KR101813673B1 - Short current reduction apparatus, and circuit breaker, cabinet panel and cable reel apparatus using thereof - Google Patents

Abstract

A short-circuit current reducing apparatus according to the present invention includes: a first input terminal and a second input terminal connected to a power system network and to which an AC power is applied; A first output terminal and a second output terminal connected to the load side; A first forward winding wound in a positive direction with a winding number of N1p and a first reverse winding wound in a reverse direction with a winding number of N1n so as to generate a magnetic flux in a first direction by a first current input from the first input terminal Input winding portion (where 0 < N1n <N1p); A second reverse winding magnetically coupled to the input winding section and wound in the reverse direction with the number of turns of N2n to generate a magnetic flux in a second direction opposite to the magnetic flux in the first direction by the first current, An output winding portion (here, 0? N2p &lt; N2n) including a second forward winding wound in a forward direction with the number of turns of N2p; N1p, N1n, N2n, and N2p are connected to the first and second output terminals of the output winding section, and N1p, N1n, N2n and N2p are expressed by the following equations: N1p-N1n> (R, S, T phase) of the power system, it is possible to reduce the short-circuit current and thereby reduce the spark and overheating due to the short circuit, It is effective to prevent a second accident caused by a fire, a fire or a power failure when a short circuit occurs in the power system.

Description

TECHNICAL FIELD [0001] The present invention relates to a short-circuit current reducing apparatus and a circuit breaker, a distribution board, and a cable reel apparatus using the same,

The present invention relates to an apparatus for reducing a short-circuit current in a power system, and more particularly, to a system and method for reducing a short-circuit current when a short circuit occurs in a single-phase or three-phase (R, S, T phase) Thereby preventing overheating of spark and electric wire caused by a short circuit and preventing short-circuiting of short-circuit point to prevent electric shock from spreading. Thus, it is possible to prevent a secondary accident caused by fire, To a short-circuit current reducing apparatus.

Generally, in the power system, the 22.9 kv-y power distribution system supplies power directly from a substation to a large-scale customer such as a factory or a building through a 3-phase 4-wire distribution line, or through a secondary transformer to a small- To the power supply. Such distribution lines are constructed in the form of machined lines in the outskirts of cities and farming and fishing villages, but they are buried underground in areas where beauty is important, such as large cities and amusement parks.

The three-phase four-wire distribution system will provide power by combining the neutral (N) and power lines (R, S, and T phases) by Y wire, delta wire or wieder wire. Here, when one power line and another power line are connected to each other, 380V is obtained. When one power line (for example, R phase) and a neutral line (N) are connected, 220V is provided to supply power to the load.

If a short circuit occurs, unbalanced power is generated on the load side as well as life and fire accidents due to overheating of the spark and the electric wire, and the loads such as the refrigerator and the washing machine connected to the three-phase line are burned.

This will be described in more detail as follows.

The power system is managed through various relay devices in a step-by-step manner for stable use of electricity from electrical failures such as short circuits.

The relay senses the input voltage and current and detects the current / overvoltage / phase / reverse / ground fault current and activates the circuit breaker (CB) so that the power network operates independently, , Or the failure of the electric power company side is prevented from propagating to the private car side, thereby making the whole system network operate stably.

The most representative function of these relays is to detect and block overcurrent and ground fault.

Generally, since the overcurrent is present in the load, it is necessary to shut off the load by detecting the abnormal current on the load side. Here, the relay operation by the overcurrent must be performed in an individual operation, and only the upper relay in which the overcurrent occurs should be operated. If the generated overcurrent is a large current that can operate up to the top relay (electric company relay), the top relay will also be cut off by the overcurrent operation. In this case, a large power outage occurs .

Therefore, in order to suppress such an operation, the overcurrent relay has various operating conditions such as a predetermined time / inverse time / early time, and the operation time is variablely operated according to the magnitude of the overcurrent. In other words, the operation time of the lower overcurrent relay is set to be faster than the operation time of the upper overcurrent relay, so that the overcurrent generating load can be separated from the system in a short period of time, so that the entire system can be stably operated.

However, in the case of a short-circuit accident, the breaker does not operate according to the length or thickness of the load-side electric wire using the breaker capacity and electricity under the electric usage condition of the general customer, so electric fires due to overheating of the electric wire are frequent, Even if instantaneous sparks and overcurrents are caused, life and property damage are constantly occurring every year.

In addition, when the overcurrent relay operates due to a short circuit, the main breaker and the load side breaker are simultaneously shut off, or the transformer fuse of the KEPCO is also cut off, resulting in a secondary damage caused by a power failure It takes a considerable amount of time to restore it to normal.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in order to solve the problems of the prior art, and it is an object of the present invention to reduce a short circuit current in a single phase or three phases (R, S, T phases) of a power system, A short circuit current reducing device capable of preventing a secondary accident caused by a fire, a fire, or a power outage when a short circuit occurs in the power system by preventing short-circuiting of the power system by preventing short- It is an object of the present invention to provide a blocking device, a distribution board, and a cable reel device.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise forms disclosed. Other objects, which will be apparent to those skilled in the art, It will be possible.

According to an aspect of the present invention, there is provided a short-circuit current reducing apparatus comprising: a first input terminal and a second input terminal connected to a power system network and to which an AC power is applied; A first output terminal and a second output terminal connected to the load side; A first forward winding wound in a positive direction with a winding number of N1p and a first reverse winding wound in a reverse direction with a winding number of N1n so as to generate a magnetic flux in a first direction by a first current input from the first input terminal Input winding portion (where 0 < N1n <N1p); A second reverse winding magnetically coupled to the input winding section and wound in the reverse direction with the number of turns of N2n to generate a magnetic flux in a second direction opposite to the magnetic flux in the first direction by the first current, An output winding portion (here, 0? N2p &lt; N2n) including a second forward winding wound in a forward direction with the number of turns of N2p; N1p, N1n, N2n, and N2p are connected to the first and second output terminals of the output winding section, and N1p, N1n, N2n and N2p are expressed by the following equations: N1p-N1n> -N2p). &Lt; / RTI &gt;

According to an embodiment of the present invention, there is provided a short-circuit current reducing apparatus comprising: at least one output winding section; And at least one output terminal coupled to the at least one output winding section, and wherein the at least one output winding section and the remaining windings satisfy the above equation.

