JPH10327561A - Protective monitor for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the temperature of a rotor measurable even when the rotor is rotated, by converting the quantity of luminance of an illuminant which changes based on the magnitude of an electromotive force into the temperature value of the rotor by using a measurement circuit, and detecting the temperature of the rotor. SOLUTION: Since a thermocouple 4 is used as an element the electromotive force which changes in accordance with the temperature, the temperature of a rotor 2 can be measured by detecting the electromotive force even when the temperature of the rotor is not detected directly. For measuring the electromotive force, the electromotive force is drawn out by using an illuminant 5 wired to the thermocouple 4. Since the illuminant 5 is positioned to the center of the anti-load side end of the shaft of the rotor 2, the relative position of the illuminant 5 from the outside can be maintained constantly. In addition, since a measurement circuit 6 which detects the quantity of luminance of the illuminant 5 is attached to a fixed position faced to the illuminant 5, the quantity of luminance of the illuminant 5 can be detected and measured even when the rotor 2 is rotated. Therefore, the temperature of the rotor 2 can be measured by converting the detected quantity of luminance into the temperature value of the rotor 2 by means of a conversion circuit 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection and monitoring device for a motor by measuring a rotor temperature.

[0002]

2. Description of the Related Art A conventional example of a motor protection / monitoring device will be described with reference to FIG. FIG. 5 is described in JP-A-5-292704. A converter 54 for converting the temperature of the rotor coil 53 of the rotor 52 detected by the temperature sensor 51 into an electric signal; a transmitting unit 56 for digitizing the electric signal and transmitting the stationary portion with the light emitting element 55; A receiving unit 58 having a light receiving element 57 is provided at a position opposing the transmitting unit 56, so that an abnormality in the rotor coil temperature can be detected.

[0003]

However, in the above-mentioned conventional motor protection / monitoring device, since the rotor of the motor is located inside the stator, the temperature information inside the rotor is directly observed from the outside. There was a problem that it was not possible. Further, since the stator side is supported by a bearing, it is difficult to transfer signals via the bearing. Furthermore, since the rotor itself rotates at a high speed during operation, if a temperature measuring device is attached, durability is required from a structural aspect.

[0004] Therefore, the present invention is to electrically or optically execute the temperature measurement result outside the rotor, so that the temperature can be measured even when the rotor is rotating, so that the center of the shaft end can be measured. It is another object of the present invention to provide a motor protection / monitoring device that provides a light emitting body for a motor and issues an alarm to stop the motor based on a measured temperature result when the allowable temperature of the rotor is exceeded.

[0005]

In order to achieve the above object, an invention according to claim 1 is provided on a rotor of an electric motor, wherein a thermoelectric element whose electromotive force changes according to a temperature value is provided. A light-emitting body connected to the rotor and arranged at the center of the shaft end on the non-load side of the rotor, the luminance of which changes based on the magnitude of the electromotive force; and converting the luminance into a temperature value, And a measuring circuit for detecting the temperature state of the above.

According to a second aspect of the present invention, there is provided a thermo label which is installed on a rotor of an electric motor and changes color according to a temperature value;
An optical fiber mounted inside the rotor for detecting the color of the thermo label from the center of the shaft end on the non-load side of the rotor; and converting the color of the thermo label into a temperature value, And a measuring circuit for detecting a state of the motor.

According to a third aspect of the present invention, there is provided a protection and monitoring device for a motor having a rotor and a stator, wherein the conductor is mounted around the rotor at a position orthogonal to a magnetic flux formed by the stator. And a resistor attached to the conductor and changing to a predetermined resistance according to temperature, connected to the conductor, located at the center of the shaft end on the non-load side of the rotor, and when the rotor is rotating. The light emitting device includes a light emitting body whose luminance is changed by a magnitude of an electromotive force generated by the conductor or the resistor, and a measuring circuit which converts the luminance to a temperature value and detects a temperature state of the rotor. It is characterized by the following. The invention according to claim 4 is characterized by comprising an alarm system for issuing an alarm based on the result of the temperature value in the measurement circuit.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. In FIG. 1, 1 is a motor main body, 2 is a rotor of the motor 1, 3 is a conductor embedded in the rotor 2, 4 is a thermocouple attached to a temperature measurement position inside the rotor 2, and 5 is a conductor 3. The luminous body 6 inserted in the closed circuit of FIG.
A measuring circuit disposed at an opposite position outside the rotor to measure the brightness of the rotor, 7 is a conversion circuit for converting the output of the measuring circuit 6 into temperature, 8 is a display of the rotor temperature and an alarm when a predetermined temperature is exceeded. Is a protection monitoring circuit.

