JP2000209772A - Current limiter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current limiter the current limiting element of which will not be fractured, even when a large overcurrent flow to the element, and maintains a high current limiting ratio. SOLUTION: A current limiter 1 is constituted of a main circuit 2, in which a resistor R1 the electric resistance value which has a positive temperature coefficient is arranged and an auxiliary circuit 3 in which a resistor R2, the electric resistance value of which has a negative temperature coefficient is arranged in parallel with the resistor R1, and the auxiliary circuit 3 is grounded via a switch Sw. In a normal state, most of the electrical current flows to a load 4 through the main circuit 2, but when an overcurrent occurs, the electric current is inhibited from flowing to the load 4, because the ratio between the resistance values of the resistors R1 and R2 is switched so that most of the electrical current flows to the grounded auxiliary circuit 3. Therefore, the current limiter 1 can limit the overcurrent without causing its current limiting element to breakdown.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current limiter for protecting a circuit by limiting an overcurrent flowing in an electric device.

[0002]

2. Description of the Related Art In recent years, with the increase in capacity of electrical equipment, overcurrent generated due to a short circuit accident or the like tends to increase. In such a case, it is economically burdensome to prepare a large circuit breaker that sufficiently satisfies the short-circuit capacity. Recently, it has been practiced to connect a current limiter having a configuration in which a large number of circuit breakers having a relatively small breaking capacity are arranged in series, thereby limiting the current and securing a large breaking capacity.

Conventional current limiters include, for example, Fe, Fe-
Use a material that has a relatively low specific resistance at room temperature, such as a Co alloy, and has a large temperature coefficient of electrical resistance so that it has a high specific resistance at high temperatures. Connected in series with the circuit breaker,
The resistance is increased at a temperature generated by Joule heat generated when an overcurrent flows, thereby limiting the overcurrent.

On the other hand, in recent large-capacity current limiting, a large resistance change such as 100 to 1000 times the specific resistance ratio between normal temperature in a steady state and high temperature in a short circuit is required.

However, in the conventional current limiters using Fe and Fe-Co alloys, the specific resistance at room temperature is considerably low at about 10 μΩcm and about 6 μΩcm, respectively, but that at 300 ° C. is eight times that at room temperature. Only about. Therefore, a sufficient current limiting effect could not be obtained.

[0006] Other techniques for obtaining the rate of change of high resistance, Sr positive typical used as the temperature coefficient material of the electrical resistance (PTC), Pb, BaTi0 containing dopants such as Ce ₃ There are ceramics. However, since these materials have a high specific resistance of about 10 Ωcm at normal temperature, the voltage drop becomes large, and it is difficult to use them for high power applications. Further, since the PTC phenomenon depends on a mechanism caused by the grain boundary layer, it is difficult to use the PTC phenomenon for a large current application.

Further, V ₂ O ₃ containing a small amount of Cr or Al
Ceramics are also known to be PTC resistors. However, when the same material shifts from a steady current to an overcurrent, the current is concentrated, and the concentrated portion is rapidly heated and ruptured. For this reason, there is a problem that it is not possible to return to the steady state after the current limiting operation is completed.

As described above, a few techniques have been developed as a current limiter and all of them have been put to practical use. However, improvements have been made in response to recent demands for larger capacity and higher reliability. Is needed. That is, the above Fe, F
e-Co-based current limiting elements are frequently used at present due to their excellent characteristics such as economy, workability, and low resistance at steady state. Not suitable for application.

The above-mentioned BaTiO ₃ or V ₂ O ₃
Although a ceramic PTC resistor such as a system can obtain a large current limiting ratio at the time of overcurrent, it has a fatal defect such as breakage due to overcurrent, and cannot be used as a current limiter for large capacity use as it is.

[0010]

As described above, in ceramic-based PTC resistors such as BaTiO ₃ and V ₂ O ₃ having a high current limiting ratio at present, there is a problem that the element is damaged by overcurrent. Therefore, an object of the present invention is to provide a current limiter that does not break the current limiting element even when a large overcurrent flows and has a high current limiting ratio.

[0011]

According to a first aspect of the present invention, there is provided a current limiter having a main circuit including a first resistor having a positive temperature coefficient and a negative resistance. And a sub-circuit composed of a second resistor having a temperature coefficient of?