In the short-circuit current reducing device according to an embodiment of the present invention, the short-circuit currents at the first and second output stages are adjusted to an equivalent impedance seen at both ends of the output winding section, It is desirable to set the position, the resistance of the winding, the shape of the magnetic core, or the gap on the magnetic core using at least one or more.

In the short-circuit current reducing device according to an embodiment of the present invention, the output winding section may further include an impedance section connected in series to the second forward winding or the second reverse winding separately from the equivalent impedance, It is preferable to include at least one inductor.

According to an embodiment of the present invention, there is provided a short-circuit current reducing apparatus comprising: at least one variable tab provided at a periphery of one end of both ends of the output winding section corresponding to the first and second output ends; And a tap switching portion for selectively connecting one end of the output winding portion or one end of the first and second output ends to the one or more variable taps.

In the short-circuit current reducing device according to an embodiment of the present invention, it is preferable that the tab switching portion is manually operated.

The short-circuit current reducing apparatus according to an embodiment of the present invention may further include an output voltage sensing unit for sensing a voltage between both ends of the first and second output terminals, And one end of the second output terminal is selectively connected to one end or both ends of the output winding portion or the at least one variable tap.

In the short-circuit current reducing device according to the embodiment of the present invention, the number of turns N1n of the first reverse winding of the input winding portion and the number of turns N2p of the second forward winding of the output winding portion are zero, The number of turns N1p is preferably twice the number of turns N2n of the second reverse winding of the output winding section.

It is preferable that one end of the output winding section is connected to the first input terminal or the second input terminal in the short-circuit current reducing apparatus according to an embodiment of the present invention.

The short-circuit current reducing device according to an embodiment of the present invention includes a plurality of cascade-connected transformers, and at least one of the plurality of transformers is preferably the short-circuit current reducing device.

According to another aspect of the present invention, there is provided a short-circuit current reducing / breaking device including: a short-circuit current reducing device; An abnormal state sensing unit connected to the short-circuit current reducing device to sense an abnormal state of the load side; And a switch unit for disconnecting the load from the AC power source when it is determined that a short circuit or an overcurrent occurs in the load in accordance with the detection result of the abnormal state sensing unit.

In the short-circuit current reduction device according to the second embodiment of the present invention, it is preferable that the abnormal state sensing unit senses a current flowing in the first input terminal, the second input terminal, or the first and second output terminals.

In the short-circuit current reduction device according to the second embodiment of the present invention, the abnormal state sensing unit senses a voltage between two nodes in the short-circuit current reduction device, And in the abnormal state, it is preferable to exceed the reference voltage.

The short-circuit current reduction blocking device according to the second embodiment of the present invention is characterized in that one of the two nodes is a node drawn out from the output winding section and the other of the two nodes is a node drawn out from the input winding section Do.

In the short-circuit current reduction device according to the second embodiment of the present invention, the abnormal state sensing unit senses a voltage between two nodes in the short-circuit current reduction device, and the magnitude of the voltage between the two nodes is a reference voltage And in the abnormal state, it is preferable to be equal to or lower than the reference voltage.

In the short-circuit current reduction device according to the second embodiment of the present invention, it is preferable that the two nodes are nodes drawn out from the input winding section.

The short-circuit current reduction device according to the second embodiment of the present invention is characterized in that the switch section is one or a combination of a semiconductor switch, a circuit breaker, a magnetic switch or a relay, It is preferable that at least one is provided between the current reducing apparatus and the load.

The short-circuit current reduction device according to the second embodiment of the present invention may further include an alarm generator for generating an alarm when it is determined that short-circuit or over-current has occurred in the load in accordance with the detection result of the abnormal- Is preferably an audible or visual alarm.

In order to achieve the above object, a three-phase short-circuit current reducing apparatus according to a third embodiment of the present invention includes an R input terminal, an S input terminal and a T input terminal receiving three-phase power from a power grid network; An R output terminal connected to the load, an S output terminal and a T output terminal; And a short-circuit current reducing device connected between each of the input terminals and the neutral point, wherein a first input terminal of each of the short-circuit current reducing devices is respectively connected to the R input terminal, the S input terminal, and the T input terminal, Each of the first input terminal and the second output terminal is commonly connected to the neutral point, and the other one of the first and second output terminals of the short-circuit current reducing device is connected to the R output terminal, the S output terminal, and the T output terminal Respectively.

It is preferable that the three-phase short-circuit current reducing device according to the third embodiment of the present invention be integrally formed.

Preferably, the three-phase short-circuit current reducing device according to the third embodiment of the present invention further includes at least one transformer connected in cascade with the short-circuit current reducing device.

In the three-phase short-circuit current reducing apparatus according to the third embodiment of the present invention, it is preferable that at least one of the at least one transformer is the short-circuit current reducing apparatus.

In order to achieve the above object, a distribution board according to a fourth embodiment of the present invention is a distribution board including a main breaker and a branch circuit breaker, and branching the supplied AC power to the load, Wherein the short-circuit current reducing device is characterized in that it is the short-circuit current reducing device described above.

Preferably, the distribution board according to the fourth embodiment of the present invention further includes at least one transformer connected in cascade with the short-circuit current abatement device.

In the distribution board according to the fourth embodiment of the present invention, it is preferable that at least one of the at least one transformer is the short-circuit current reduction device.

The distribution board according to the fourth embodiment of the present invention may further include an abnormal state sensing unit connected to the shortcurrent reduction apparatus and sensing an abnormal state of the load, It is preferable that at least one of the main breaker and the branch breaker is shut off when it is determined that an overcurrent has occurred.

In the distribution board according to the fourth embodiment of the present invention, it is preferable that the abnormal state sensing unit senses a current flowing in the first input terminal, the second input terminal, or the first and second output terminals.

In the distribution board according to the fourth embodiment of the present invention, the abnormal state sensing unit senses a voltage between two nodes in the shortcircuit reduction apparatus, the magnitude of the voltage between the two nodes is less than a reference voltage in a steady state, It is preferable to exceed the reference voltage.

In the distribution board according to the fourth embodiment of the present invention, it is preferable that one of the two nodes is a node drawn out from the output winding section, and the other of the two nodes is a node drawn out from the input winding section.

In the distribution board according to the fourth embodiment of the present invention, the abnormal state sensing unit senses a voltage between two nodes in the short-circuit current reduction device, the magnitude of the voltage between the two nodes exceeds a reference voltage in a steady state, It is preferable that the voltage is equal to or lower than the reference voltage.

In the distribution board according to the fourth embodiment of the present invention, it is preferable that the two nodes are nodes drawn out from the input winding section.

