JP2665855B2 - Life detection method of heater for electric furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting the life of an electric furnace heater, which detects the life of the electric furnace heater from a change in resistance.

[0002]

2. Description of the Related Art A heater for an electric furnace is designed and manufactured by selecting the type, length, and thickness conditions for each furnace based on the size and type of the furnace. The heater gradually wears and deteriorates due to the use of the electric furnace, and eventually breaks.

[0003]

Conventionally, there is no method for detecting the life of an electric furnace heater of this kind, and a user knows the end of the life of the heater or disconnection by the occurrence of a defect such as the temperature does not actually rise. This is extremely inconvenient. In addition, as described above, since this type of heater differs for each furnace and is not easily available, the user always has a spare heater as a measure against disconnection. You have to wait and change.

It is extremely uneconomical to always have a spare heater, and furthermore, there is a problem that a storage space for the spare heater is required. In addition, if the heater is ordered after the disconnection, it takes a long time to obtain and replace the heater, during which time the electric furnace cannot be operated, the operating efficiency is reduced, and the productivity is reduced. SUMMARY OF THE INVENTION It is an object of the present invention to automatically detect the life of a heater for an electric furnace and to make an end-of-life notice, disconnection prediction, and the like.

[0005]

In order to achieve the above object, in the method for detecting the life of an electric furnace heater according to the present invention, in the case of claim 1, a voltage and a current of the electric furnace heater are detected and a cycle is detected. Divides the voltage detection signal by the current detection signal, stores the initial divided value of the power supply as the initial value, compares the initial value with the divided value of each cycle, and detects the life of the heater, When the comparison result reaches a predetermined value, the end of life is notified.

In the case of claim 2, the voltage and current of the electric furnace heater are detected, and the voltage detection signal is periodically divided by the current detection signal, and the divided value at the beginning of power supply is used as an initial value. The heater life is detected by comparing the initial value with the divided value in each cycle, and the disconnection time is predicted from the comparison result.

Further, in the case of the third aspect, the voltage and current of the electric furnace heater are detected, the voltage detection signal is periodically divided by the current detection signal, and the divided value at the beginning of power supply is used as the initial value. The stored value is compared with the initial value and the divided value in each cycle to detect the life of the heater. When the comparison result reaches a first predetermined value, the end of life is notified, and the comparison result indicates the second predetermined value. Notify when the value has reached the disconnection.

[0008]

In the method for detecting the life of an electric furnace heater according to the present invention having the above-described configuration, first, in the configuration of the first aspect, the detection signal of the heater voltage is divided by the detection signal of the current. , The resistance value of the heater is obtained, the initial resistance value of the power supply is stored as an initial value, and the life is automatically detected by comparing the initial value with the resistance value of each cycle. The end is announced. Claim 2
In the configuration (1), the life is automatically detected in the same manner as in the first aspect, and the disconnection time is predicted by this detection.

Further, in the configuration of the third aspect, the life is automatically detected in the same manner as in the first and second aspects, and the end of the life is notified when the resistance value reaches the first predetermined value. When the heater further deteriorates and the resistance value reaches a second predetermined value, a disconnection is notified and a so-called two-stage alarm is issued.

[0010]

An embodiment will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an AC power supply, and 2 denotes a power supply control unit provided between the AC power supply 1 and the electric furnace heater 3, and is configured by an anti-parallel connection circuit of thyristors 2 a and 2 b. Reference numeral 4 denotes a drive control circuit for the thyristors 2a and 2b.

5 is a voltage detector for detecting the power supply voltage of the heater 3, 6 is a current detector for detecting the power supply current of the heater 3,
Reference numeral 7 denotes a life detection processing unit having a microcomputer configuration, which includes an A / D converter 8, a divider 9, a controller 10 formed by an ALU, a memory 11, a timer 12, and a comparator 13. Reference numeral 14 denotes an alarm such as an indicator light or a buzzer.

When an AC power supply 1 is turned on by operating a switch or the like, the power supply 1 is supplied to a heater 3 via a power supply control unit 2.
Power is supplied to At this time, the thyristor 2 of the power supply control unit 2
a and 2b are driven by the control of the drive control circuit 4 based on the temperature setting and the like.

Then, the voltage and current of the heater 3 are constantly detected by the detectors 5 and 6, and the detector 5 and the converter 6
Are supplied with voltage and current detection signals, and are converted into digital signals. Further, the voltage and current detection signals of the converter 8 are supplied to a divider 9, which divides the voltage detection signal by the current detection signal to form a signal of the resistance value of the heater 3. Is done.

On the other hand, when the power is turned on, the timer 12 is started, and after the elapse of a transient time required for stabilizing the temperature in the electric furnace, the timer 12 outputs the first detection command to the controller 10. Based on this first detection command, the controller 10 takes in the output signal of the divider 9 as a resistance value at the beginning of power supply, that is, an initial value, and writes the initial value in the memory 11 and stores it.

After the output of the first detection command, the timer 12 outputs the detection command to the controller 10 at a set cycle.
And the resistance value (current value) at that time based on the output signal of the divider 9 is supplied to the comparator 13.

With this supply, the comparator 13 compares the initial value with the current value, and determines the magnitude of the current value with respect to the initial value from, for example, a difference or a ratio between the two values. When the resistance value of the heater 3 increases due to wear and deterioration of the heater 3 and the current value reaches a predetermined value, the comparator 13 supplies a display signal and a drive signal for a life end notice of the heater 3 to the alarm 14.

