JPS5887425A - Induction type level gage - Google Patents

Abstract

PURPOSE:To detect abnormality of a level gage quickly by detecting the level of an exciting input signal to be fed to an excitation coil. CONSTITUTION:A constant current source 7 feeds a constant current to an excitation coil 2 of a level gage. A voltmeter 8 is connected to a detection coil 3 of the level meter to measure the water level. A voltage e developed across a resistor 16 is applied to an AC-DC converter 7. The converter 7 converts the voltage e into a d.c. voltage to be provided to a comparator/discriminator 18. The discriminator 18 compares the voltage (e) inputted from the converter 17 with the referenc voltage and provides the results to an alarm display 21 through a logic circuit 20. When any abnormality in the level gage causes a change in the exciting current, the display 21 works.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inductive liquid level needle suitable for measuring the level of a conductive liquid such as liquid sodium used as a coolant in a fast breeder reactor. In particular, it relates to means for detecting abnormalities in the liquid level needle body.

Technical Background of the Invention: The conductive liquid level needle has a relatively simple structure and is difficult to maintain, so it is used as a liquid level needle to measure the level of liquid sodium used as a coolant in fast breeder reactors, for example. It is widely used.

FIG. 1 is a diagram showing the structure of a conventionally known continuous guide type intermittent needle. As shown in the 1st ml, the main body of this liquid level needle has a coil holder 1, a measuring coil 2 and a detection coil 1 wound around it.

The above-mentioned coil 1.3 is covered and stored in a storage tube 4, and is placed in a guide tube C which is inserted downwardly into the liquid sodium chamber IIl from the upper wall thereof. When measuring the liquid level, an alternating constant current is applied to the excitation coil 1 from a constant current source r at a constant number of cycles. is supplied to the detection coil 3 and the voltage V applied to the detection coil 3 is kept constant using the voltmeter C], the liquid level L is determined *! This is required from the perspective of the Cabinet.

The 211th is the sodium liquid level L and the detection coil 1.
As is clear from this diagram, within the liquid level measurement range I, the liquid level L
and the voltage V have a linear function relationship. Therefore, within the above range, the liquid level L can be determined accurately and continuously based on the induced voltage V.

FIG. 3 is a diagram showing the structure of a conventionally known fixed type haze guide liquid level needle. As shown in the third cabinet, the main body of this liquid seal meter includes a coil bobbin 1, an excitation coil 2, and a pair of detection coils JA.

IB and these coils 2 and JA.

jB is covered and protected with a protection tube 4, and is inserted into a guide tube C which is inserted into a liquid sodium container 5 in a downward direction. In other words, the basic structure of the main body of this liquid level needle is almost the same as that shown in FIG. They are different in that they are set up. When measuring the liquid level, an alternating constant current with a constant number of cycles is supplied from the constant current W1 to the excitation coil 1, and the detection coil 1
The voltage induced by 31 people is amplified by amplifiers 9 and pm, respectively.

Each amplified voltage is passed through a filter 10m, 1-1 to remove noise components, that is, the detection voltage V
A, Ml is the differential voltage V by the differential amplification flall
After C is taken out, it is converted into a liquid level display signal by the logic circuit II and applied to the liquid level indicator 14. Therefore, the liquid level is displayed by the display 14 based on the relationship shown in FIG. 114.

FIG. 4 is a diagram showing the relationship between the detection voltages Vm, vm corresponding to the liquid level L and the output voltage VC of the differential amplifier @SZ. As is clear from this fourth Ill, the output voltage V of the differential amplifier 12, which is the difference between the two detection voltages Vm and vB.
C takes on its maximum value when the 111 level reaches the level L1 where the excitation coil I reaches the center position. Therefore, when the above maximum value is detected, whether the liquid level is at the fixed liquid level Ll or not is determined whether the inductive liquid seal meter is a continuous type or a fixed type as described above. Regardless, it is necessary to stably supply an alternating light current of a constant frequency to the exciting coil I. In particular, in the continuous type, the absolute value of the induced voltage is directly used as the detection voltage for measuring the liquid level, so if the electric fall is not kept at a constant value, it will immediately become a constant liquid level difference. . Therefore, in the past, in order to always supply a constant level of alternating current,
Using an extremely stable constant current circuit as a constant current source,
Even if the impedance of the excitation coil 2 fluctuates due to changes in the sodium temperature, etc., the electric current fILt1 is automatically adjusted and kept at a constant value. However, the conventional IIIi needle lacks a means for checking whether the excitation current (by the constant current circuit) is actually maintained at a constant value with good integration. For this reason, for example, in the case where the excitation coil 1 is disconnected, not only is it impossible to measure the actual liquid level L, but there is also a risk that the EA meter width may be incorrect.