With such a configuration, the distribution of the current densities of the main circuit and the sub-circuit arranged in parallel during normal operation and when an overcurrent occurs is switched, so that the overcurrent does not flow to the main circuit. it can. Therefore, the overcurrent can be limited without applying a large load to one resistor element, thereby preventing destruction of the element and recovering the main circuit even if the sub-circuit is broken.

According to a second aspect of the present invention, there is provided the current limiter according to the first aspect, wherein the electric resistance value r1 of the first resistor and the electric resistance value r2 of the second resistor in a steady state are changed. The ratio r1 / r2 is 0.1 or less.

According to a third aspect of the present invention, there is provided the current limiter according to the first aspect, wherein the electric resistance value r3 of the first resistor when the current flows three times or more of the steady state and the electric resistance r3 of the first resistor. Second
Wherein the ratio r3 / r4 of the resistor to the electrical resistance value r4 is 10 or more.

According to a fourth aspect of the present invention, there is provided a current limiter having a main circuit in which a first resistor having a positive temperature coefficient and a third resistor for heat generation are arranged in parallel. And a sub-circuit composed of a second resistor having a negative temperature coefficient and having a negative electric resistance value is arranged in parallel, and the sub-circuit is grounded.

With this configuration, the distribution of the current density between the main circuit and the sub-circuit arranged in parallel at the time of steady state and when an overcurrent occurs is switched, so that the overcurrent does not flow to the main circuit side. it can. Therefore, the overcurrent can be limited without applying a large load to one resistor element, thereby preventing destruction of the element and recovering the main circuit even if the sub-circuit is broken.

According to a fifth aspect of the present invention, in the current limiter according to the fourth aspect, the electric resistance value r1 of the first resistor and the electric resistance value r2 of the second resistor in the steady state are set.
And the ratio r1: r2: of the electrical resistance value r5 of the third resistor to the third resistor.
r5 is 1:10 or more: 5 or more.

According to a sixth aspect of the present invention, in the current limiter according to the fourth aspect, the electric resistance value r3 of the first resistor when the current flows at least three times the steady state, and The electrical resistance r4 of the second resistor and the electrical resistance r of the third resistor
The ratio r3: r4: r6 to 6 is 1: 0.1 or less: 0.5
It is characterized by the following.

According to a seventh aspect of the present invention, in the current limiter, a first resistor having a positive temperature coefficient and a third resistor for heat generation are arranged in parallel. Features. With such a configuration, the speed of the overcurrent limiting operation can be improved.

According to an eighth aspect of the present invention, in the current limiter according to the first or fourth or seventh aspect, the resistors are close to each other via an insulator. The bundled outer circumference is covered with a heat insulating material.

According to a ninth aspect of the present invention, in the current limiter according to the first or fourth or seventh aspect, the first resistor is connected at room temperature (for example, from -30 ° C to + 30 ° C).
(C) is not less than 40 μΩcm and not more than 10 Ωcm, and the rate of increase in electric resistance with increasing temperature from room temperature to 800 ° C. is 5 times or more.

According to a tenth aspect of the present invention, in the current limiter of the ninth aspect, the first resistor is made of iron, N
i, Co, B, Fe-Co alloy, or Fe-Ni alloy.

According to a twelfth aspect of the present invention, in the current limiter according to the ninth aspect, the first resistor includes a B resistor.
It is characterized by being an aTiO ₃ -based oxide or a V ₂ O ₃ -based oxide.

According to a twelfth aspect of the present invention, in the current limiter of the ninth aspect, the first resistor is a composite material of a polymer resin and conductive particles. According to a thirteenth aspect of the present invention, in the current limiter according to the first or fourth aspect, the second resistor has a specific resistance of 0.5 at room temperature (for example, −30 ° C. to + 30 ° C.). 4Ωcm
The resistivity is not more than 10 ⁶ Ωcm and the rate of decrease in electric resistance with a temperature rise from room temperature to 200 ° C. is 1/10 or less.

