KR101894002B1 - A detection circuit for degradation of a surge protective device - Google Patents

Abstract

In the present invention, a PTC (Positive Temperature Coefficient Thermistor) thermistor is connected in series to a surge protector and connected in parallel to a load, so that the operating voltage of the surge protector is reduced when the surge protector degrades due to overvoltage. To a surge protector, which is connected to the surge protector.
The characteristic deterioration detecting circuit 100 of the present invention includes a surge protector 110 connected in parallel to a load 10 to protect the load 10 from surge voltages at input terminals LINE and GND, (PTC) 120, which is connected in series to the surge protector 110 and whose resistance increases according to the leakage current Is of the surge protector 110, and the voltage of the common connection terminal of the PTC 120 and the surge protector 110 A comparator 130 for comparing the input voltage V _IN with a predetermined reference voltage V _REF to detect the deterioration of the characteristics of the surge protector, And a relay 150 that cuts off the load current when the photodetector 140 is turned on.

Description

[0001] The present invention relates to a surge protective device,

The present invention relates to a circuit for detecting the deterioration of a surge protector for detecting degradation of a surge protector, and more particularly, to a surge protector having a surge protector connected in series to a surge protector by connecting a PTC (Positive Temperature Coefficient Thermistor) And more particularly, to a circuit for detecting a characteristic deterioration of a surge protector that transmits a reduction in the operating voltage of the surge protector to the outside through an LED indicator or blocks a load current through a separate relay.

In general, a surge protection device (SPD) is used to protect a load from a surge voltage generated when a lightning stroke or a power switch is turned on and off. A TVD (Transient Voltage Suppressor diode) diode or a metal oxide varistor When the surge voltage exceeds the operating voltage of the surge protector by connecting in parallel to the input side, the internal resistance momentarily decreases and the short-circuit state is maintained to limit the surge current flowing into the load.

On the other hand, the surge protector is very difficult to detect the degradation of its characteristics because the internal resistance is very high when the input voltage is normal and the leakage current is fine. Therefore, when the surge protector is permanently short- There is a problem in that it is difficult to take measures in advance in response to the characteristic deterioration.

FIG. 1 is a schematic diagram showing a conventional surge protector protection circuit. In the conventional surge protector protection circuit, a thermal fuse (FUSE) is connected in series to a surge protector (SPD), and a surge protector When the fuse is operated by connecting LEDs in parallel, it is possible to transmit to the outside whether the surge protector (SPD) is damaged or replaced through a separate indicator light (LED).

However, such a conventional protection circuit is effective in preventing fire due to a fault current when the surge protector (SPD) is permanently damaged, but its operation voltage is decreased due to the degradation of the surge protector (SPD) It is impossible to detect it, so that the overheating of the component is continued due to the leakage current until the operation of the fuse, and the input voltage is lowered.

KR 10-1253229 B1 KR 10-1429078 B1

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a surge protector, in which a surge protector is deteriorated in characteristics after a PTC thermistor is connected in series, When the PTC resistance is raised, the operating voltage of the surge protector is continuously detected. If it is lower than the preset reference voltage, the adjacent LED is turned on, and if necessary, the load (LOAD) A surge protector for detecting a characteristic of the surge protector;

According to an aspect of the present invention, there is provided a surge protector including: a surge protector connected in parallel to a load to protect a load from a surge voltage; and a surge protector connected in series to the surge protector, A comparator for comparing a voltage of a common connection terminal of the PTC and the surge protector to a predetermined reference voltage to detect degradation of the characteristics of the surge protector; And a photodetector that is turned on when the comparator senses a deterioration of the characteristics of the surge protector to indicate a degradation of the characteristics.

The characteristic deterioration detection circuit of the surge protector further includes a relay for interrupting a current of the load when the photodetector is lit, thereby limiting the internal overheating of the surge protector when an overvoltage input or a surge protector degrades, ) Voltage of the surge protector and the predetermined reference voltage of the surge protector are input to the comparator and the relay is controlled by the output of the comparator to shut off the load current.

According to another aspect of the present invention, there is provided a circuit comprising: a surge protector connected in parallel with a load to protect a load from a surge voltage; and a series circuit connected to the surge protector, (PTC) connected in parallel to the PTC (PTC) and turned on in accordance with the voltage of the PTC (PTC), the brightness of the surge protector (LED) that indicates a degraded state of the surge protector. When an overvoltage input or a surge protector deteriorates, the internal overheating of the surge protector is limited and the LED current intensity is proportional to the PTC voltage Is adjusted.