The distribution board according to the fourth embodiment of the present invention further includes an alarm generating unit for generating an alarm when it is determined that a short circuit or an overcurrent occurs in the load in accordance with the detection result of the abnormal state sensing unit, It is preferable to be a visual alarm.

In order to achieve the above object, a cable reel apparatus according to a fifth embodiment of the present invention includes a cable reel unit wound around a cable, and a receptacle provided to electrically connect the cable and the load unit, And a short-circuit current reduction unit connected between the cable and a socket to reduce a short-circuit current on the load side, wherein the short-circuit current reduction unit is a short-circuit current reduction unit.

In order to achieve the above object, a cable reel apparatus according to a fifth embodiment of the present invention includes a cable reel unit wound around a cable, and a receptacle provided to electrically connect the cable and the load unit, And a short-circuit current reduction unit connected between the cable and a socket to reduce a short-circuit current on the load side, wherein the short-circuit current reduction unit is a short-circuit current reduction shut-off unit.

The short-circuit current reducing device according to the present invention and the breaking device, the distribution board and the cable reel device using the same reduce the short-circuit current when a short circuit occurs in a single-phase or three-phase (R, S, T phase) It not only reduces spark and wire overheating due to short circuit but also prevents sudden spread of power by rapidly blocking short circuit point. It is an excellent effect to prevent secondary accident caused by fire, accident or power outage in the power system. have.

1 is a block diagram of a power system to which a short-circuit current reduction device according to the present invention is applied.
2 is an internal circuit diagram of a short-circuit current reducing device according to the present invention.
Fig. 3 and Fig. 4 are views showing a modification of the short-circuit current reducing device of Fig. 2;
Fig. 5 is an equivalent circuit diagram in which the short-circuit current reducing device of Fig. 2 is simplified. Fig.
Fig. 6 is a circuit diagram in which the internal equivalent impedance of a winding is taken into consideration in the short-circuit current reducing device of Fig. 5;
7 (a) and 7 (b) are explanatory views for explaining the operation of the short-circuit current reducing device of FIG. 6; Fig. 7 (a) shows the case of normal operation, and Fig. 7 (b) shows the case where the load is short-circuited.
Fig. 8 is an exemplary view showing application of a variable tap and a tab switching portion to the short-circuit current reducing device of Fig. 5; Fig.
9 (a) and 9 (b) are block diagrams showing a case where the short-circuit current reducing apparatus of the present invention is applied as a cascade.
10 is a block diagram showing a short-circuit current reduction interrupter according to the present invention.
Fig. 11 is an exemplary diagram showing a case where both ends of a winding are extracted in the short-circuit current reduction device of Fig. 10; Fig.
Fig. 12 (a) and Fig. 12 (b) are waveform diagrams showing the change of both end voltages in Fig. 11 during normal or short-circuit operation on the load side.
13 is a circuit diagram showing a three-phase short-circuit current reducing device according to the present invention.
14 is a block diagram showing a distribution board according to the present invention.
15 is a block diagram showing a switchboard according to the present invention;
16 is a block diagram showing an electric motor control board according to the present invention.
17 is a perspective view of a cable reel apparatus according to the present invention.
FIG. 18 is a partial cross-sectional view showing the interior of the cable reel apparatus of FIG. 17;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following detailed description is merely exemplary and is merely illustrative of preferred embodiments of the present invention.

1 is a block diagram showing a case where the short-circuit current reducing apparatus 100 according to the present invention is applied on a power system.

Referring to FIG. 1, a short-circuit current reducing apparatus 100 according to the present invention receives an AC power source 10 and transfers the AC power source 10 to a load 20. Here, the load 20 is not limited to an individual electric device but should be considered to include all the electric devices installed on the load 20 side. The shortcircuit current reducing apparatus 100 disposed between the AC power source 10 and the load 20 operates to reduce the short circuit current when a short circuit occurs on the load 20 side. The detailed configuration and operation of the short-circuit current abatement apparatus 100 will be described later with reference to the drawings.

Fig. 2 is an internal circuit diagram showing a general configuration of the short-circuit current abatement apparatus 100 according to the present invention.

2, the short-circuit current abatement apparatus 100 of the present invention includes a first input terminal 131 and a second input terminal 132 to which an AC power source 10 is applied, And a first output terminal 141 and a second output terminal 142 connected to the first input terminal 131 and the second input terminal 132. The first input terminal 131 and the second output terminal 142 are connected in series between the first input terminal 131 and the second input terminal 132, (110) for generating a magnetic flux in a second direction which is magnetically coupled to the input winding section (110) and is opposite in direction to the magnetic flux in the first direction by the first current, the input winding section The output winding section 120 is connected in series.

The input winding section 110 may be constituted only by the first forward winding 111 wound in the forward direction with the number of turns of N1p so as to generate the magnetic flux in the first direction by the first current, And a first reverse winding 112 wound with a winding number of N1n in a direction opposite to the first forward winding 111 so as to generate a magnetic flux in a second direction, In this case, since the magnetic fluxes in the first direction and the magnetic fluxes in the second direction are canceled by the input winding section 110 and only the magnetic fluxes in the first direction are to be left, the number of turns N1n of the first reverse winding 112 is, Lt; RTI ID = 0.0 &gt; N1p. &Lt; / RTI &gt; Therefore, the number of turns N1n of the first reverse winding 112 has a range satisfying 0? N1n &lt; N1p.

The output winding section 120 is constituted only by the second reverse winding 122 wound in the reverse direction with the number of turns of N2n so as to generate the magnetic flux in the second direction opposite to the magnetic flux in the first direction by the first current And a second forward winding 122 wound in a forward direction with a winding number of N2p in a direction opposite to the winding 122 of the second second reverse winding 122 so as to generate a magnetic flux in a first direction opposite to the second direction 121). In this case, since the magnetic fluxes in the second direction and the magnetic fluxes in the first direction are canceled by the output winding section 120 and only the magnetic fluxes in the second direction must be left, the number N2p of windings of the second forward winding 121 is set to the second reverse winding 122, Lt; 2 &gt; Therefore, the number of turns N2p of the second forward winding 121 has a range satisfying 0? N2p &lt; N2n.

The input AC voltage Vac applied to the first and second input stages 131 and 132 is distributed to the input winding unit 110 and the output winding unit 120 in the normal operation state and is supplied to the output winding unit 120 in this case The secondary voltage V2 is given by Equation 1 below.