The present invention according to claim 14 provides the invention according to claim 13
3. The current limiter according to claim 2, wherein the second resistor is VO ₂
It is characterized by being a system oxide. According to a fifteenth aspect of the present invention, in the current limiter of the thirteenth aspect, the second resistor is a LiCo-based oxide, a Se-based intermetallic compound, or an Sb-based intermetallic compound. And

The present invention according to claim 16 provides the invention according to claim 13
2. The current limiter according to claim 1, wherein the second resistor is Ag ₂
It is an S-based sulfide. The present invention according to claim 17 is the current limiter according to claim 13,
The second resistor is made of boron.

According to the present invention, in the current limiter according to the fourth or seventh aspect, the third resistor has a specific resistance of about 0.2 Ωcm or more at around room temperature.
The resistance value is equal to or less than 00 Ωcm, and is an electric resistance value between the electric resistance value of the first resistor and the electric resistance value of the second resistor at the temperature at the time of steady state and overcurrent.

The present invention described in claim 19 provides the present invention according to claim 18.
3. The current limiter according to claim 2, wherein the third resistor is Ni-
It is a Cr-based alloy, Ba-Ti-based oxide, or SiC.

According to a twentieth aspect of the present invention, there is provided a current limiter according to the first or fourth aspect, wherein the current limiter according to the first or fourth aspect includes means capable of disconnecting the ground of the sub-circuit. A current limiter characterized in that only a main circuit can be switched to a circuit inserted in series between a load and a power supply by providing the circuit.

[0030]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following drawings, the same symbols indicate the same or corresponding parts.

(First Embodiment) First, the configuration of a current limiter according to a first embodiment of the present invention will be described with reference to FIG.

In FIG. 1, a current limiter 1 includes a resistor R
1 and a sub-circuit 3 in which a resistor R2 is disposed in parallel with the main circuit 2. The main circuit 2 is connected to a load 4 such as an electric product. Circuit 3
Are grounded via the switch Sw.

In a steady state, most of the current flows to the load 4 through the main circuit 2. However, when an overcurrent occurs, the resistor R1 of the main circuit 2 is connected so that most of the current flows to the sub-circuit 3 which is grounded.
The operation is such that the ratio of the resistance value of the resistor R2 of the sub-circuit 3 is switched.

As a result, the current is prevented from flowing to the load 4 when an overcurrent occurs. The above current limiter 1
The operation in which the distribution of the current to the main circuit 2 and the sub-circuit 3 is switched will be described with reference to FIG.

First, the resistor R1 of the main circuit 2 has a low resistance value r1 in a temperature range relatively close to normal temperature in a steady state. Due to the occurrence of the overcurrent, the resistor R1 self-heats due to the Joule heat, and the temperature rises from the steady-state temperature T1 to the overcurrent-occurring temperature T2. The resistor R1 is made of a material whose resistance value increases with a rise in temperature. So to speak, resistor R
Reference numeral 1 denotes a PTC element whose electric resistance has a positive temperature coefficient.

On the other hand, the resistor R2 of the sub-circuit 3 has a high resistance value r2 at the temperature T1 in a steady state, but has a high resistance value R2 when an overcurrent occurs.
It is made of a resistor material having a negative temperature coefficient such that the resistance value drops sharply to r4 when the temperature reaches T2 due to heat transfer from 1. So to speak, NTC element and CTC
(Rapidly changing resistor) element.

The resistance values of the resistance values r1 to r4 are set to appropriate levels according to the use of the current limiter 1. Ideally, the resistance value r1 should have no voltage loss in a steady state, and a sufficiently low value is required. On the other hand, the resistance value r2 is ideally such that almost no current flows through the resistor R2, and the ratio of r1 / r2 needs to be sufficiently small. When an overcurrent occurs, it is ideal that the resistor 1 and the resistor R2 are reversed, and the resistance value r3 is high and r4 is sufficiently low. That is, it is preferable that the r3 / r4 ratio is sufficiently large. When current stops flowing on the resistance side of r3, the resistor R1
As a result, the temperature of the entire current limiter 1 decreases, and the resistance value returns to a steady state, and the current distribution of the main circuit 2 and the sub circuit 3 also returns.