The characteristic deterioration detection circuit of the surge protector according to the present invention uses a PTC thermistor connected in series to a surge protector to increase the resistance of the PTC due to heat due to leakage current even when the characteristics of the surge protector deteriorate, It is possible to prevent a component from being overheated due to leakage current by taking measures beforehand for detecting a drop and preventing a fire from occurring or a malfunction due to a low input voltage.

1 is a schematic view showing a protection circuit of a conventional surge protector,
FIG. 2 is a circuit diagram showing a characteristic deterioration detecting circuit of a surge protector according to a preferred embodiment of the present invention.
FIG. 3 is a circuit diagram illustrating a circuit for detecting the degradation of characteristics of a surge protector according to another embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. The following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

FIG. 2 is a circuit diagram illustrating a circuit for detecting the degradation of characteristics of a surge protector according to a preferred embodiment of the present invention. Referring to FIG.

2, the circuit for detecting the degradation of the surge protector according to the preferred embodiment of the present invention is connected in parallel to the load 10 to detect the load 10 from the surge voltage at the input terminals LINE and GND, (PTC) 120 connected in series to the surge protector 110 to increase the resistance in accordance with the leakage current Is of the surge protector 110, a surge protector 110 for protecting the surge protector 110, A comparator 130 for comparing the voltage V _IN of the common connection terminal of the PTC 120 and the surge protector 110 with a predetermined reference voltage V _REF to detect degradation of the characteristics of the surge protector 130, A photodetector 140 which is turned on when the characteristic of the surge protector is deteriorated to indicate the degradation of the characteristics and a relay 150 which blocks the current of the load when the photodetector 140 is turned on, (PTC) in the event of a degradation in the characteristics of the surge protector, The operation voltage of the surge protector in inverse proportion to the voltage and the preset reference surge protector degradation reference voltage are input to the comparator 130 and the relay 150 is controlled by the output of the comparator 130 to shut off the load current.

Referring to FIG. 2, a PTC thermistor 120 is connected in series between an input voltage V _LINE and a surge protector 110 to sense degradation of a surge protector (SPD) 110, and a surge protector (SPD) 110 sense voltage (V _iN) of a) is a comparator (CM, comparator; is connected to the positive (+) terminal 130), the input circuit. The reference voltage V _REF connected to the negative terminal of the comparator CM 130 is a characteristic deterioration reference voltage of the surge protector 110 and its setting is determined by the operating voltage V of the surge protector 110 _SPD , Maximum Operating Voltage or Reverse Stand-off Voltage) and its detection error (V _DIFF ). Accordingly, the reference voltage V _REF can be obtained according to the following Equation 1, and the lower the detection error V _DIFF , the earlier the characteristic deterioration of the surge protector 110 can be detected.

In the normal state of the surge protector 110, the operating voltage V _SPD of the surge protector 110 is equal to or greater than the input voltage V _LINE , and the sensing voltage V _IN of the surge protector is input The comparator CM 130 outputs 1 and the internal LED of the photodetector 140 becomes OFF since the voltage is equal to the voltage V _LINE and is greater than the reference voltage V _REF . As the photodetector 140, an LED or the like isolated from an output terminal may be used.

V _SPD > = V _LINE ,
V _IN = V _LINE ,
V _IN > V _REF ,
LED = OFF

If the operating voltage of the surge protector 110 is lower than the input voltage V _LINE as shown in the following Table 2, the leakage current Is increases in the state where the surge protector 110 is in a degraded state or an overvoltage input state, When the internal resistance value of the PTC 120 becomes high, the PTC voltage V _PTC rises, and accordingly, the surge protector 110 limits the internal overheating. At this time, since the reference voltage V _REF is proportional to the input voltage V _LINE , the sensing voltage V _IN becomes smaller than the reference voltage V _REF , the comparator CM 130 outputs 0, 140 are turned on.

V _IN = V _{LINE -} V _PTC ,
V _IN < V _REF ,
LED = ON

Generally, if the surge current occurs beyond the PTC maximum allowed current, the PTC 120 will break and become permanently open. If the surge protector 110 also becomes permanently open at the same time, the sense voltage V _IN becomes equal to the ground voltage V _GND through the resistor R 1, which is again less than the reference voltage V _REF , The comparator (CM) 130 outputs 0, and the LED 140 becomes ON.