Particularly when there is a large change in the liquid level, the normal measurement value itself changes significantly, so it is essentially difficult to accurately distinguish whether or not the measurement is erroneous.

Purpose of the present invention The purpose of the present invention is to detect any abnormality in the liquid level needle itself, even if the normal needle value itself changes significantly due to a change in the measured surface level or a large disturbance. When an abnormality occurs, the meeting can promptly and accurately know about the abnormality.
To provide an extremely reliable guide type liquid level needle without the risk of continuing to hold an incorrect meter for a long time.

The present invention is constructed as follows in order to achieve the above object. That is, at least one of an excitation input signal such as an excitation current given to the excitation coil of the main body of the -conduction *i*w meter, or a detection output signal of the trout supervoltage cape detected by the detection coil of the main body.

For example, the signal is extracted by a signal extraction means consisting of a detection resistor or the like. Then, by comparing the level of Jin's signal with the reference level using a comparison judge, it is possible to
It is determined whether or not it is within s, and if it is outside the standard range, the meeting sends out an abnormal signal from the comparison/judgment device. Next, this abnormal signal is processed by an alarm signal forming circuit consisting of, for example, a logic circuit, thereby forming an alarm signal corresponding to the abnormal signal. Then, an alarm based on this alarm signal is emitted by an alarm indicator equipped with a display function (therefore, an alarm is issued).In this way, an abnormality such as a coil breakage occurs in the liquid level needle body, and the signal level falls within a specified range. If the condition is exceeded, the alarm indicator will immediately issue a predetermined alarm.

Embodiment of the Invention FIG. 5 is a diagram showing an embodiment in which the present invention is applied to a continuous induction type liquid level needle, and 41 is a block diagram showing only the electrical system extracted. As shown in FIG. 5, a current detection resistor 1# is inserted and connected to the electric line 15 running between the constant current source 1 and the excitation coil 1. The voltage generated across this resistor Ig is applied to a DC-DC converter 111F. The converter 11 converts the voltage into a DC voltage and applies it to the comparison judgment -11. Comparison/judgment device 1# compares the DC voltage input from converter 11 with the reference voltage applied to terminal 1#, and determines whether or not it is within a specified range. The above normal voltage range means that when the liquid level needle body is normal, the resistor IC
The reference voltage is the voltage that is used to set the first level and lower limit level of the above-mentioned tolerance II@I as a matching value. Thus, when the comparison/judgment unit 1g determines that the DC voltage from the converter 11 is outside the specified range, it sends an abnormality signal to the logic circuit 2# as a writing signal forming circuit. The logic circuit 1- performs a predetermined logical operation on the abnormality signal from the comparator 11, outputs an alarm signal corresponding to the abnormality signal, and supplies this to the alarm indicator 1-. The alarm display 11 is, for example, a shaded tube display (JaT).
C-o! A predetermined alarm based on the alarm signal sent from the logic circuit zo is displayed as an image from the display. The parts other than those mentioned above are the same as the conventional one, so the same reference numerals are given to the Oka part and m@ is omitted.

In the wavefront meter #C of the present invention configured as described above, when the liquid level needle body is normal, a constant level of excitation current flows through the resistor 1, so that the resistor 16 has approximately A certain voltage drop occurs.

This voltage / is input to the ratio INN regulator IJ through the converter 11, but since the level of voltage / at this time is within the specified range sie as shown in Fig. 6, the comparator 1 There is no signal from #. Therefore, no warning is issued.

Now, something is wrong with the liquid level needle itself.

