JPH0526415B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an abnormality monitoring device that monitors abnormalities in monitored objects, such as motor windings and bearings, based on temperature.

[Technical Background of the Invention] Generally, in order to monitor abnormalities in motor windings, a signal that detects the winding temperature is processed by a computer, and if there is an abnormality as a result of this processing, an alarm is issued and at the same time a display device displays the details of the abnormality. There are some that display

Figure 1 is a block diagram showing the configuration of this type of conventional abnormality monitoring device.
convert it to an analog signal via
It is being imported into the CPU. Computer CPU receives input signal T _N
If there is an abnormality in the processing result, the alarm BZ will sound and the display will be activated.
Display abnormality details on CRT.

Figure 2 is a graph showing an example of winding temperature rise, with temperature on the vertical axis and time on the horizontal axis.
The computer CPU inputs the input signal T _N every check time Δt.
It is determined whether the temperature rise Tmax is the permissible limit value of the winding temperature, and furthermore, when the temperature rise is below the upper limit Tmax, a temperature gradient check is performed as an early abnormality detection of the winding temperature. The method of checking the temperature gradient is to calculate the deviation between the previous input signal T _N - ₁ , which is the temperature data at the previous check, and the input signal T _N , which is the temperature data at the current check, at each check time Δt. The deviation in temperature is calculated as the deviation in temperature gradient ΔT _N.

Figure 3 shows the computer used in conventional abnormality monitoring equipment.
This is a flowchart showing the processing contents of the CPU. It reads the input signal T _N , compares it with the temperature upper limit Tmax, and if T _N is larger than Tmax, it sounds the alarm BZ and at the same time displays the temperature upper limit on the display device CRT. Outputs a failure message. Further, if the input signal T _N is smaller than the upper temperature limit Tmax, the deviation from the previously checked temperature data T _{N -1} is calculated, and the calculation result is set as the temperature gradient ΔT _N. Next, ΔT _N is compared with the temperature gradient abnormal value ΔTmax, and the temperature gradient abnormal value △
If it is larger than Tmax, sound the alarm BZ,
Outputs a message indicating temperature gradient abnormality to the display device CRT. Further, if the temperature gradient ΔT _N is smaller than the temperature gradient abnormal value ΔTmax, the input signals ΔT _N are sequentially read and processed. Furthermore, the temperature upper limit which is the abnormality judgment value
Tmax and temperature gradient abnormal value ΔTmax are input into the computer CPU in advance.

[Problems with the background art] It is true that such conventional abnormality monitoring devices
Temperature upper limit Tmax and temperature gradient abnormality detection ΔTmax can be determined. However, in temperature gradient abnormality detection, the temperature gradient abnormal value ΔTmax is set to the maximum temperature rise value when the motor is operating normally, so depending on the operating state of the exercise machine, temperature gradient abnormality detection may not be possible and the temperature upper limit In some cases, an abnormality may be detected only after reaching this point. In other words, temperature rises in the motor windings are caused by cold starts, where the motor is started after it has stopped for a long time, hot starts, where the motor is restarted shortly after stopping, and rolling mill motors, which are caused by acceleration/deceleration and regular overload operation (200 % overload for 1 minute, etc.)
The temperature rise value of the exercise machine winding with respect to the check time Δt differs depending on each operating condition. Therefore, if the temperature gradient abnormal value ΔTmax is not set as the maximum temperature increase value during normal operation, a false alarm will be issued. For this reason, if an abnormality occurs during light load operation and the temperature of the winding rises below the temperature gradient abnormal value ΔTmax, there is a drawback that the abnormality cannot be detected due to the temperature gradient abnormality and is detected only after the temperature reaches the upper limit Tmax. . For equipment that stops the motor at the upper temperature limit Tmax, a sudden stop during operation will have a negative impact on the load and related equipment. For example, in rolling equipment, if the rolling equipment is stopped during rolling, the rolled material becomes defective, and in heating furnace blowers and the like, the temperature inside the furnace increases, which has an adverse effect. Furthermore, if the motor is not stopped at the upper temperature limit Tmax, there will be effects such as burnout of the windings and shortened lifespan. For this reason, temperature gradient check monitoring is performed as one of the purposes for detecting abnormalities at an early stage.