Here, the resistor R1 has, for example, a specific resistance at room temperature of 40 μΩcm or more and 10 Ωcm or less,
A resistor whose electrical resistance increases with a temperature rise from room temperature to 800 ° C. at least 5 times is used. Also, the resistor R2 is
For example, the specific resistance at room temperature is 0.4 Ωcm or more and 10 ⁶ Ω
cm or less, and a rate of decrease in electrical resistance with a temperature rise from room temperature to 200 ° C. is 1/10 or less.

In the case of a conventional current limiter using only a PTC resistor, there is a problem that if the temperature is rapidly increased with a large current, the PTC element is cracked and destroyed and cannot be recovered. It does not break down because it flows to the CTC (NTC) element.

Even if the resistor R2 of the sub-circuit 3 is damaged, the main circuit 2 can be energized and large damage due to a power failure of the load 4 at the time of recovery can be avoided. In addition, conventional PTC
BaTiO ₃ , which is a typical material of the device, has its PTC
Since the phenomenon is based on the potential barrier at the grain boundary, it has a voltage dependency, and could not be used for large currents such as power.
The resistor R1 in the configuration of the current limiter 1 can be used because a large current is limited.

The temperature T1 in the steady state shown in FIG.
(−30 ° C. to + 30 ° C.) in general, but a temperature set according to use conditions may be used. The ratio r1: r2 of each resistance value at the temperature T1 is 1:10 or more, preferably 1:50 or more.

The setting of the temperature T2 at the time of occurrence of overcurrent is also determined by the use conditions. For example, the ratio r3: r4 of each resistance value at the temperature T2 when a current more than three times the steady state flows is 1
It is 0 or more, and preferably 1 or more.

The material of the resistor R2 of the sub-circuit 3 is desirably a CTC resistor whose electric resistance rapidly decreases at a critical temperature in the range of about 60 ° C. to several hundreds ° C. As such a CTC resistor, a VO ₂ system and an Ag
There is a ₂ S system.

[0044] VO ₂ system CaO to V ₂ O _5, SrO, B
Basic oxides such as aO, PbO and P ₂ O ₅ , SiO
₂ , it is obtained by mixing and dissolving acidic oxides such as B ₂ O ₃ , heat-treating in an appropriate weak reducing atmosphere, and then quenching.

When the temperature of the obtained VO ₂ is raised,
The transition between the semiconductor and the metal occurs around ℃, and the electric resistance sharply decreases. As the resistor R2 in this embodiment, a V ₆₀ B _40- based oxide was used. The electric resistance around room temperature is 3 × 10 ₄ Ω, and it drops sharply around 70 ° C.
It drops to about 0.7Ω at 0 ° C.

When the resistor is a VO ₂ single crystal, the crystal collapses due to the above transition. However, in the case of the composite oxide as in this embodiment, a semi-glass-like oxide is formed in the gap between the VO ₂ fine crystals. It has a characteristic that it does not collapse even when it is displaced because it has a structure with objects.

Like the VO ₂ -B-based oxide, the CTC resistor includes VO ₂ -P-based oxides (V ₈₄ P ₁₁ Ca ₅ -O, V ₇₄
P ₂₁ Ba ₅ —O), VO ₂ —Si-based oxides and Ag ₂
S-based sulfides are also applicable. Further, it is possible to use a material which is not CTC but has a large rate of decrease in resistance in NTC in which the electric resistance has a negative temperature coefficient. Transition metal oxides such as Li ₈ Co ₉₂ oxide and Li ₈ Co ₄₆ Ni ₄₆ oxide;
Alternatively, selenium compounds such as WSe and ReSe ₂ or Mg
Intermetallic compounds such as ₃ Sb ₂ can be used. B (boron) also has an effective NTC property as a metal material.

On the other hand, the material of the resistor R1 of the main circuit 2 is a PTC resistor that has a low resistance in a steady state near room temperature and increases in electrical resistance as the temperature rises to several hundred degrees centigrade. The VO ₂ -B-based oxide C of the resistor R2 in this embodiment
Since TC is 1 ohm or less at 100 ° C. or more, if the electric resistance of the resistor R1 is 100 ohm or more, the current density distributed to the main circuit is about 1%.

At room temperature, iron or N
There are metal materials such as i, Co, B, Fe—Co alloy, and Fe—Ni alloy. As oxide-based materials, V ₂ O ₃ and B
There is the aTiO ₃ system.

