JP2869896B2 - Overvoltage protection components - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an overvoltage protection component used to protect a circuit when an overvoltage current flows, and more particularly, to a positive temperature coefficient thermistor (hereinafter, PTC) element. The present invention relates to an overvoltage protection component configured using the same.

[Conventional technology]

In the field of telephones, a fuse made of a fusing metal material and a PTC element made of barium titanate or the like have conventionally been used as an overvoltage protection element in order to provide overvoltage protection when a voltage of 200 V is applied.

However, recently, not only 200V voltage but also 600V
In some countries, the protection when a voltage is applied is also added to the standard, so protection when a voltage of 600 V is applied is required.

[Problems to be solved by the invention]

However, among the conventional overvoltage protection components, those using a fuse are blown out in the 600 V test to perform the protection operation, but similarly blow out in the 200 V test.
In other words, it is blown out in all the voltage load tests.

Under normal use conditions, accidents such as accidentally connecting the telephone to the commercial power source and accidents such as crossing of high-voltage lines are conceivable. Incorrect connection of telephone outlets can often occur due to the carelessness of the user.However, as described above, fuses blow when any overvoltage is applied, so the fuse must be replaced each time. did not become.

On the other hand, the PTC element has a great advantage that the protection operation in the 200V test is possible and that the PTC element can be used repeatedly after the operation is completed. However, when a voltage of 600 V was applied, the device was destroyed, which caused a fire or damage to equipment, so that the device could not be used.

Therefore, there is a need for an overvoltage protection component that can reliably protect even when a voltage of 600 V is applied and that can be used with simple maintenance.

An object of the present invention is to provide an overvoltage protection component that can repeatedly perform protection against an overvoltage when a 200 V voltage is applied and that can reliably perform a protection operation when a 600 V voltage is applied.

[Means for solving the problem]

The overvoltage protection component of the present invention is configured by combining a PTC element, a current fuse, and a thermal fuse. That is, in the overvoltage protection component of the present invention, a current fuse and a temperature fuse are connected in series to the PTC element having electrodes formed on both main surfaces. The thermal fuse is thermally coupled to the PTC element so as to receive heat when the PTC element generates heat.

Further, the thermal fuse has a fusing temperature of the first temperature fuse.
At the time of application of the first voltage having a relationship of voltage <second voltage
The temperature is set between the heating temperature of the C element and the heating temperature of the PTC element when the second voltage is applied.

In addition, the fuse capacity of the current fuse is such that when a current of the same magnitude as when the current flows through the PTC element is used, the time until the PTC element dies is longer than the time until the PTC element attenuates. It is set to be.

[Action and effect of the invention]

In the overvoltage protection component of the present invention, the first
Is protected when a current having a voltage value of? That is, for example, when the first voltage is 200 V, when a current of 200 V flows, overvoltage protection is repeatedly performed by the PTC element.

On the other hand, when the current of the second voltage that is related to the first voltage <the second voltage flows, the protection operation is performed as follows.

First, when the current value at the time of inrush application is relatively small (1 to
In the case of about 4A), the PTC element generates heat. When the heat generation temperature exceeds a certain value, the resistance value of the PTC element decreases, the heat generation further increases, and the PTC element is destroyed. However, in this case, the fusing temperature of the thermal fuse is set to a temperature between the heat generation temperature of the PTC element when the first voltage is applied and the heat generation temperature when the second voltage is applied. Is blown, PT
Prevents destruction of C element and performs overvoltage protection operation.

On the other hand, when the inrush current is large (when the current value is about 40 A), heat generation of the PTC element occurs rapidly, and a temperature difference occurs between the inside and the outside surface of the PTC element. The device is destroyed before it rises and a large current flows. In this case, since the element is destroyed before the surface temperature of the element is sufficiently increased, the element is destroyed before the operation of the thermal fuse. However, since the capacity of the current fuse is set as described above, the current fuse is blown by a large current flowing due to the destruction of the PTC element, thereby protecting against overvoltage.

Therefore, the present invention provides an overvoltage protection component capable of effectively protecting two types of overvoltage currents having a relationship of first voltage <second voltage.

Therefore, if the first voltage is 200 V and the second voltage is 600 V, the protection operation is performed by the PTC element when the 200 V overvoltage is applied, and the protection operation can be performed repeatedly. Also,
When an overvoltage of 600 V is applied, the protection operation is performed by the operation of the temperature fuse or the current fuse, so that the circuit can be protected safely. In addition, since protection against the two types of overvoltage as described above can be performed by a single component, handling is easy. Further, since the protection operation at the time of applying the first voltage is repeatedly performed, maintenance work can be easily performed.

[Explanation of Example]

1 and 2 are a plan sectional view and a side sectional view of an overvoltage protection component according to one embodiment of the present invention.

Referring to FIGS. 1 and 2, the overvoltage protection component 1
It has a structure in which a PTC element 3 is housed in a case 2 made of an insulating material such as plastic or insulating ceramics.

The case 2 includes a case body 2a having an upper opening, and a lid 2b fixed to the case body 2a so as to close the upper opening.

The PTC element 3 has a structure in which electrodes 5a and 5b are formed on both main surfaces of a plate-shaped PTC element 4 made of a material functioning as a positive temperature coefficient thermistor such as barium titanate.