Since the denominator of Equation (1) can not be zero, Equation (1) is valid under the condition of N1p-N1n? N2n-N2p.

An input AC voltage Vac applied to the first and second input stages 131 and 132 is applied to the input winding part (or the output winding part) when a short circuit occurs between the first and second output terminals 141 and 142 drawn out from the output winding part 120 110, the secondary voltage V2.sh induced in the output winding section 120 at the time of short-circuiting can be obtained by the following equation (2).

If the relationship between the number of turns of the windings is set appropriately, the secondary voltage V2.sh induced in the output winding section 120 at the time of short-circuit is more than the secondary voltage V2 induced in the output winding section 120 during normal operation The effect of reducing the short-circuit current on the load side can be obtained.

If the secondary voltage V2.sh at the time of short-circuiting is set smaller than the secondary voltage V2 at the time of normal operation by using Equations (1) and (2), the relationship of the number of turns as shown in Equation (3) below can be obtained.

As described above, the equation (3) is also valid under the condition of N1p-N1n? N2n-N2p.

In other words, when the number of turns of the input winding section 110 and the output winding section 120 in the short-circuit current reducing apparatus 100 of the present invention shown in FIG. 2 satisfies the expression (3) , The secondary voltage V2.sh of the output winding section 120 decreases, and the short-circuit current also decreases in proportion thereto. Also, as described above, it is easily understood by a person skilled in the art that the above Equation 3 is also valid under the condition that N1p-N1n is not equal to N2n-N2p.

The short-circuit current reducing apparatus 100 according to the present invention is not limited to the structure shown in Fig. 2, and may be constructed by arranging a plurality of windings of the input winding section 110 or the output winding section 120 and deforming them into various forms It is possible. 3 and 4 illustrate a modification using the short-circuit current reducing device 100 of the present invention.

Fig. 3 shows an example in which the output winding section 120 and the output stage are arranged in plural in the short-circuit current reducing device 100 of Fig. 2, and Fig. 4 shows an example in which the output winding section 120 is arranged in the input winding section 110 As shown in FIG.

3 is composed of one input winding 110 and two output windings 120. Each output winding 120 is connected to a second forward and reverse windings 121, 122, and third forward and reverse windings 123, 124, respectively. Even when there are a plurality of output winding sections 120, if the relationship of the expression (3) is satisfied between the windings except for the output winding section 120 and the output winding section 120, An effect that the short-circuit current is reduced for one output terminal can be obtained. Although the short-circuit current abatement apparatus 100 shown in FIG. 3 exemplifies a case where there are two output winding sections 120, it is apparent to a person skilled in the art that a configuration including the output winding section 120 furthermore is also possible.

4, the second output terminal 142 is not connected to the second input terminal 132, and the output winding section 120 is connected between the input winding section 110 As shown in FIG. 4, the short-circuit current reducing device 100 divides the input winding portion 110 into a plurality of input windings 110, and the first and second windings 111 and 112 and the fourth forward direction And reverse windings (113, 114). Even in this case, if the expression (3) is satisfied between the windings of the output winding section 120 and the input winding section 110, the short-circuit current can be reduced at the time of short-circuit. In this case, N1p in Equation 3 is equal to the sum (N11p + N12p) of the number of turns of the first forward winding 111 and the fourth forward winding 113, and N1n in Equation 3 is the sum of the number of turns of the first reverse winding 112 Is equal to the sum (N11n + N12n) of the number of turns of the fourth reverse winding 114.

Fig. 5 shows a circuit in which the short-circuit current abatement apparatus 100 of Fig. 2 is simplified.

The input winding unit 110 of FIG. 2 includes the first forward winding 111 and the first reverse winding 112 wound at a smaller winding number than the first forward winding 111. However, the input winding unit 110 includes the first forward winding 111, The magnetic flux in the second direction by the first reverse winding 112 is canceled and only the magnetic flux in the first direction is left. In this case, the input winding portion 110 of FIG. (= N1p-N1n) obtained by subtracting the number of turns N1n of one reverse winding 112 from the number of turns of the reverse winding 112 and is wound in the forward direction.

2 is composed of the second reverse winding 122 and the second forward winding 121 wound at a smaller winding number than that of the second reverse winding 122 and the second reverse winding 122 of the second reverse winding 122, The magnetic flux in the first direction by the second forward winding 121 in the magnetic flux is canceled and only the magnetic flux in the second direction is left. In this case, the output winding section 120 of FIG. 2 is wound in the winding number N2n of the second reverse winding 122 Is equivalent to a winding wound in the reverse direction with the number of turns of N2 (= N2n-N2p) minus the number of turns N2p of the second forward winding 121. [

Therefore, the short-circuit current abatement apparatus 100 shown in Fig. 5 is a circuit equivalent to that shown in Fig. From Equation (1) and Equation (2) can be rewritten from the configuration of FIG.

As described above, the equation (4) is also valid under the condition that N1? N2.

3, the short-circuit current reducing apparatus 100 shown in FIG. 5 must satisfy the following condition (5): &quot; (5) &quot;

As described above, the equation (5) is valid under the condition that N1? N2.

In order to examine the practical operation of the short-circuit current reducing apparatus 100 shown in FIG. 5, an equivalent impedance Zt viewed from the output winding unit 120 is considered in FIG. Since the short-circuit current reducing apparatus 100 of the present invention is configured in the form of a single-phase transformer, the equivalent impedance Zt is an impedance that equivalently takes into consideration leakage inductance, iron loss, and copper loss of the single phase transformer viewed from the output winding section 120. The equivalent impedance can be adjusted by using at least one of the arrangement of the input winding portion 110 and the output winding portion 120, the resistance of the winding, the shape of the magnetic core, or the gap on the magnetic core

7 (a) and 7 (b) show voltage and current when the short-circuit current abatement apparatus 100 of Fig. 6 operates normally and when the load is short-circuited.

7 (a) shows the voltage and current when the normal load impedance Zo is connected to the first and second output terminals 141 and 142 of the short-circuit current abatement device 100. The voltage V2 and the output current Io induced in the output winding 120 corresponding to the input AC voltage Vac and the input current I1 are obtained by a circuit analysis technique as shown in Equation 6 below.

Here, n is given by n = N1 / N2 as a ratio of the input winding section 110 to the output winding section 120. [

7B shows voltage and current when a short circuit occurs in a load connected to the first output terminal 141 and the second output terminal 142 of the shortcircuit current reducing apparatus 100. [ The voltage V2.sh and the short-circuit current Ish induced in the output winding section 120 at the time of short-circuit can be obtained by substituting 0 ohm into the load impedance Zo by using Equation (6), as shown in Equation (7).

