JPH05108992A - Device for detecting abnormal over heat of conductor - Google Patents

Abstract

PURPOSE:To provide a small detecting device with high reliability by providing a temp. switch, a sensor for transmitting such as a piezoelectric element, etc., and a current transformer and transmitting and reporting the abnormal over heat state to gas space or a conductor supporter by means of the vibration of the sensor for transmitting. CONSTITUTION:The power source of a detector is obtained from current flowing in pipe conductors 1a, 1b, contactors 2a, 2b and a contact 3 by the current transformer 5. When the conductors exceed some set temp., the contact of a temp. switch 6 opens and the output voltage of the current transformer 5 is impressed on the piezoelectric element 8. When the temp. switch 6 detects the temp. of the conductors and opens the contact, the load of the current transformer 5 becomes the piezoelectric element 8, its value becomes the same state as infinity so that the output voltage is impressed, which is scores to some hundred times as high as the output voltage at the time of loading a resistance 7. At this time, an oscillation signal from the piezoelectric element 8 becomes an ultrasonic signal and goes to a reception sensor 9 through the pipe conductors 1a or gas space. The output signal of the reception sensor 9 is guided by a level judging equipment 12 by way of an amplifier 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormal overheat detecting device in an energized contact portion inside a metal container of electric power equipment.

[0002]

2. Description of the Related Art To detect abnormal overheating of a power-carrying part of a power device, a temperature sensor such as a thermo label, a thermo camera, a thermocouple, a thermometer or a thermistor is used to check the temperature rise.

[0003]

When the temperature sensor is a thermo label, the price is low, but it cannot be constantly monitored unless a method for detecting a color change is considered, and long-term deterioration is a problem.

In the case of a thermo camera, not only is it expensive and cannot be used easily, but there is a problem in the long-term stability of the sensor part.

In the case of a thermocouple, temperature measuring element or thermistor,
It cannot be directly attached to the conductor from above the electrical insulation, and the temperature conducted to the gas or insulator is measured, so the sensitivity is low,
The influence of other heat sources is large.

The present invention has been made in view of the above problems, and its purpose is to improve performance by using a current transformer as a power source and detecting and reporting an abnormal overheated state of a conductor by a temperature switch and a transmission sensor. An object is to provide a highly reliable abnormal overheat detection device.

[0007]

In order to achieve the above object, the present invention is connected to a current transformer that generates a voltage signal according to a current flowing through a conductor, and a secondary output side of the current transformer. A temperature sensor that detects the temperature of the conductor and a transmission sensor that generates an oscillation signal according to the detection signal of the temperature sensor constitute an abnormal overheat detecting device for the conductor.

[0008]

[Function] The temperature switch, the piezoelectric element, and the current transformer are provided, and the abnormal overheated state of the conductor is transmitted to the gas space or the conductor support by the vibration of the piezoelectric element to notify the abnormal state. Further, a piezoelectric element that is difficult to vibrate at a commercial frequency is vibrated with a differential waveform obtained by saturation of the magnetic material of the core of the current transformer.

[0009]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 shows an abnormal overheat detecting apparatus according to an embodiment of the present invention. In FIG. 1, 1a and 1b are aluminum pipe conductors which are conductors, 2a are contacts joined to the pipe conductor 1a, and 2b is a pipe. A contact 3 joined to the conductor 1b, 3 a contact joined to the contacts 2a and 2b, 4
Is a ring spring. 5 is a pipe conductor 1a and a contactor 2a
A current transformer disposed between the current paths, 6 is a temperature switch electrically connected to the current transformer 5 via a resistor 7, and 8 is a piezoelectric element which is a transmission sensor connected in parallel with the temperature switch. Then, the current transformer 5, the temperature switch 6, the resistor 7 and the piezoelectric element 8 constitute an abnormal overheat detecting device as shown in FIG. Reference numeral 9 is a receiving sensor, 10 is an amplifier, 11 is a detector, and 12 is a level judging device.

A temperature fuse and a temperature-sensitive magnetic switch are used as the temperature switch, and an AE sensor, an ultrasonic sensor, a piezoelectric buzzer, etc. are used as the sensor in addition to the piezoelectric element.

Pipe conductors 1a, 1b, contacts 2a, 2b
And the current of the detector 3 is obtained from the current flowing through the contact 3 by the current transformer 5. When the conductor exceeds a certain set temperature Ts, the contact of the temperature switch 6 is opened, and the output voltage of the current transformer 5 is applied to the piezoelectric element 8.