In the V ₂ O ₃ system, there is (V _0.997 Cr _0.003 ) ₂ O ₃ in which part of V is substituted with Cr, and in the BaTiO ₃ system, Ba is partially substituted with Pb (Ba ₅₀ Pb ₅₀ ) Ti.
O ₃ there is.

In the polymer system, a material in which conductive particles are composited with a polymer resin such as a polyethylene resin or a silicone resin also exhibits remarkable PTC characteristics. As the conductive particles, Cu,
There are Ag, C, Ni, and Al. A composite material in which 50 wt% of carbon is dispersed as conductive particles in a polyethylene resin is from 0.4 Ωcm at room temperature to 400 Ωcm at a temperature of about 130 ° C.
cm.

The resistors R1 and R2 described above.
In order to configure the current limiter 1 by using the material for the resistor R1, heat generated in the resistor R1 in a short time when an overcurrent occurs is generated by the resistor R2.
Need to be communicated to For this purpose, the resistor R1 and the resistor R2 are brought close to each other with an insulator interposed therebetween, and the periphery thereof is covered with a heat insulating material to prevent heat dissipation. That is, the resistors are coated with an insulating thin film such as an enamel film and overlapped, and the outer periphery of the bundle is covered with a heat insulating material such as a ceramic fiber.

In the current limiter configured as described above, when an accident occurs, the current flows to the ground through the sub-circuit 3 in order to suppress the current supply to the accident point, resulting in a large voltage drop. In order to enable the connection of the current limiter of this embodiment even when it is a problem for the whole system, FIG.
, The switch Sw for disconnecting the ground of the sub-circuit 3
Should be provided.

(Second Embodiment) Next, a configuration of a current limiter according to a second embodiment of the present invention will be described with reference to FIG.

In FIG. 3, a resistor R3 is arranged in parallel with the resistor R1 in the main circuit 2 of the current limiter 1 in the first embodiment shown in FIG. This resistor R3 is the heating circuit 5. By adding the resistor R3 of the heating circuit 5, when an overcurrent flows through the main circuit 2, the resistor R1
And the temperature of the resistor R2 can be rapidly increased.

Here, as the resistors R1 and R2, for example, resistors applicable to the resistors R1 and R2 in the first embodiment are used, and the third resistor is
For example, the specific resistance around room temperature is 0.2 Ωcm or more,
It is 500 Ωcm or less, and has an electric resistance value between the electric resistance value of the resistor R1 and the electric resistance value of the resistor R2 at normal and overcurrent temperatures.

Each of the resistors R1, R2, R
The change in the ratio of the resistance values of No. 3 will be described with reference to FIG. FIG.
At the steady-state temperature T1, the resistance R
The resistance value r5 of No. 3 is higher than the resistance value r1 of the resistor R1 of the main circuit 2 and does not generate heat. When an overcurrent flows, the resistor R3 generates heat to reach the temperature T2. At the temperature T2, the resistance value r6 of the resistor R3 is sufficiently higher than the resistance value r4 of the resistor R2, and since the flowing current density becomes smaller, the heat generation decreases, and eventually the temperature returns to the steady temperature T1. .

Resistance values r1 and r2 at steady-state temperature T1:
The ratio of r5 is 1:10 or more: 5 or more, preferably 1: 100 or more: 50 or more. Further, at an overcurrent, for example, at a temperature T2 when a current more than three times the steady state flows, the ratio of the resistance values r3: r4: r6 is 1: 0.1 or less:
0.5 or less, preferably 1: 0.01 or less.
05 or less.

In this embodiment, when an overcurrent occurs, the resistor R
Although a resistor R3 capable of generating heat in a shorter time than Joule heat of 1 is employed, a NiCr alloy having good heat generation efficiency is economical as a material of the resistor R3.

In addition, by using a PTC resistor having a relatively high resistance value, the resistance increases with heat generation, and the resistors R1 and R2 can be heated instantaneously, thereby preventing the accident from spreading. BaTiO ₃ is used as such a resistance material.
Series thermistors and SiC.