[Object of the invention] The present invention has been made in consideration of the above circumstances, and
An object of the present invention is to provide an abnormality monitoring device that can detect an abnormality in an electric motor, which is an object to be monitored, at an early stage, and can take countermeasures at an early stage before the temperature reaches an allowable limit.

[Summary of the Invention] In order to achieve the above object, the abnormality monitoring device of the present invention includes first and second temperature detectors that respectively detect the temperatures of at least two electric motors operated under the same conditions; Each time the input signals from the first and second temperature detectors are checked, the temperature change is calculated, each deviation is calculated, and the deviation value is compared with a judgment value to determine whether it is normal or abnormal. ,
It is equipped with a computer that outputs an alarm signal and an abnormal signal when an abnormality is determined, an alarm device that issues an alarm based on the alarm signal from the computer, and a device that displays the details of the abnormality based on the abnormal signal from the computer. It consists of

[Embodiments of the Invention] The present invention will be described below with reference to the drawings, and FIG. 4 is a block diagram showing one embodiment of the present invention. Here, an electric motor of a rolling mill is taken as an example of the object to be monitored, but the present invention is not limited to this, and can be applied to cases where there are two or more objects to be monitored whose temperature increases approximately. Generally, a rolling mill has two electric motors, one for the upper roll and one for the lower roll.
The first temperature detector RTD is installed on the motor winding for the upper roll.
A second temperature detector RTD2 is provided on the lower roll motor winding, and a first signal converter RTD2 is provided on the motor winding for the lower roll.
Input signal ΔT _N via TRD1 and second signal converter
The second input signal T _M via TRD2 is taken into the computer CPU. The computer CPU performs abnormality judgment processing based on the input signals T _N and T _M , and if there is an abnormality in the processing result, it sounds the alarm BZ and displays the display device.
Display abnormality details on CRT.

The first signal converter TRD1 and the second signal converter TRD2 are connected to the first temperature detector RTD1 and the second temperature detector RTD1.
It converts the data of the temperature detector RTD2 into a digital signal that can be interpreted by the computer CPU.

Figure 5 shows an example of winding temperature rise, with temperature plotted on the vertical axis.
This graph shows time on the horizontal axis, and the computer CPU outputs the first input signal T _N at every check time Δt.
Alternatively, it is determined whether the second input signal T _M is at the temperature upper limit Tmax, which is the permissible limit value of the winding temperature, and if it is below the temperature upper limit Tmax, a temperature gradient check is performed as an early abnormality detection of the winding temperature. . The method of checking the temperature gradient is to input the previous first input signal T _N - ₁ and the previous second input signal T _M - ₁ , which are the temperature data from the previous check, at every check time Δt, and the second input signal, which is the temperature data from the current check. 1 input signal
T _N and the deviation of the second input signal T _M are respectively calculated, and the deviation of the first winding temperature is determined by the first temperature gradient ΔT _N ,
The deviation of the second winding temperature is calculated as the second temperature gradient ΔT _M.

FIG. 6 is a flowchart showing an example of the processing contents of the computer CPU in the abnormality monitoring device _according to the present invention.
When compared with the temperature upper limit Tmax, if T _N is larger than Tmax, the alarm BZ is sounded, and at the same time a temperature upper limit failure message is output to the display device CRT, and the next second input signal T _M is read. If the input signal T _N is smaller than the temperature upper limit Tmax, the deviation from the previously checked temperature data T _{N -1} is calculated, and the calculation effect is set to the first temperature gradient ΔT _N. Next, the first temperature gradient ΔT _N is compared with the temperature gradient abnormal value ΔTmax, and if it is larger than the temperature gradient abnormal value ΔTmax, the alarm BZ
sounds, outputs a temperature gradient abnormality message to the display CRT, and reads the next second input signal T _M. Further, if ΔT _N is smaller than ΔTmax, the second input signal Tn is read, and thereafter the second input signal Tn is processed in the same manner as the first input signal T _N , and T _N or T _M are sequentially read. Note that the temperature upper limit Tmax and temperature gradient abnormal value ΔTmax, which are abnormality determination values, are input into the computer CPU in advance.