Incidentally, the predetermined value is set so that the disconnection of the heater 3 is detected in advance with a time margin such as a heater obtaining period. Therefore, the annunciator 14 notifies the end of the service life by the display signal and the drive signal before the heater 3 is actually disconnected by a lighting display and a buzzer sound output.

The user places an order for a replacement heater based on the advance notice of the alarm 14, and continues to operate the electric furnace using the current heater 3 until the heater is obtained, thereby making various operations. The most efficient operation of the electric furnace is possible.

In the case where the notification based on the life detection is performed more effectively, the predetermined value for the advance detection of the disconnection of the heater 3 is set to a first predetermined value. The value is set as a second predetermined value for disconnection notification, and both predetermined values are set in the comparator 13. Then, when the current value reaches the first predetermined value, the comparator 13 outputs the signal for the end-of-life notice to the annunciator 14.
When a predetermined value is reached, the comparator 13 outputs a display signal and a drive signal for disconnection notification to an alarm 14 or an alarm (not shown).

In this case, the alarm 14 is provided before the heater 3 is disconnected.
In addition to notifying the end of the service life, when the wear and deterioration of the heater 3 further progresses and reaches just before the actual disconnection, the disconnection is notified by the alarm 14 or the alarm, so-called 2
A step alarm is issued.

Further, various heater data such as the type, length and thickness of the heater 3 are stored in the memory 11, and the comparison result of the comparator 13 is taken into the controller 10, for example, and the controller 10 The remaining time until disconnection may be calculated by grasping the change tendency of the resistance value of the heater 3 and the like from the heater data, and the disconnection time may be predicted from the calculation result and displayed as a number on a display. In this case, since the disconnection time is specifically notified (displayed), reliability and the like are improved.

Since the prediction of the disconnection time is updated based on the comparison result in each cycle, an appropriate prediction display is performed even when the use conditions and the like change. In addition, an alarm 1
Of course, it may be used in combination with the notice of the end of life using 4 or the like and the disconnection notification.

The configuration and the like of each unit are not limited to the embodiment. For example, the thyristor 2a,
Instead of 2b, a triac, an inverse-parallel connection circuit of a thyristor and a diode, or an inverter in which a thyristor is connected to a rectifier of a diode bridge may be provided.

[0024]

Since the present invention is configured as described above, the following effects can be obtained. In the case of the configuration of claim 1, the resistance value of the heater 3 is obtained by dividing the detection signal of the voltage of the heater 3 by the detection signal of the current, and the resistance value at the beginning of power supply is stored as an initial value. The life of the heater 3 is automatically detected by comparison with the resistance value in each cycle, and when the resistance value reaches a predetermined value, the end of the life is predicted. Therefore, the life of the heater 3 is automatically detected and the heater 3 is detected in advance. The end of the service life of 3 can be known, a replacement heater can be ordered after the advance notice, and the replacement can be performed without waiting time, and the electric furnace can be operated efficiently without keeping a spare heater or stopping the operation. can do.

Further, in the case of the configuration of claim 2, claim 1
Since the life of the heater 3 is automatically detected and the disconnection time is predicted by this detection, the life of the heater 3 is automatically detected and the disconnection time is predicted to determine the disconnection time. Can be informed.

Further, in the case of the third aspect, the life of the heater 3 is automatically detected in the same manner as in the first and second aspects, and when the resistance value reaches the first predetermined value, the life is shortened. The end is forewarned, and if the heater is deteriorated and the resistance value reaches the second predetermined value, the disconnection is notified, so that a so-called two-stage alarm can be performed, and more effective notification can be performed than in the case of claim 1.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of a life detecting method of an electric furnace heater according to the present invention.

[Explanation of symbols]

 Reference Signs List 3 heater for electric furnace 5 voltage detector 6 current detector 7 life detection processing unit 8 A / D converter 9 divider 10 controller 11 memory 12 timer 13 comparator 14 alarm

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-239595 (JP, A) JP-A-2-100290 (JP, A) JP-A-62-249393 (JP, A) JP-A-61-249 35113 (JP, A) JP-A-61-2298 (JP, A) JP-A-52-1981 (JP, A) JP-A-52-28763 (JP, U) JP-B-41-7263 (JP, B1)

Claims (3)

(57) [Claims] 1. A voltage and a current of an electric furnace heater are detected,
The detection signal of the voltage is periodically divided by the detection signal of the current, a divided value at the beginning of power supply is stored as an initial value, and the initial value and a divided value of each cycle are compared, and the heater is compared with the initial value. A method for detecting the life of an electric furnace heater, comprising detecting a life and notifying the end of the life when a comparison result reaches a predetermined value. 2. Detecting the voltage and current of the electric furnace heater,
The detection signal of the voltage is periodically divided by the detection signal of the current, a divided value at the beginning of power supply is stored as an initial value, and the initial value and a divided value of each cycle are compared, and the heater is compared with the initial value. A method for detecting the life of an electric furnace heater, comprising detecting a life and predicting a disconnection time from a comparison result. 3. Detecting the voltage and current of the electric furnace heater,
The detection signal of the voltage is periodically divided by the detection signal of the current, a divided value at the beginning of power supply is stored as an initial value, and the initial value and a divided value of each cycle are compared, and the heater is compared with the initial value. A heater for an electric furnace, comprising detecting a service life, notifying the end of the service life when a comparison result reaches a first predetermined value, and notifying a disconnection when the comparison result reaches a second predetermined value. Life detection method.