The temperature detection is performed by attaching a temperature sensing part whose electromotive force changes depending on the temperature to a specific portion of the rotor 2 of the electric motor, for example, a portion where the temperature of the rotor bar becomes the highest. The temperature can be measured by using the thermocouple 4 as an element whose electromotive force changes with temperature and detecting the electromotive voltage without directly detecting the temperature. Since the rotor 2 rotates during operation, it is difficult to directly extract the electromotive voltage from the rotor to the outside. Therefore, the luminous body 5 wired to the thermocouple 4 is used to optically extract the thermocouple 4 to the outside. Since the light-emitting body 5 is located at the shaft center of the shaft end on the non-load side of the rotor, the relative position from the outside can be kept constant even during the operation of the rotor. Further, by installing a measuring circuit for detecting the luminance of the luminous body at a fixed side position opposite to the luminous body 5, the luminance of the luminous body is detected and the amount is measured even when the rotor is rotating. It is possible to do. Since the luminance of the luminous body has a predetermined characteristic relationship with the thermocouple electromotive voltage, the detected luminance value is converted into a temperature value by the conversion circuit.

When the temperature of the rotor is T1 and the electromotive voltage of the thermocouple is V
1, the luminance of the illuminant when the temperature of the rotor is T2 and the electromotive voltage of the thermocouple is V2 is L1.
Let it be 2. The temperature value is used for display, and at the same time, when a predetermined temperature is exceeded, an alarm or a motor operation stop signal is generated.

During operation of the motor, the rotor 2 is rotating. As for the magnetic flux density inside the motor, B is a value unique to the motor. Assuming that the length of the conductor 21 that intersects this magnetic flux density with B is L, and that this conductor is rotating at a speed V1, the electromotive voltage e1 of this conductor is given by the following equation: Become. If the resistance value of the conductor is R1 based on the temperature T1 of the rotor at this time, the light emitting body 5 attached to the conductor end
Is as follows. I1 = e1 / R1 = (B * L * V1) / R1 At this time, the luminance of the luminous body is L1 due to the relationship with the current value I1. On the other hand, when the temperature of the rotor 2 becomes R2, the conduction current I2 becomes I2 = e2 / R2 = (B * L * V1) / R2, and becomes the luminance L2 of the light emitting body 5. The measuring circuit 6 measures the luminances L1 and L2 to calculate the temperatures T1 and T2.

Even at the rotor temperature T1, when the speed of the conductor 21 of the rotor 2 becomes V2, the conduction current I3 becomes I3 = e3 / R1 = (B * L * V2) / R1 and is measured. The brightness is L3. However, if the current value is corrected to I3a based on the speed detected by the correction circuit 22, I3a = (V1 / V2) * I3 = I1.

A second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the temperature is detected by affixing a thermo label 10 having a specific color depending on the temperature to a location where the temperature of the rotor 2 of the electric motor becomes the highest. When the color changes depending on the temperature, the temperature can be measured by detecting the color instead of directly detecting the temperature. Since the rotor is rotating while driving,
It is impossible to directly extract the color state of the thermolabel 10 from the rotor to the outside.

Therefore, by connecting the center of the shaft end on the load side of the rotor with the thermo label 10 by an optical fiber 11, the color of the thermo label is detected from the non-load side of the rotor which is one end of the optical fiber. It is possible to do. Also,
Since one end of the optical fiber opposite to the thermo label is located at the center of the shaft, the relative position from outside remains unchanged even during the trial run of the rotor rotation. By attaching a measurement circuit for detecting the color of the thermolabel 10 at the fixed side position, the color of the thermolabel 10 can be detected and the temperature can be measured even when the rotor is rotating. As in the first embodiment, the conversion circuit converts the color into a temperature value.

