JPS63106485A - Detector for operation of solenoid valve - Google Patents

Abstract

PURPOSE:To comfirm the operation of a solenoid valve during operation of a plant surely and instantaneously by converting ON/OFF of a power source for opening/closing the solenoid valve to ON/OFF at a zero potential cross point. CONSTITUTION:A converting means 57 is provided for converting ON/OFF of a power source for opening/closing solenoid valves 5, 6 to ON/OFF at a zero potential cross point. a resonance circuit is formed in connection of a solenoid coil to a capacitor 53 in parallel. The time, from the time when a power source is turned off to the time when a voltage or current resonated in a resonance circuit is turned off at the zero potential point by a converting means, is measured and is compared with the predetermined time during normal operation of the solenoid valve through a digital comparator 60. And, whether the solenoid valve is normal or abnormal is judged through an OR judgement/ display circuit 61.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to the control of solenoid valves, and in particular, to the control of solenoid valves in order to improve the safety and availability of various plants. It also relates to an operation detection device for a solenoid valve, which can also be confirmed.

(Prior art) Solenoid valves for important air-operated valves used in systems that operate only in the event of a plant abnormality and shut down the plant, such as emergency shutdown systems in nuclear power plants, are generally duplicated and constantly energized. The system is designed to prevent unnecessary plant shutdowns and ensure reliable operation in the event of an abnormality.

It is important to check the opening and closing of such solenoid valves to confirm their health even during plant operation, but if duplicated solenoid valves are operated at the same time, the plant may stop. Therefore, we are operating one valve at a time, but currently it is not possible to confirm that the solenoid valves are actually operating.

One way to check the operation of a solenoid valve is to install a limit switch, but this method is not used because the valve body is small and it is difficult to install, and there are a large number of valves. is the current situation. There are also methods that use acoustic sensors, but they have problems such as S/N ratio and reliability.

On the other hand, Japanese Patent Publication No. 59-12159 describes the following control device for a solenoid valve.

Alternating current is always supplied to the solenoid of the solenoid valve, and the movable iron piece is attracted into the solenoid. In order to check the operation of the solenoid valve in this state, when the current is stopped,
After a while, the movable iron piece is released from inside the solenoid.

When the current starts to flow again from this state, a large current flows at first, as shown in FIG. 8, and the movable iron piece is attracted to the solenoid. When the movable piece of iron is attracted to the solenoid, the inductance increases and the current flowing through the solenoid gradually decreases, and when the attraction is completed, ± as shown in the figure.
Stable at II. This change in current is detected to confirm the operation of the solenoid valve.

In such a device, there is a problem that operation cannot be detected unless the current is turned on again after being turned off (on only a failure can be detected), and it takes time for detection.

(Problems to be Solved by the Invention) As mentioned above, the conventional 'J z switch and the one equipped with an acoustic sensor have problems of installation difficulty and reliability, while other types do not operate instantly. The drawback was that detection could not be performed.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an operation detection device for a 111 solenoid valve that can instantly and reliably confirm the operation of a solenoid valve even during plant operation.

[Structure of the invention]

(Means for Solving the Problems) In the solenoid valve operation detection device of the present invention, a conversion means is provided to convert the on/off of the power supply for opening/closing the solenoid valve to the on/off of the zero potential cross point, and the solenoid valve is A resonant circuit is formed by connecting a capacitor to the coil in parallel, and from the time the power is turned off, the voltage or current that resonates in the resonant circuit is converted to nπν (n is 1) from the time the conversion means is turned off at the zero potential cross point.゜2.3..., L is the inductance of the solenoid coil, C is the capacitance of the capacitor) By measuring the time, it is compared with the reference time during normal operation of the solenoid valve to determine whether *M1yP is normal or abnormal. It is composed of

(Function) In a device configured in this way, when the power is turned off, the frequency 2πA of the voltage or current that resonates in the resonant circuit changes depending on the positional relationship between the solenoid coil of the solenoid valve and the movable iron piece (the solenoid coil's frequency 2πA changes). Inductance L
change). Therefore, by measuring nπ, & (arbitrary time) and comparing it with the reference time during normal operation of the solenoid valve, it is possible to instantly determine whether the operation of the solenoid valve is normal or abnormal after turning off the power.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Here, we will discuss the nuclear reactor emergency shutdown system (scram) using the operation detection of a solenoid valve in a nuclear power plant as an example.