As can be seen from Equation (7), the short-circuit current Ish can be adjusted by the equivalent impedance Zt of the output winding portion 120 side in addition to the winding ratio n. In other words, by increasing the equivalent impedance Zt, the short-circuit current Ish can be reduced. The equivalent impedance Zt is determined by considering the leakage inductance, iron loss, and copper loss of the single phase transformer viewed from the output winding section 120 as described above, and the arrangement of the input winding section 110 and the output winding section 120, The shape of the magnetic core, or the gap on the magnetic core. Although not shown in FIG. 6, an impedance unit coupled in series with the equivalent impedance Zt may further be added to further reduce the short-circuit current Ish at the time of short-circuit. The impedance unit may include a resistor or an inductor.

Referring to Equation (6) and Equation (7), when the winding ratio n of the input winding portion 110 to the output winding portion 120 is set to 2, the output winding portion 120 The induced voltage V2 of the output winding section 120 and the output current Io of the output winding section 120 are given by V2 ?? Vac and Io ?? Vac / Zo (? Zo ??? Zt) V2.sh and short-circuit current Ish are given by V2.sh = Vac / 2, Ish = Vac / (4Zt). In other words, when applying the short-circuit current reducing device 100 according to the present invention by setting the winding ratio n = 2 between the input winding section 110 and the output winding section 120, the output winding section 120 V2 = V2.sh = Vac / 2 in the output winding section 120 is reduced to 1/2 of that in the normal load when the load is short-circuited because the induced voltage V2 of the input voltage V2 is equal to the input voltage, It can be seen that the short-circuit current is also reduced.

The short circuit current reducing apparatus 100 according to the present invention adjusts the winding ratio n of the input winding unit 110 and the output winding unit 120 so that the induced voltage V2 of the output winding unit 120 is reduced Or boosted. The winding ratio n can be variously adjusted. However, as can be seen from Equations (6) and (7), when the winding ratio n is set to 2, the output winding portion 120 having the same magnitude as the input voltage Vac at the normal load condition The voltage V2 and the output voltage Vo can be obtained. Under the condition that the load 20 is short-circuited, it can be seen that the short circuit current is reduced because the induced voltage V2 of the output winding section 120 is lower than the normal load condition

FIG. 8 shows an embodiment in which the variable taps 160 and the tapped ring portions 150 are applied to the short-circuit current reducing device 100 of FIG.

When the load impedance Zo becomes smaller, the output voltage Vo becomes smaller due to the law of voltage distribution between the equivalent impedance Zt and the load impedance Zo. Therefore, in order to compensate the above, the short-circuit current abatement apparatus 100 according to the present invention, And a variable tap 160 that can adjust the turns ratio of the input winding unit 110 and the output winding unit 120. [ One of the variable tabs 160 is selectively connected to the first output end 141 by the tangential ring portion 150. The tactile feedback unit 150 may be manually operated by the user, but it may further include an output voltage sensing unit 170, as shown in FIG. 8, to compensate for a variation of the output voltage by more than a predetermined level. The tactile feedback unit 150 can be controlled according to the detection result of the tactile feedback unit 170.

Figures 9 (a) and 9 (b) show a configuration in which the short-circuit current abatement device 100 is cascade-connected to the transformer 180. [

9A, the short-circuit current abatement apparatus 100 according to the present invention can be cascade-connected to a general transformer 180, and can be connected to the short-circuit current abatement apparatus 100 as shown in FIG. 9 (b) Multiple cascade connections are possible. Thus, the input / output voltage ratio can be appropriately set and the short circuit current can be further reduced.

10 shows a short-circuit current reduction device 200 using the short-circuit current reduction device 100 according to the present invention. The short-circuit current reducing apparatus 100 according to the present invention reduces the short-circuit current when a short circuit occurs on the side of the load 20 to reduce overheating of sparks and electric wires caused by a short circuit, It may be implemented as the short-circuit current reducing and breaking device 200 as shown in FIG. 10 in order to further secure safety.

10, the short-circuit current reducing and breaking apparatus 200 according to the present invention includes a short-circuit current reducing apparatus 100 and a short-circuit current reducing apparatus 100 connected to the short-circuit current reducing apparatus 100, An AC power source 10 for supplying the AC power to the load 20 in response to a detection result of the abnormal state sensing unit 210; (Not shown). The short-circuit current reducing and breaking device 200 further includes an alarm generating unit 230 for generating an alarm when it is determined that a short circuit or an over-current occurs in the load 20 according to the detection result of the abnormal state detecting unit 210 And the alarm may be an audible or visual alarm.

10 shows a configuration in which the abnormal state sensing unit 210 senses a current flowing through the first input terminal 131 and the second input terminal 132 or senses a current flowing through the first and second output terminals 141 and 142 As shown in FIG. 11, the abnormal state sensing unit 210 may sense a voltage between two nodes in the short-circuit current reducing apparatus 100 to determine whether the voltage is short-circuited or over-current.

The short-circuit current reducing apparatus 100 shown in Fig. 11 is for the case where the turns ratio of the input winding section 110 and the output winding section 120 is 2. For example, the nodes A, B and C are shown in Fig. 11 12 (a) and 12 (b) show how the voltage between the AC node and the AB node changes under the normal load condition and the short-circuiting condition, respectively. In the case where the abnormal state sensing unit 210 senses the voltage across the AC node and sets the reference voltage between 0 V and Vac / 2, the voltage between the AC nodes is less than the reference voltage in the steady state, In the abnormal state, such as a short circuit or an overcurrent, the reference voltage is exceeded, so that the switch unit 220 can be cut off by determining whether a short circuit or an overcurrent occurs. When the abnormal state sensing unit 210 senses the voltage across the AB node and sets the reference voltage between Vac / 2 and Vac, the magnitude of the voltage between the AB nodes exceeds the reference voltage in the steady state, The switching unit 220 may be disconnected by determining whether a short circuit or an overcurrent occurs by using the reference voltage. It is possible to easily determine whether a short-circuit or an over-current occurs by setting various nodes in addition to the node illustrated in FIG. 11 and using the both-end voltages between the nodes through a simple design change.