A lead terminal 7 drawn from one end of the thermal fuse 6 is joined to the electrode 5a by solder 8. The thermal fuse 6 is tightly fixed to the PTC element 3 as shown in the figure, so that heat accompanying the heat generation of the PTC element 3 is given to the thermal fuse 6. That is, the thermal fuse 6 is thermally coupled to the PTC element 3.

A narrow current fuse portion 10 is provided on a lead terminal 9 drawn from the other end of the thermal fuse 6. And, as is clear from FIG.
It is drawn out of case 2.

The current fuse portion 10 is configured by making a part of the lead terminal 9 thin.
It is selected to have the following current capacity: In other words, the fuse capacity of the current fuse portion is set to a value equal to the current flowing through the PTC element 3 when the current having the same magnitude as the current flowing through the PTC element 3.
The C element is configured to have a longer time to melt than the time to current decay.

The above-mentioned thermal fuse has a fusing temperature of the PTC element 3 when 200V is applied and a PTC element 3 when 600V is applied.
It is set to a temperature between the heat generation temperature.

The lead terminal 11 is joined to the electrode 5b on the other main surface side of the PTC element 3. The lead terminal 11 is drawn out of the case 2 as is apparent from FIG.

Therefore, the PTC element 3, the thermal fuse 6, and the current fuse section 10 are connected in series between the lead terminals 9, 11.

Next, the operation of the overvoltage protection component 1 of the above embodiment will be described.

Circuit protection operation when an inrush voltage of 200V is applied. When an inrush current of 200V is applied, the PTC element 3
Operates in the same manner as the PTC element used in a conventional telephone and performs a circuit protection operation. That is, the PTC element 3 generates heat due to the supply of the rush current, the resistance value increases, and the protection operation is performed by performing the current limiting operation.

Circuit protection operation when an inrush voltage of 600 V is applied. In this case, the operation is performed depending on whether the current value is small (about 1 to 4 A) or large (when the current value is up to about 40 A). different.

First, when the current value at the time of inrush application is small, it takes a certain time for the PTC element 3 to generate heat, and the entire element generates heat. When the element heat generation temperature exceeds one point temperature, the resistance decreases and the heat generation further increases. In this case, since the fusing temperature of the thermal fuse 6 is set to a temperature between the heating temperature of the PTC element 3 when 200 V is applied and the heating temperature of the PTC element 3 when 600 V is applied, the thermal fuse 6 is blown. Will do.

As a result, the fusing of the thermal fuse 6 causes the lead terminal
The circuit between 9 and 11 is left open to protect the circuit.

On the other hand, when the rush applied current is large, heat generation of the PTC element 3 occurs rapidly, and a temperature difference occurs between the inside and the outside surface of the PTC element 3. Therefore, the PTC element 3 is destroyed before the surface temperature of the PTC element 3 rises sufficiently, that is, before the thermal fuse 6 is blown.

However, in the structure of this embodiment, the current fuse section
Because the fuse capacity of 10 is set as above,
When the PTC element 3 is broken and a large current flows along with it, the current fuse 10 is blown by the large current and the protection operation is performed.

That is, in the overvoltage protection component 1 of the present embodiment, it is possible to effectively protect the circuit when 600 V is applied, regardless of the magnitude of the inrush applied current.

Modified Example In the above embodiment, a fuse element is used as the thermal fuse 6 and the fuse element is fixed to the main surface of the PTC element 3. However, instead of such a fuse element, solder may be used as the thermal fuse. it can. That is, the first
In the structure shown in the figure, the lead terminal 9 is directly soldered to the electrode 5a, and the PTC element 3 when 200V voltage is applied is used as the solder.
If a material having a melting point between the heat generation temperature of the PTC element 3 and the heat generation temperature of the PTC element 3 when a voltage of 600 V is applied is used, the solder can be used as a thermal fuse.

In the illustrated embodiment, the current fuse portion 10 is formed by making a part of the lead terminal 9 thinner. However, a spring terminal is used in place of the lead terminal 9 and a narrow portion is formed in the spring terminal. The current fuse portion may be formed by providing or combining different types of materials in the middle of the lead terminal 9.

Furthermore, if the current fuse is thermally coupled to the PTC element, it is possible to more reliably protect the device from abnormal conditions.

In the above embodiment, the first voltage and the second voltage are 20
Although the case of 0V and 600V has been described, the first voltage <the second
In a field in which protection against two kinds of applied voltages having a relationship of the following voltages is required, the overvoltage protection component of the present invention can be generally used.

[Brief description of the drawings]

FIG. 1 is a plan sectional view of an overvoltage protection component according to one embodiment of the present invention, and FIG. 2 is a side sectional view of an overvoltage protection component according to one embodiment of the present invention. In the figure, 1 is an overvoltage protection component, 2 is a case, 3 is PT
C element, 6 is a thermal fuse, 9 and 11 are lead terminals, and 10 is a current fuse part.

Claims (1)

(57) [Claims] 1. A PTC element having electrodes formed on both main surfaces, a thermal fuse thermally coupled to the PTC element, and electrically connected in series to the PTC element; A current fuse connected in series with the fuse, wherein the thermal fuse has a fusing temperature having a relationship of first voltage <second voltage, and a heat generation temperature of the PTC element when the first voltage is applied; The temperature is between the heat generation temperature of the PTC element when the second voltage is applied, and the fuse capacity of the current fuse is the same as when a current is applied to the PTC element. An overvoltage protection component, wherein the time until the PTC element melts is set to be longer than the time until the current decay of the PTC element.