V _IN = V _GND ,
V _IN < V _REF ,
LED = ON

The surge protector degradation detection circuit 100 according to this preferred embodiment can precisely maintain the degradation detection range by setting the reference voltage V _REF , but a comparator (CM) circuit must be added.

FIG. 3 is a circuit diagram illustrating a circuit for detecting the degradation of the characteristics of a surge protector according to another embodiment of the present invention.

3, a surge protector of a surge protector according to another embodiment of the present invention includes a surge protector (not shown) connected in parallel to a load 10 to protect the load 10 from a surge voltage (PTC) 220 that is connected in series to the surge protector 210 and increases in voltage with an increase in resistance in proportion to an increase in the leakage current of the surge protector, (LEDs) 230 that are connected in parallel and are turned on according to the voltage of the PTC (PTC) to change the brightness and display the characteristic degradation state of the surge protector in an analog manner. When the overvoltage input or the characteristics of the surge protector deteriorates Limiting the internal overheating of the surge protector and adjusting the intensity of the LED current proportional to the PTC voltage.

Referring to FIG. 3, the LED current (I _LED ) is proportional to the PTC voltage V _PTC , as shown in the following equation (2).

The LED current (I _LED ) is very low as shown in the following Table 4 when the surge protector 210 is in a normal state.

V _IN = V _LINE ,
V _PTC = 0,
I _LED = 0

When the operating voltage of the surge protector 210 is lower than the input voltage V _LINE as shown in the following Table 5, the leakage current Is increases and the PTC 220 , The PTC voltage V _PTC rises and the internal overheating of the surge protector 210 is limited. At this time, the LED current I _LED rises in proportion to the PTC voltage (V _PTC ).

V _LINE > V _IN ,
V _PTC > 0,
I _LED > 0

Generally, if the surge current occurs beyond the PTC maximum allowable current (Maximum Fault Current), the PTC 220 will break and become permanently open. If the surge protector 210 also becomes permanently open at the same time, the LED current I _LED is inversely proportional to the sum of the R7 and R8 resistances and proportional to the input voltage V _LINE , as shown in Equation 3 below.

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 embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

100,200: Detecting circuit of surge protector degradation characteristic 10: Load
110,210 Surge protector 120,220 PTC (PTC)
130: comparator 140: photodetector
150: Relay 230: LED (LED)

Claims (3)

A surge protector connected in parallel to the load to protect the load from surge voltage,
(PTC) connected in series to the surge protector to increase the resistance according to a leakage current of the surge protector,
A comparator for comparing the voltage of the common connection terminal of the PTC and the surge protector to a predetermined reference voltage VREF to detect the degradation of the surge protector;
And a photodetector that is turned on when the comparator senses a deterioration in the characteristics of the surge protector,
The reference voltage (V _REF )
(V _SPD ) and a detection error (V _DIFF ) of the surge protector, the setting of the reference voltage for detecting the deterioration of the characteristics of the surge protector,

And the characteristic deterioration of the surge protector can be detected earlier as the preset detection error (V _DIFF ) is smaller. 2. The surge protector according to claim 1,
And a relay for blocking the current of the load when the photodetector is turned on
When the overvoltage input or the characteristics of the surge protector deteriorates, it limits the internal overheating of the surge protector and inputs the operating voltage of the surge protector in inverse proportion to the PTC voltage and the preset reference surge protector degradation reference voltage to the comparator, And the load current is cut off by controlling the relay. A surge protector connected in parallel to the load to protect the load from surge voltage,
(PTC) which is connected in series to the surge protector and whose voltage increases when the leakage current of the surge protector increases,
(LED) which is connected to the PTC in parallel with a resistor R7 and is turned on according to the voltage of the PTC to change the brightness of the PTC so as to analogously display the characteristic deterioration state of the surge protector, &Lt; / RTI &gt;
The current (I _LED ) flowing through the _LED
Equation

Lt; / RTI &gt;
(LED) current intensity in proportion to the _PTC voltage (V _PTC ) while restricting internal overheating of the surge protector when an overvoltage input or a surge protector degrades in characteristics. Characteristic degradation detection circuit.

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