Suppose that a fluctuation occurs in the excitation voltage #lI. Then, a voltage is generated across the resistor ll1- which includes a fluctuation component corresponding to the above-mentioned abnormality. This voltage O is converted into a DC voltage by the converter 11 and inputted to the comparison/judgment device 18. Since fluctuating components are present individually or simultaneously, these fluctuating components x, y, and z are detected as abnormal signals and sent to logic circuit 1#.

When the above abnormal signal is input to logic path I#.

This abnormal signal is processed and processed, for example, as shown in Figure 6! eF
*It becomes a square wave alarm signal like I.

When the above alarm signal is sent to the alarm display 11.

If the alarm display @xi is activated and an abnormality occurs in the liquid temperature needle body, the user can immediately know that an abnormality has occurred in the liquid level needle body by checking the alarm display contents of the alarm display 21.

Incidentally, as a cause of the generation of the X 411R dynamic component of No. 6Ia, flue accident III due to deterioration of the insulation of the detection coil is considered to be the cause of the 411R dynamic component of the 6th Ia. Happy SS again! A possible cause of the II fluctuation component is, for example, a temporary contact failure related to the connector. II et al. 6th garden 2
A possible cause of this fluctuation component is a new line in the excitation coil. Therefore, by displaying an alarm on the alarm display 11 in accordance with the output signal waveform (pulse width, etc.) of the logic amz-, the above-mentioned cause can be solved.

Next, another embodiment shown in FIG. 7 will be explained.

FIG. 11a is a diagram showing an embodiment in which the present invention is applied to a fixed type guide type liquid level needle, and, like FIG. 6, is a block diagram showing only the electrical system of the terminal. As shown in FIG.
11 converters.

A pair of comparison/judgment devices 1#A are provided at the output end of the 11th emperor.

Connect the signal input terminal of 711 to each comparison/judgment device 1#, 1
A predetermined reference voltage is applied to each of the 19 reference voltage input terminals #■ and 1#n. The above reference voltages are the maximum and minimum values of the detection voltages (voltages corresponding to Vm and VB2 in Figure 4) output from each converter 11 and 11 when the liquid level needle body is normal. This is the voltage used as the "threshold". The output signals of the comparison/judgment devices 1s and JIIB are sent to the logic circuits 20 and 20, respectively, and the logic circuits Hj
The output signals of O person and 203, that is, the alarm signals, are alarm indications @11, respectively.

Sent to 11S.

Thus, in this actual case, even if the voltage detected by the detection coil 3,
Detection coil 1 has become abnormally large due to contact with coil 1 and detection coil 1 and 1), and detection coil 3 has become abnormally large.

If the abnormality becomes abnormally small due to the breakup of Jl, an alarm is displayed on the alarm displays 11jjA and 11m, as in the embodiment of Ill where the abnormality is interrupted.

Therefore, it goes without saying that abnormalities in the detection coils 3m and 1m, as well as electric
The abnormalities that occurred during the am from ay to the transfer @11m and ZJI.

Since the MU C-OC conversion@13 MU, 111 is used as a honeycomb exchanger for abnormality detection, there is no need to newly provide a MU C-DCII exchange amount, and the configuration is simplified accordingly.

Note that the present invention is not limited to the two embodiments described above. For example, as a signal extraction means, in the first embodiment, a means for extracting the lll1llk current that is passed through the wI magnetic coil I as a voltage drop that occurs in the resistor IC is shown, but in place of the resistor 1#, Other impedance elements may be used alone or in combination. In short, any means that can accurately extract and meet the excitation input signal is sufficient. Similarly, in the second embodiment, the outputs of the C-DC converters 11 and 11m are converted to the ratio I12.
Although we have shown a method for extracting signals by guiding the signals to the detection coils HA and 11m, it is also possible to insert a resistor or the like in the detection circuit connected to the detection coils HA and IB, and detect the voltage across the coils. Voltage/As Comparison Judgment Machine II, Jr.
It is also possible to input the information to l. In short, any means that can accurately extract the detection output signal may be used.