The switching unit 220 included in the short-circuit current cut-off device 200 according to the present invention is a component that opens and closes a circuit by a control signal from the abnormal state detection unit 210. The switching unit 220 includes a semiconductor switch, Or a combination thereof, and at least one of them may be installed between the power system and the short-circuit current abatement device 100, or between the short-circuit current abatement device 100 and the load 20 Do.

In the above description, the short-circuit current reducing apparatus 100 according to the present invention is applied to a single-phase AC power source. However, the present invention can be applied to a three-phase four- ) And a power line (R phase, S phase, T phase). The configuration for this is shown in Fig.

13, the three-phase short-circuit current reducing device 300 according to the present invention includes three single-phase short-circuit current reducing devices 100, and each of the short- The first input terminal 131 is connected to the R input terminal R1, the S input terminal S1 and the T input terminal T1 to which the three-phase power is applied and the second input terminal 132 of each of the short- One of the first and second output terminals 141 and 142 is commonly connected to the neutral point N and the other of the first and second output terminals 141 and 142 of each of the shortcircuit reduction devices 100 is connected to the R output terminal R2, an S output terminal S2, and a T output terminal T2, respectively, to output three-phase power to the load side.

The short-circuit current reducing device 300 for three phases according to the present invention can reduce the short-circuit current in response to a short circuit between the output terminals R2, S2, and T2 of the respective phases and a neutral point or a short circuit between the phases. In addition, the three-phase short-circuit current reducing device 300 of the present invention can be constructed by connecting the individual short-circuit current reducing devices 100, or can be integrally formed in a single enclosure. Also, the three-phase short-circuit current reducing device 300 according to the present invention can further cascade the general transformer 180 or the short-circuit current reducing device 100 of the present invention as described above.

Fig. 14 shows an embodiment in which the distribution board 400 is implemented using the short-circuit current reducing apparatus 100 of the present invention.

A typical distribution board is an apparatus that serves as an entrance to a converter that distributes power supplied from the outside in accordance with the capacity of the load in an industrial facility circuit and an outside circuit inside a building. The circuit board circuit breaker such as a wiring breaker and an earth leakage breaker Is installed to cut off the branch circuit from the main bus line in case of an over current or short circuit to prevent electric accident. However, in the conventional distribution panel, a short circuit current is formed when a short circuit occurs on the load side due to the limitation of the breaking speed of a circuit breaker or the like, so that the fire caused by spark or electric wire overheating can not be effectively prevented, There has been a problem of spreading.

14, the distribution board 400 according to the present invention includes a main breaker 410 and a branch breaker 420. The main breaker 410 and the branch breaker 420 are connected to each other, And a short-circuit current reducing device 100 according to the present invention for reducing the short-circuit current on the side of the load 20 between the first and second switches. The distribution board 400 according to the present invention further includes an abnormal state sensing unit 210 similar to the shortcurrent reducing and breaking device 200 shown in FIGS. 10 and 11, And disconnects at least one of the main breaker 410 and the branch breaker 420 when it is determined that a short circuit or an overcurrent occurs in the load 20 according to the detection result. In addition, the distribution board 400 according to the present invention may further include an alarm generating unit 230 generating an audible or visual alarm when it is determined that a short circuit or an overcurrent occurs in the load 20.

The distribution board 400 of the present invention shown in Fig. 14 can be constructed by further cascading one or more conventional transformers 180 or short-circuit current abatement devices 100 to the short-circuit current abatement device 100 have. Since the combining method has been described with reference to FIGS. 9 (a) and 9 (b), a detailed description thereof will be omitted here.

Further, the short-circuit current abatement apparatus 100 according to the present invention can be applied to a switchboard 500 installed in a power supply, and an exemplary embodiment thereof is shown in Fig.

Generally, switchgear is used in a wide range of power consumers, such as residential areas (eg apartments), buildings, schools, factories, ports, airports, water and sewage treatment plants, substations, heavy industrial plants, subways, It is installed in a water distribution system that converts power to low pressure and supplies it to premises equipment. It is used for power monitoring, control and protection.

15, the switchboard 500 according to the present invention includes a high-voltage main breaker 510 and a low-voltage main breaker 530, and a transformer unit 520 for transforming the drawn-in electricity, (520) includes a short-circuit current reducing section for reducing the short-circuit current. The short-circuit current reducing section includes the short-circuit current reducing apparatus (100) of the present invention. The short-circuit current abatement apparatus 100 included in the switchboard 500 according to the present invention includes the same technical features of the short-circuit current abatement apparatus 100 described above. A power distributor 540 including a plurality of wiring breakers 550 is disposed at a rear end of the transformer unit 520 to distribute and supply electric power to the load 20 side.

The transformer unit 520 included in the switchboard 500 according to the present invention may further include a transformer connected in cascade with the short-circuit current reducing apparatus 100, and the transformer may be a three-phase transformer 521. In this case, the short-circuit current reducing apparatus 100 may be a three-phase short-circuit current reducing apparatus 300 according to the present invention.

The switchboard 500 according to the present invention further includes an abnormal state sensing unit 210 connected to the short-circuit current reducing apparatus 100 or the three-phase short-circuit current reducing apparatus 300 to detect an abnormal state on the load side . If it is determined that a short circuit or an overcurrent occurs in the load according to the detection result of the abnormal state sensing unit 210, the high voltage main breaker 510, the low voltage main breaker 530, or the power distributing unit 540 shown in FIG. 15 And opens the included wiring breaker 550 to cut off three-phase or single-phase power. The abnormal state sensing unit 210 senses a current flowing through the input or output terminal of the short-circuit current reducing apparatus 100 or the three-phase short-circuit current reducing apparatus 300, or detects the current flowing through the short-circuit current reducing apparatus 100 or the three- Detects a voltage between any node in the input winding unit 110 or the output winding unit 120 of the transformer 300 and judges whether the load is short-circuited or over-current. The details of this have already been described above, so the description thereof is omitted here.

16 shows an electric motor control panel 600 to which the short-circuit current reducing apparatus 100 according to the present invention is applied.

The electric motor control panel is a collection of medium and large starters and protective devices, and it should be able to function as a rational and systematic power distribution device as an electric device that systematically constructs the power supply in the building. In order to prevent this, thorough maintenance is necessary.

Such a conventional motor control panel and automatic control panel can be used for indoor fire hydrant main pump motor, indoor fire hydrant auxiliary pump, outdoor fire hydrant main pump, outdoor fire hydrant auxiliary pump, sprinkler main pump, sprinkler auxiliary pump, So that the power supply and the disconnecting operation are performed.