In FIG. 4, the resistance value of the resistor R3 needs to be between the resistor R1 and the resistor R2 at both the steady-state temperature T1 and the overcurrent occurrence temperature T2. At the temperature T1, heat generation is suppressed by increasing the resistance value r5 to at least five times the resistance value r1. By making the resistance value r5 smaller than the resistance value r2, the main circuit 2
To reduce the heat loss and the resistance R of the resistance value r2.
Prevent loss to 2.

At the temperature T2, the current flowing to the main circuit 2 is avoided by making the resistance value r6 larger than the resistance value r4. Also,
By making the resistance value r6 smaller than the resistance value r3, a current for heat generation is secured.

In the second embodiment, as in the first embodiment, the resistors R1, R2, and R3 are brought close to each other via an insulator, and the outer periphery of the bundle is bundled. Coated with a heat insulating material such as ceramic fiber.

Also in the second embodiment, a switch Sw for disconnecting the ground of the sub-circuit 3 is provided so as to cope with a case where it is necessary to prevent a voltage drop to the entire system when an overcurrent occurs.

As described above, in the current limiters of the first and second embodiments, the distribution of the current density of the main circuit and the sub-circuit arranged in parallel at the time of steady state and when an overcurrent occurs is switched. This is to prevent current from flowing to the main circuit side.This can be done without applying a large load to one resistor element, preventing element destruction. A reliable current limiter that the circuit can recover can be obtained.

(Third Embodiment) Next, the configuration of a current limiter according to a third embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 5, the current limiter 1 of the third embodiment comprises a resistor R1 of the main circuit 2 and a heating circuit 5
Is a current limiter in which only the resistor R3 is connected in parallel.

The change in the ratio of the resistance values of the resistors R1 and R3 in this configuration will be described with reference to FIG. As shown in FIG. 6, the ratio of the resistance values r1: r5 at the temperature T1 in the steady state is, for example, 1: 100 or more, so that only a very small current flows through the resistor R3. Body R
The temperature T2 is quickly reached by the Joule heat of 3. This amplifies the rate of increase in the resistance value of the resistor R1 due to Joule heat. As a result, the resistance value at the time of abnormality is r3 * r
5 / (r3 + r5).

That is, the current limiter of the third embodiment is characterized in that the speed of the reaction is improved. The materials used for these resistors R1 and R3 are as follows:
A material applicable to each of the resistors R1 and R3 in each of the above embodiments can be used.

Also, in the third embodiment, similarly to the above-described embodiments, the resistors R1 and R3 are used.
Are placed close to each other via an insulator, and the outer periphery of the bundle is covered with a heat insulating material such as ceramic fiber.

[0071]

As described above, by inserting the current limiter comprising the main circuit and the sub-circuit according to the present invention in series between the power supply and the load, when an overcurrent occurs due to an accident, The electrical resistance of the grounded sub-circuit resistor is lower than that of the main circuit resistor due to the Joule heat of the resistor, thereby preventing an overcurrent from flowing to the load. At this time, in the conventional serial arrangement of only the PTC type resistors, there was a problem that the resistors collapsed by heating, but the collapse of the resistors can be prevented by distributing the current to the CTC or NTC resistor. Further, by enabling the connection of the sub-circuit to the ground to be switched, it is possible to prevent the damage due to the voltage drop to the entire system. Further, according to the current limiter according to the present invention in which a resistor for heating is arranged in parallel with a resistor for limiting overcurrent, the speed of the overcurrent limiting operation can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a first embodiment of a current limiter according to the present invention.

FIG. 2 is a diagram showing a relationship between resistance value and temperature of a resistor according to the first embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of a second embodiment of the current limiter according to the present invention.

FIG. 4 is a diagram illustrating a relationship between resistance value and temperature of a resistor according to a second embodiment of the present invention.