A third embodiment of the present invention will be described with reference to FIG. The present embodiment is for the case where the temperature of the rotor is measured averagely only during the operation of the motor, and the temperature is set at a position orthogonal to the magnetic flux of the stator in the axial direction of the rotor. In this case, an electromotive force generated by arranging a conductor having a variable resistance value is applied. The luminous body is put in the closed circuit of the arranged conductor, and the luminance is measured from the outside of the rotor by the same method as described above to measure the temperature.

Here, the electromotive force generated in the conductor is determined by the arrangement and magnetic flux of the conductor, and the current of the closed circuit is determined by the resistance value of the rotor that changes with temperature. As a result, the luminance of the luminous body has a correlation with the temperature, so that the luminance is measured outside in the same manner as described above.

However, since the electromotive force is proportional to the moving speed of the conductor, that is, the rotating speed of the rotor, the temperature value is calculated after correcting the luminance of the luminous body by the detected value of the rotating speed in the correcting circuit.

A fourth embodiment of the present invention will be described with reference to FIG. The present embodiment is a case where the temperature of a specific portion of the rotor is measured during operation of the motor, and a conductor is arranged at a position orthogonal to the magnetic flux of the stator in the axial direction of the rotor, and a temperature measurement position is set. Is mounted with a temperature measuring resistor having a temperature characteristic. Reference numeral 31 denotes a resistance temperature detector mounted at a temperature measurement position inside the rotor 2. Since the resistance of the conductor itself is small and can be ignored, the current flowing through the conductor 32 is determined by the resistance value of the resistance temperature detector 31, and the temperature can be calculated as in FIG. In addition, the temperature is calculated by putting the luminous body in this closed circuit and measuring the luminance amount from outside the rotor in the same manner as described above.

[0019]

As described above, according to the present invention, the temperature can be measured while the rotor is rotating by electrically or optically performing the temperature measurement result outside the rotor. The measured temperature is constantly monitored, and if the temperature exceeds the allowable temperature of the rotor, an alarm for stopping the motor can be issued.

[Brief description of the drawings]

FIG. 1 is an electric motor protection and monitoring device according to a first embodiment of the present invention.

FIG. 2 is an electric motor protection and monitoring device according to a second embodiment of the present invention.

FIG. 3 is an electric motor protection and monitoring device according to a third embodiment of the present invention.

FIG. 4 is an electric motor protection and monitoring device according to a fourth embodiment of the present invention.

FIG. 5 is a conventional protection and monitoring device for an electric motor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 motor 2 rotor 3, 21, 32 conductor 4 thermocouple 5 illuminant 6 measuring circuit 7 conversion circuit 8 protection / monitoring circuit 10 thermolabel 11 optical fiber 22 correction circuit 23 rotation speed detector 31 temperature measuring resistor

Claims (4)

[Claims] 1. A protection and monitoring device for an electric motor having a rotor and a stator, wherein the thermosensor is installed on the rotor and has an electromotive force that changes according to a temperature value. A light-emitting body that is arranged at the center of the shaft end on the non-load side of the rotor and changes the amount of luminance based on the magnitude of the electromotive force; and converts the amount of luminance into a temperature value to detect the temperature state of the rotor. A protection circuit for the electric motor, comprising: 2. A protection and monitoring device for a motor having a rotor and a stator, wherein the thermo label is installed on the rotor and changes color depending on a temperature value. An optical fiber attached to the inside of the rotor that detects from the center of the shaft end on the load side, and a measurement circuit that converts the color of the thermo label into a temperature value and detects the temperature state of the rotor. A protection monitoring device for a motor. 3. A protection and monitoring device for an electric motor having a rotor and a stator, wherein the conductor is mounted around the rotor at a position orthogonal to a magnetic flux formed by the stator, and the conductor is mounted on the conductor. A resistor that changes to a predetermined resistance according to temperature; connected to the conductor, located at the center of the shaft end on the non-load side of the rotor, and the rotor or the conductor is connected to the conductor or resistor during rotation. An electric motor comprising: a light-emitting body whose luminance amount changes according to the magnitude of the generated electromotive force; and a measurement circuit that converts the luminance amount into a temperature value and detects a temperature state of the rotor. Protection monitoring equipment. 4. An apparatus according to claim 1, further comprising an alarm system for issuing an alarm based on a result of the temperature value in said measuring circuit.