The electric motor control board 600 according to the present invention includes a short-circuit current reduction unit that includes a circuit breaker and a magnetic switch 630 and reduces a short-circuit current on the load side. The short- ). The circuit breaker of the motor control panel 600 according to the present invention may be a circuit breaker 550 and the shortcircuit reduction unit may include the three-phase shortcircuit reduction device 300 in place of the shortcircuit reduction device 100 have. The detailed configuration and operation of the short-circuit current reducing apparatus 100 or the three-phase short-circuit current reducing apparatus 300 included in the short-circuit current reducing unit are the same as those described above, and a detailed description will be omitted.

The motor control board 600 according to the present invention further includes an abnormal state sensing unit 210 connected to the short-circuit current reducing apparatus 100 or the three-phase short-circuit current reducing apparatus 300 to sense an abnormal state of the load , And may block at least one of the wiring breaker (550) and the magnetic switch (630) when it is determined that a short circuit or an overcurrent occurs in accordance with the detection result of the abnormal state sensing unit (210).

As shown in FIG. 16, the load of the motor control panel 600 is an electric motor 650, and the electric motor 650 includes a single-phase or a three-phase motor. When a short circuit occurs in the load, the short-circuit current reducing part reduces the short-circuit current to prevent an electric accident due to the short-circuit. If it is determined that a short circuit or an overcurrent is generated on the load side further including the abnormal state sensing unit 210, the abnormal state sensing unit 210 may block the wiring circuit breaker 550 of the main circuit, The magnetic switch 630 for supplying electric power to each electric motor 650 can be cut off through the control unit 610. [ In addition, the motor control board 600 according to the present invention may further include a fuse 620 for each branch circuit formed for each motor 650.

17 is a perspective view of a cable reel apparatus to which a short-circuit current abatement apparatus 100 and a short-circuit current abatement apparatus 200 according to the present invention are applied.

17, a cable reel apparatus according to the present invention includes a cylindrical cable winding portion 710 rotatably installed, a cable 740 such as a power line wound around the cable winding portion 710, And a fixing frame (not shown) for rotatably fixing the cable winding portion 710 away from the ground. A receptacle 720 is provided at one side of the body of the cable take-up part 710 for inserting a plug from the outside. A plug 730 capable of connecting to an outlet of an external power source is provided at an end of the cable 740 Respectively.

18 showing the inside of a cable reel apparatus according to the present invention, a cable reel apparatus according to the present invention includes a short-circuit current reducing unit connected between a cable 740 and a receptacle 720 to reduce a short- The short-circuit current reducing unit may be the short-circuit current reducing apparatus 100 of the present invention or the short-circuit current reducing and breaking apparatus 200 of the present invention.

The cable reel apparatus according to the present invention can be used in an environment where the use conditions are rougher and poorer than general rooms such as a construction site, a work site, an outdoor event site, and a camp site, and lives or fire frequently occurs due to a short-circuit accident. The cable reel apparatus according to the present invention reduces the short-circuit current in the short-circuit current reducing apparatus 100 when a short circuit occurs in the load, or short-circuits the current short- It has the effect of preventing damage or fire accident.

As described above, the short-circuit current abatement apparatus 100, the short-circuit current abatement apparatus 200, and the three-phase short circuit current abatement apparatus 300 according to the present invention can be applied to a single- or three- Phase), it is possible to reduce the short-circuit current and thereby reduce the spark and overheating due to the short circuit, as well as promptly shut off the short-circuit point so as to prevent the static electricity from spreading. , It is effective to prevent a secondary accident caused by a fire accident or a power failure.

Therefore, the short-circuit current reducing apparatus 100, the short-circuit current reducing and breaking apparatus 200, and the three-phase short-circuit current reducing apparatus 300 according to the present invention can be applied in various forms on the power system. For example, in a field where it is important to minimize damage from a short circuit accident such as an emergency induction lamp or an emergency outlet as a fire extinguisher as well as the distribution panel 400, the switchboard 500, the motor control panel 600, It will be understood by those of ordinary skill in the art that various modifications may be made.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

10: AC power supply 20: Load
100: short circuit current reducing device 110: input winding part
111, 112: first forward and reverse windings
113, 114: Fourth forward and reverse windings
120: Output winding section
121, 122: second forward and reverse windings
123, 124: 3rd forward and reverse windings
131, 132: first and second inputs
141 to 144: first to fourth output stages 150:
160: Variable tap 170: Output voltage sensing unit
180: Transformer 200: short-circuit current cutoff device
210: abnormal state detection unit 220:
230: alarm generator 300: three-phase short-circuit current reducing device
400: distribution board 410: main breaker
420: branch breaker 500: switchgear
510: high voltage main breaker 520: transformer part
521: Three-phase transformer 530: Low-voltage main breaker
540: Distribution part 550: Circuit breaker
600: Motor control board (MCC) 610: Operation control unit
620: Fuse 630: Magnetic switch
650: electric motor 710: cable winding part
720: Outlet 730: Plug
740: Cables, wires

Claims (34)