Generally, the current transformer has a structure as shown in FIGS.
As shown in, the saturation of the magnetic material in which the output voltage waveform changes from a sine wave to a differential waveform due to the saturation of the magnetic material of the core is
The value of the load resistance R _L of the current transformer is too large, or the load current I _O
Occurs when it is too large. Using this principle, a differential waveform is applied to the piezoelectric element 7 (whose resistance value can be regarded as ∞) that is difficult to vibrate at a normal commercial frequency, so that vibration is generated at the overheating temperature.

When the temperature switch 6 detects the temperature of the conductor and the contact is opened, the load of the current transformer 5 becomes the piezoelectric element 8 (capacitive load) and its value becomes the same state as ∞, and the output voltage becomes As shown in FIG. 5, the output voltage having a value R _L of the resistor 7 that is several tens to several hundreds times higher than the output voltage under load is applied.

In the detector of FIG. 1, the oscillating signal from the piezoelectric element 8 becomes an ultrasonic signal and reaches the receiving sensor 9 through the pipe conductor 1a or the gas space. The output signal of the reception sensor 9 is amplified by the amplifier 10 and then detected by the detector 11
After being detected by, it is guided to the level determiner 12.
The level determiner 12 issues an alarm when the level of the detected signal exceeds a predetermined value.

The abnormal overheat detecting device of FIG. 1 has the following advantages.

(1) Since the temperature switch 6 is small and can be arranged near the abnormal heat generating portion of the contact portion of the conductor, it is possible to detect abnormal overheat with high sensitivity. (2) The piezoelectric element 8 is set inside or on the surface of the conductor, and it is not necessary to supply a power source to the piezoelectric element 8, so that the piezoelectric element 8 can be easily attached to the high-voltage conductor. (3) Since the operation stops when there is no current flowing through the conductor, it is possible to identify the heat generating conductor phase and the location by the way the current flows.
(4) High reliability because there are no parts vulnerable to heat and surge currents like semiconductors. (5) Since the temperature sensor 6, the current transformer 5, the piezoelectric element 8, and the resistor 7 can be separately arranged on the conductor,
The direction and position of the ultrasonic waves in the air and the vibration of the AE sensor can be easily attached to make the supporting insulator effective.

FIG. 2 shows an abnormal overheat detecting device according to another embodiment of the present invention. In FIG. 2, a copper bar bus bar 13a is shown.
And 13b are connected by a contact 3 and a spring 14, and are supported by a pedestal 16 by an insulator 15. An electric field shield 17 is provided on the outer circumference of the current transformer 5. The temperature sensor 6 is embedded in the copper bar bus 13a, and the secondary winding of the current transformer 5 is wound around the outer peripheral surface of the copper bar bus.
The transmitting AE sensor (pulsar) 8a is arranged on the copper bar bus bar 13a located in the upper part of the insulator 15, and the receiving AE sensor 9a is arranged in the pedestal 16 located in the lower part of the insulator 15.

According to the abnormal overheat detecting device of FIG. 2, the output signal of the transmitting AE sensor 8a is the copper bar bus bar 13a and the insulator 1.
5, it reaches the receiving AE sensor 9a through the gantry 16 and has the same effect as that of FIG.

[0020]

As described above, the present invention comprises a temperature sensor, a transmission sensor such as a piezoelectric element, and a current transformer, and an abnormal overheated state of a conductor is supported by a vibration of the transmission sensor in a gas space or a conductor. Since it is transmitted to an object to notify the abnormal overheat state, a compact and highly reliable abnormal overheat detection device can be obtained.

[Brief description of drawings]

FIG. 1 is a front sectional view of a conductor abnormal overheat detecting device according to an embodiment of the present invention.

FIG. 2 is a front sectional view of an abnormal conductor overheating detection device according to another embodiment of the present invention.

FIG. 3 is a circuit diagram showing a basic configuration of the abnormal overheat detection device of FIG.

FIG. 4 is an output characteristic waveform diagram of a current transformer in the circuit of FIG.

FIG. 5 is an output voltage characteristic diagram for a through current of a current transformer.

[Explanation of symbols]

1a, 1b ... Pipe conductor, 2a, 2b ... Contact, 3 ... Contact, 5 ... Current transformer, 6 ... Temperature switch, 7 ... Resistance,
8 ... Piezoelectric element that is a sensor for transmission, 8a ... AE sensor,
9 ... Receiving sensor, 9a ... Receiving AE sensor, 13a, 1
3b ... Copper bar bus bar.

Claims (1)

[Claims] 1. A current transformer that generates a voltage signal according to a current flowing through a conductor, a temperature sensor connected to a secondary output side of the current transformer to detect the temperature of the conductor, and a detection by the temperature sensor. A conductor abnormal overheat detection device comprising a transmission sensor that generates an oscillation signal according to a signal.