FIG. 5 is a circuit configuration diagram of a current limiter according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between resistance value and temperature of a resistor according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Current limiter 2 ... Main circuit 3 ... Sub circuit 4 ... Load 5 ... Heat generation circuit Sw ... Switch

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takanori Nishimura 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant, Inc. 72) Inventor Takashi Kusano 1 Toshiba-cho, Fuchu-shi, Tokyo F-term in the Fuchu factory of Toshiba Corporation (reference) 5G013 AA01 AA02 AA04 AA09 BA01 CA02

Claims (20)

[Claims] 1. A main circuit comprising a first resistor having an electric resistance having a positive temperature coefficient and a sub-circuit comprising a second resistor having an electric resistance having a negative temperature coefficient are arranged in parallel. A current limiter, wherein a ground is provided in the sub-circuit. 2. The current limiter according to claim 1, wherein a ratio r1 / r2 between an electric resistance value r1 of said first resistor and an electric resistance value r2 of said second resistor in a steady state is zero. .
Current limiter characterized by being 1 or less. 3. The electric current limiter according to claim 1, wherein an electric resistance value r3 of said first resistor and an electric resistance value of said second resistor when a current more than three times that in a normal state flows. A current limiter, wherein a ratio r3 / r4 to a value r4 is 10 or more. 4. A main circuit in which a first resistor having an electric resistance value having a positive temperature coefficient and a third resistor for heat generation are arranged in parallel, and a first circuit having an electric resistance value having a negative temperature coefficient. A current limiter, wherein a sub-circuit comprising two resistors is arranged in parallel, and the sub-circuit is grounded. 5. The current limiter according to claim 4, wherein an electric resistance value r1 of said first resistor, an electric resistance value r2 of said second resistor, and said third resistor in a steady state. The ratio r1: r2: r5 to the electrical resistance value r5 of the body is 1:10
Above: A current limiter characterized by being 5 or more. 6. The current limiter according to claim 4, wherein an electric resistance value r3 of said first resistor and an electric resistance of said second resistor when a current of at least three times the steady state flows. Resistance value r
4 and the electric resistance value r6 of the third resistor r3:
A current limiter wherein r4: r6 is 1: 0.1 or less: 0.5 or less. 7. A current limiter wherein a first resistor having a positive temperature coefficient and a third resistor for heat generation are arranged in parallel. 8. The current limiter according to claim 1, 4 or 7, wherein each of said resistors is close to each other via an insulator, and an outer periphery of said resistors bundled is a heat insulating material. A current limiter characterized by being covered. 9. The current limiter according to claim 1, wherein said first resistor has a specific resistance at room temperature of 40 μΩcm or more and 10 Ωcm or less, and is between room temperature and 800 ° C. A current limiter characterized in that the rate of increase in electric resistance with the temperature rise is 5 times or more. 10. The current limiter according to claim 9, wherein
The first resistor is made of iron, Ni, Co, B, Fe-Co.
A current limiter characterized by being an alloy or an Fe-Ni alloy. 11. The current limiter according to claim 9, wherein said first resistor is a BaTiO ₃ -based oxide or a V ₂ O ₃ -based oxide. . 12. The current limiter according to claim 9, wherein
A current limiter, wherein the first resistor is a composite material of a polymer resin and conductive particles. 13. The current limiter according to claim 1, wherein the second resistor has a specific resistance at room temperature of 0.4 Ωcm or more and 10 ⁶ Ωcm or less, from room temperature to 200 ° C. A current limiter characterized in that the rate of decrease in electrical resistance with temperature rise is 1/10 or less. 14. The current limiter according to claim 13, wherein said second resistor is a VO ₂ -based oxide. 15. The current limiter according to claim 13, wherein said second resistor is a LiCo-based oxide, a Se-based intermetallic compound, or an Sb-based intermetallic compound. vessel. 16. The current limiter according to claim 13, wherein said second resistor is made of an Ag ₂ S-based sulfide. 17. The current limiter according to claim 13, wherein said second resistor is boron. 18. The current limiter according to claim 4, wherein the third resistor has a specific resistance of about 0.2 Ωcm to about 500 Ωcm near room temperature,
A current limiter having an electric resistance value between an electric resistance value of the first resistor and an electric resistance value of the second resistor at a constant temperature and an overcurrent temperature. 19. The current limiter according to claim 18, wherein said third resistor is made of a Ni--Cr alloy, Ba--T
A current limiter comprising an i-based oxide or SiC. 20. The current limiter according to claim 1 or 4, wherein means for disconnecting the ground of said sub-circuit is provided so that only said main circuit is connected in series between a load and a power supply. A current limiter capable of switching to a circuit inserted in the current limiter.