The method of claim 1, And a disconnection switch unit for manually opening and closing the line according to the operator's selection between the electric shutoff means and the current detecting means. The method of claim 1, The comparison amplification means includes a plurality of comparison amplifiers; And a switching unit configured to select an output of each of the comparative amplifiers and apply the selected outputs to the blocking detection means.