Further, in the first embodiment, the case where the excitation input signal is extracted is illustrated, and in the second embodiment, the case where the detection output signal is extracted is illustrated.

If necessary, the above-mentioned excitation input signal extraction means and detection output signal extraction means may be provided simultaneously for one guiding liquid level needle body.

Furthermore, in the above embodiment, a logic circuit that converts the waveform into a simple rectangular wave was used as the alarm signal forming circuit, but the signal after the waveform conversion as described above is further subjected to logical operations to determine the type of abnormality. A specific alarm signal clearly indicating the type may be generated and provided to the alarm display.

Further, in the above embodiment, C-o! is used as the alarm! Although an alarm indicator such as a display is shown, other alarm means such as an alarm lamp or a buzzer may be used alone or in combination with an indicator, etc.@Effects of the Invention According to the present invention, If the level of the excitation input signal such as the excitation current supplied to the am coil or the level of the detection output signal such as the induced voltage detected by the detection coil deviates from the specified range, a warning lamp or CLLT indicator will be displayed. amount is activated and an alarm is issued. Therefore, even if
Even in cases where the change in the liquid level is so large that the normal measurement value itself does not match the normal measurement value, if any abnormality occurs in the liquid level needle body, the Association will promptly and accurately correct the abnormality. I'm excited about what I know.

There is no fear that erroneous measurements will continue for a long time, and an extremely reliable guide type liquid level needle can be provided.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of a conventional continuous induction type liquid level needle, Fig. 2 is a characteristic diagram showing the relationship between liquid level L and induced voltage V in the liquid level needle shown in Fig. 1, and Fig. 3 is a diagram showing the relationship between liquid level L and induced voltage V in the liquid level needle shown in Fig. The figure shows a conventional fixed type
FIG. 4 is a diagram showing the structure of the liquid level needle shown in FIG. 3, and a characteristic diagram showing the relationship between the liquid level L in the liquid level needle shown in FIG. FIG. 5 is a block diagram showing the configuration of an electrical system of an embodiment in which the present invention is applied to a continuous induction type liquid level needle. FIG. 6 is a waveform diagram for explaining the operation of the same embodiment, and FIG. 7 is a block diagram showing the configuration of an electrical system of another embodiment in which the present invention is applied to a fixed type haze-conducting liquid level needle. DESCRIPTION OF SYMBOLS 1... Coil bobbin, 2... Excitation coil, 3 and jA, jl... Detection coil, 4... Bamboo shoots, 5...
- Sodium container, 6... guide tube, 1... constant current source. -, Na voltage needle, #A, III...Amplifier, 1 #A
, Jo layer...filter, 11m, 11m...mC
-0C converter, J j-...Differential amplifier I11, IJ...
・Logic-Route. 14--Liquid level indicator, 1--Electric circuit, 1--Resistor for current detection, 11--AC-DC converter, 1#. Quantity, 1m, 1# frame. 1#B... Reference voltage input terminal, xe, soA. ROB... logic circuit, xx, srm, 11 layers.
...Alarm indicator. Applicant's agent Patent attorney Liao Suzu Jiang Wu Figure 2 Meri v Shihele (L) Figure 3 Figure 4Ii ItJL Hele (L) Figure 51I1 Figure 6

Claims (1)

[Claims] (1: Signal extraction means for extracting an excitation input signal applied to the inductive liquid level needle body and the excitation coil of the body and/or a detection output signal detected by the detection coil of the body) Then, by comparing the level of the signal extracted by this signal extraction means with the reference level, it can be determined whether the signal is within the standard or not. A comparative signal transmitter that sends out an abnormal signal, a signal generator 4# formation path that forms an alarm signal according to the abnormal signal (by processing the abnormal signal from the comparative signal), and this path. A one-conductor type liquid gauge that is characterized by the fact that it has the ability to issue alarms based on alarm signals that are exclusively formed in the system. (2) The compensation 4# formation HII performs logical operations on the abnormality signal to generate a special electric alarm signal according to the type of abnormality. Claim No. 1 (1: One conductive liquid level needle as described in Clause 1). (3) The alarm amount is an alarm indicator having a function of displaying the content of the alarm Inductive liquid level needle.