A first input terminal and a second input terminal connected to the power system network and to which the AC power is applied;
A first output terminal and a second output terminal connected to the load side;
A first forward winding wound in a positive direction with a winding number of N1p and a first reverse winding wound in a reverse direction with a winding number of N1n so as to generate a magnetic flux in a first direction by a first current input from the first input terminal Input winding portion (where 0 < N1n &lt;N1p);
A second reverse winding magnetically coupled to the input winding section and wound in the reverse direction with the number of turns of N2n to generate a magnetic flux in a second direction opposite to the magnetic flux in the first direction by the first current, An output winding portion (here, 0? N2p &lt; N2n) including a second forward winding wound in a forward direction with the number of turns of N2p;
N1p, N1n, N2n, and N2p are connected to the first and second output terminals of the output winding section, and N1p, N1n, N2n and N2p are expressed by the following equations: N1p-N1n> -N2p). &Lt; / RTI &gt;
The method according to claim 1,
At least one output winding section; And
Further comprising a pair of output terminals connected to the at least one output winding section,
And the above expression is satisfied for the at least one output winding section and the remaining windings.
The method according to claim 1,
The short-circuit currents of the first and second output terminals are adjusted to an equivalent impedance seen from both ends of the output winding section,
Wherein the equivalent impedance is set using at least one of an arrangement of the input winding portion and the output winding portion, a resistance of the winding, a shape of the magnetic core, or a gap on the magnetic core.
The method of claim 3,
The output winding section may further include an impedance section connected in series to the second forward winding or the second reverse winding separately from the equivalent impedance,
Wherein the impedance section includes at least one of a resistor and an inductor.
The method according to claim 1,
One or more variable tabs provided at the periphery of one end of both ends of the output winding portion corresponding to the first and second output ends; And
Further comprising a tap switching part for selectively connecting one end of either end of the output winding part or one end of the first and second output ends to the at least one variable tap.
6. The method of claim 5,
Wherein the tap switching unit is manually operated.
6. The method of claim 5,
And an output voltage sensing unit for sensing a voltage across the first and second output terminals,
Wherein the tap switching unit selectively connects one end of the first and second output terminals with one end of the output winding unit or one or more variable taps according to the detection result of the both end voltage.
The method according to claim 1,
The number of turns N1n of the first reverse winding of the input winding portion and the number of turns N2p of the second forward winding of the output winding portion are zero,
Wherein the number of turns N1p of the first forward winding of the input winding portion is twice the number of turns N2n of the second reverse winding of the output winding portion.
9. The method of claim 8,
And one end of the output winding section is connected to the first input terminal or the second input terminal.
A plurality of cascade-connected transformers,
Wherein at least one of the plurality of transformers is a short-circuit current reducing device according to any one of claims 1 to 9.
9. A circuit breaker according to any one of claims 1 to 9,
An abnormal state sensing unit connected to the short-circuit current reducing device to sense an abnormal state of the load side; And
And a switch for disconnecting the load from the AC power source when it is determined that a short circuit or an overcurrent occurs in the load in accordance with the detection result of the abnormal state sensing unit.
12. The method of claim 11,
Wherein the abnormal state sensing unit senses a current flowing in the first input terminal, the second input terminal, or the first and second output terminals.
12. The method of claim 11,
Wherein the abnormal state sensing unit senses a voltage between two nodes in the shortcircuit reduction apparatus, wherein a magnitude of a voltage between the two nodes is less than a reference voltage in a steady state and exceeds a reference voltage in an abnormal state. Abatement device.
14. The method of claim 13,
Wherein one of the two nodes is a node drawn out from the output winding section, and the other of the two nodes is a node drawn from the input winding section.
12. The method of claim 11,
Wherein the abnormal state sensing unit senses a voltage between two nodes in the shortcircuit reduction apparatus, wherein a magnitude of a voltage between the two nodes exceeds a reference voltage in a steady state and is lower than a reference voltage in an abnormal state. Blocking device.
16. The method of claim 15,
And the two nodes are nodes drawn from the input winding section.
12. The method of claim 11,
Wherein the switch unit is at least one of a semiconductor switch, a circuit breaker, a magnetic switch or a relay, or between the power system network and the short-circuit current abatement device or between the short-circuit current abatement device and the load. Current reduction device.
12. The method of claim 11,
And an alarm generating unit for generating an alarm when it is determined that a short circuit or an overcurrent occurs in the load in accordance with the detection result of the abnormal state sensing unit, wherein the alarm is an audible or visual alarm .
An R input terminal, an S input terminal and a T input terminal for receiving three-phase power from the power grid network;
An R output terminal connected to the load, an S output terminal and a T output terminal; And
And a short-circuit current reducing device according to any one of claims 1 to 9, connected between each of the input terminals and the neutral point,
Wherein the first input terminal of each of the shortcircuit reduction devices is connected to the R input terminal, the S input terminal, and the T input terminal, respectively, the second input terminal of each of the shortcircuit reduction devices and one end of the first and second output terminals are connected to the neutral point And the other of the first and second output terminals of the short-circuit current reducing device is connected to the R output terminal, the S output terminal, and the T output terminal, respectively.
20. The method of claim 19,
Wherein the three-phase short-circuit current reducing device is integrally formed.
20. The method of claim 19,
And at least one transformer connected in cascade with the short-circuit current reducing device.
22. The method of claim 21,
Wherein at least one of said at least one transformer is said short-circuit current reducing device.
1. A distribution board including a main breaker and a branch circuit breaker,
And a short-circuit current reducing device for reducing the short-circuit current on the load side,
The short-circuit current reducing device according to any one of claims 1 to 9, wherein the short-circuit current reducing device is a short-circuit current reducing device.
24. The method of claim 23,
Further comprising at least one transformer cascaded with said short-circuit current abatement device.
25. The method of claim 24,
Wherein at least one of said at least one transformer is said short-circuit current abatement device.
24. The method of claim 23,
And an abnormal state sensing unit connected to the short-circuit current reducing unit to sense an abnormal state of the load,
And disconnects at least one of the main breaker and the branch breaker when it is determined that a short circuit or an overcurrent occurs in the load according to the detection result of the abnormal state sensing unit.
27. The method of claim 26,
Wherein the abnormal state sensing unit senses a current flowing in the first input terminal, the second input terminal, or the first and second output terminals.
27. The method of claim 26,
Wherein the abnormal state sensing unit senses a voltage between two nodes in the shortcircuit reduction apparatus, wherein the voltage between the two nodes is less than a reference voltage in a normal state and exceeds a reference voltage in an abnormal state.
29. The method of claim 28,
Wherein one of the two nodes is a node drawn from the output winding section, and the other of the two nodes is a node drawn from the input winding section.
27. The method of claim 26,
Wherein the abnormal state sensing unit senses a voltage between two nodes in the shortcircuit reduction device, wherein the voltage between the two nodes exceeds a reference voltage in a steady state and is lower than a reference voltage in an abnormal state.
31. The method of claim 30,
Wherein the two nodes are nodes drawn from the input winding section.
27. The method of claim 26,
Further comprising an alarm generating unit for generating an alarm when it is determined that a short circuit or an overcurrent occurs in the load in accordance with the detection result of the abnormal state sensing unit, and the alarm is an audible or visual alarm.
A cable reel apparatus comprising a cable reel for winding a cable and an outlet provided for electrically connecting the cable and a load device,
And a short-circuit current reduction unit connected between the cable and the socket to reduce the short-circuit current on the load side,
Wherein the short-circuit current reducing section is a short-circuit current reducing device according to any one of claims 1 to 9.
A cable reel apparatus comprising a cable reel for winding a cable and an outlet provided for electrically connecting the cable and a load device,
And a short-circuit current reduction unit connected between the cable and the socket to reduce the short-circuit current on the load side,
Wherein the short-circuit current reduction unit is the short-circuit current reduction device of claim 11.

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