As mentioned above, the abnormality monitoring device of this embodiment is
first and second temperature detectors RTD1 and RTDG2 that respectively detect the temperatures of at least two electric motors operated under the same conditions;
first and second signal converters TRD1 and TRD2 converting output signals from temperature detectors RTD1 and RTD2 into digital signals, and input signals T _N and TRD2 from the first and second signal converters TRD1 and TRD2. For each check input of T _M , the temperature change is calculated and each deviation is calculated. This deviation value is compared with the judgment value to determine whether it is normal or abnormal. If it is determined to be abnormal, an alarm signal and abnormality are issued. A computer CPU that outputs a signal, an alarm BZ that issues an alarm based on the alarm signal from the computer CPU,
It consists of a display device CRT that displays the details of the abnormality based on the abnormality signal from the computer CPU.

Therefore, it is possible to detect an abnormality in the motor, which is the object to be monitored, at an early stage, and to take countermeasures at an early stage before the temperature reaches the permissible limit. That is, it is possible to detect abnormalities including those related to the mechanical auxiliary equipment of the electric motor that is the object to be monitored.

Specifically, this includes a comparison of the winding temperatures of directly connected motors, the temperature of the left and right bearings of the motor, and the internal temperature of the drive device operated under the same conditions. That is, a comparison of the motor winding temperatures can detect an abnormality in the cooling air, a motor bearing temperature can detect an abnormality in the bearing oil supply, and a temperature inside the panel of the drive device can detect an abnormality in the cooling device.

Next, referring to the flowcharts of FIGS. 7 and 8, the computer in the abnormality monitoring device of the present invention will be explained.
Another example of the processing content of the CPU will be explained. In the figure, the same contents as in FIG. 6 indicate the same elements, and the difference from FIG. 6 is that the functions of FIG. 8 are added to the parts surrounded by dotted lines. In the present invention, as mentioned above, it goes without saying that two or more objects to be monitored are required to be operated under the same conditions, and there is a condition that the temperature rises are similar to each other during normal operation. There are electric motors for the upper roll and lower roll of the machine, and because these are large electric motors, temperature abnormalities are generally monitored. The signal from one temperature sensor of the monitored object is the first input signal T _N , and the signal from the other temperature sensor is the second input signal T N .
Given an input signal T _M , the computer CPU reads T _N and T _M at every check time Δt.

FIG. 8 shows additional functions of the processing content of the computer CPU, and related functions will be explained from FIG. 7.

First, read the first input signal T _N and set the temperature upper limit.
Compared to Tmax, when T _N is smaller than Tmax,
The deviation between T _N and the previous first input signal T _{N -1} read during the previous check time Δt is calculated, and the result is set as the first temperature gradient ΔT _N. Next, if ΔT _N is smaller than the pre-input temperature gradient abnormal value ΔTmax, the second input signal T _M is read, and if T _M is smaller than the temperature upper limit Tmax, the previous second input signal T read during the previous check time Δt. The deviation from _M − ₁ is calculated, and the calculation result is set as the second temperature gradient ΔT _M. Next, if ΔT _M is smaller than the temperature gradient abnormal value ΔTmax, go to FIG. 8 and calculate the deviation between the first temperature gradient ΔT _N and the second temperature gradient ΔT _M , and use the calculation result as the temperature gradient deviation value ΔT. . On the other hand, as a condition for adopting the present invention, ΔT _N and ΔT _M are subject to approximate temperature rise, and the error range of ΔT _N and ΔT _M when the motor is operating normally is calculated in advance as the slope abnormality judgment value ΔT _S. It is input to the CPU. This ΔT _S is compared with the temperature gradient deviation value ΔT, and if ΔT is larger than ΔT _S , it is determined that the temperature gradient is abnormal. If ΔT is smaller than ΔT _S , compare the slope abnormality judgment value ΔT _S to −ΔT _S on the negative side, −
If it is smaller than _ΔTS , it is determined that there is a second temperature gradient abnormality and proceeding. Also, when ΔT is greater than −ΔT _S , go to , then the next input signal T _N from FIG.
Or, if T _M exists, read T _N again every check time Δt. In this way, the input signal T _N
and repeat until T _M is exhausted.

According to the processing contents of the computer CPU shown in FIGS. 7 and 8 described above, for example, in a rolling mill electric motor, the abnormal value of the temperature gradient is set to the maximum temperature rise value for each check time in the normal operating state. Temperature gradient abnormalities can be detected even earlier. Specifically, in Fig. 6, the temperature gradient abnormal value was 5 to 10°C with a check time of 1 second, but in Figs. 7 and 8, it can be detected at 2 to 3°C. Even if an abnormality occurs, it can be detected earlier.

This allows early measures such as motor load adjustment to be taken, thereby reducing the impact on equipment.

[Effects of the Invention] As explained above, according to the present invention, first and second temperature detectors each detect the temperature of at least two electric motors operated under the same conditions;
Each time the input signals from the first and second temperature detectors are checked, the temperature change is calculated, each deviation is calculated, and the deviation value is compared with a judgment value to determine whether it is normal or abnormal. , a computer that outputs an alarm signal and an abnormal signal when an abnormality is determined;
The system is equipped with an alarm device that issues an alarm based on the alarm signal from the computer, and a display device that displays the details of the abnormality based on the abnormality signal from the computer.
It is possible to provide an abnormality monitoring device that can detect an abnormality in an electric motor, which is a monitored object, at an early stage and take countermeasures at an early stage before the temperature reaches an allowable limit temperature.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of an example of a conventional abnormality monitoring device, Fig. 2 is a graph showing temperature rise to explain the operation of the device in Fig. 1, and Fig. 3 is the processing of the computer of the conventional device. Flowchart showing the contents, FIG. 4 is a block diagram showing the configuration of an embodiment of the abnormality monitoring device according to the present invention, FIG. 5 is a graph showing temperature rise to explain the operation of the embodiment, and FIG. 6 7 is a flowchart showing a different example of the processing contents of the computer of the abnormality monitoring device according to the present invention, and FIG. 8 is a flowchart specifically showing a part of FIG. 7. RTD, RTD1, RTD2...Temperature detector,
TRD, TRD1, TRD2...Signal converter, CPU
…Calculator, BZ…Alarm, CRT…Display device, T _N , T _M …Input signal, T _N-1 , T _M-1 …Previous input signal, ΔT _N , ΔT _M …Temperature gradient , Δt...Check time, Tmax, ΔTmax, _ΔTS ...Abnormality judgment value, ΔT...Temperature gradient deviation.

Claims (1)

[Claims] 1. First and second temperature detectors (RTD1 and RTD2) that respectively detect the temperatures of at least two electric motors operated under the same conditions; and the first and second temperature detectors. Check the input signals (T _N and T _M ) from RTD1 and RTD2, read the temperature change for each check input, calculate the deviation of each, and compare the deviation value with the judgment value to determine whether it is normal or abnormal. A computer that determines the situation and outputs an alarm signal and an abnormal signal if it is determined to be abnormal.
It is characterized by comprising: a CPU; an alarm device BZ that issues an alarm based on an alarm signal from the computer CPU; and a display device CRT that displays abnormality details based on the abnormality signal from the computer CPU. Abnormality monitoring device.