Figure 4 is a schematic diagram of the reactor emergency shutdown system. When the solenoids 3 and 4 are de-energized by signals from the logic units 1 and 2 which make judgments and issue commands as a result, the solenoid valve 5 ，
6 is operated, and the compressed air 23 is exhausted through the air pipe 7 in the illustrated air exhaust direction 24. Piping 8 at the same time
The air inside is also exhausted in the exhaust direction 24, and as a result of the loss of compressed air in the pipe 8, the valves 9, 10 are opened. Valve 9, 10
is opened, compressed water 21 passes through valve 9 to piston II.
At the same time, the water in the upper part of the piston 11 is drained in the discharge direction 22 via the valve 1o. As a result, the piston 11 is rapidly pushed up by water pressure, and a control rod (not shown) is inserted into the reactor core. Even if one of the solenoid valves 5 or 6 is de-energized, the air in the pipe 8 is not lost from the flow direction of the compressed air, and the control rod is not inserted. For this purpose, each channel of logic section 1 or 2 is usually tested, and the soundness of the operation of logic section 1.degree. 2 can be confirmed.

FIG. 5 is a diagram conceptually showing the relationship between the solenoids of the electromagnetic valves 5 and 6 of FIG. 4 and the movable iron piece.

FIG. 5(b) shows an excited state, and FIG. 2(a) shows a non-excited state. When a current is applied to the solenoid 3, the movable iron piece 31 is attracted by magnetic force, and the movable iron piece 31 is attracted into the solenoid 3 as shown in FIG. 3(b). When the current flowing through the solenoid is cut off, the movable iron piece 31 is released as shown in FIG. The main body of the valve that is interlocked with the movable iron piece 31 operates in accordance with the above.

Next, FIG. 1 is a schematic block diagram showing an embodiment of the electromagnetic valve operation detection device of the present invention.

When the trip switch 52 (controls the scram signal with an existing switch in the plant) in the current trout logic units 1 and 2 supplied from the alternating power supply 50 is turned on, the 5SR51 (solid state Φ relay) switches to the zero potential point of the power supply voltage. The capacitor 53 becomes conductive (ON state) (see C and D in FIG. 2), and current is supplied to the capacitor 53 and the solenoid valve 54, respectively.

Therefore, the electromagnetic valve 54 becomes energized (FIG. 5(b)).

When the trip switch 52 is turned off, the capacitor 53 and the solenoids 3 and 4 of the solenoid valves 5 and 6 connected in parallel to the capacitor 53 are turned off.
Due to the resonant circuit (tank circuit) formed by the above, the voltage is damped at a period of t = 2π~/'LK (4 is the inductance of the solenoid 3, and C is the capacitance of the capacitor 53) (see Fig. 2B). ).

Depending on the stop position of the movable iron piece inside the solenoid valves 5 and 6, L
(inductance) changes. In other words, if the movable iron piece 31 completely comes out of the solenoid 3 when the trip switch 52 is turned off (normal condition), the inductance will be small, but if the movable iron piece 31 remains inside the solenoid 3 for some reason ( (abnormal state), the inductance becomes large.

Therefore, in advance, the vibration frequency in the normal state is 2π4
or nπl which is n times the imaging frequency (n=1.2
．． The operation of the tHi valves 5 and 6 can be confirmed by measuring the frequencies (3...) and comparing them with the frequencies actually measured by turning off the trip switch 52.

In order to realize this, t=nπ41 seconds (n is 1, 2.3, etc.) after the time when the trip switch 52 is turned off (actually, the time of zero potential converted by the zero potential cross comparator 52). The time required for the voltage value to reach the zero loss point is calculated using the circuit described below.

The detection circuit 55 converts the voltage waveforms across the capacitor 53 and the solenoids 3 of the electromagnetic valves 5 and 6 to a level suitable for the zero potential cross comparator 57 and outputs the converted voltage waveforms. A zero potential cross comparator 57 shapes the voltage waveform (spider wave) into a rectangular wave and sends it to an AND circuit 59.

On the other hand, the monostable multivibrator 56 is activated by a signal from the trip switch 52. From this monostable multivibrator 56, any desired time t=nπJ
generates a single pulse of slightly longer duration than (Fig. 2E)
) is sent to the AND circuit 59. Further, a time reference signal is sent from a reference time signal generator 58 for measuring time to an AND circuit 59 (shown in FIG. 2).
AND circuit 5 of these three signals input to circuit 59
The output from 9 is a signal corresponding to the time t=nπV40,000 to be measured. By passing this signal through the digital comparator 60, it is determined that the solenoid valve is in a normal state as determined in advance.
Compare this time with the time it took to operate. The OR and discrimination display circuit 61 can also send alarm (failure) signals from the respective digital comparators 6° all at once to a control room, etc.

FIG. 2 shows voltage waveforms of the main parts of the block diagram shown in FIG. Note that the symbols A to H in FIG. 2 correspond to the symbols A to H shown in FIG. 1, and indicate the positions of observed waveforms in the respective block diagrams.

FIG. 2A shows the on-off waveform of the trip switch 52. B shows a damped vibration waveform of a resonant circuit consisting of a capacitor 53° and a solenoid 3°4.

2. The solid line indicates normal conditions, and the broken line indicates abnormal conditions.

When an abnormality occurs, the movable iron piece remains in the solenoid even though the power is turned off and the solenoid is de-energized, and the inductance is large compared to the normal state when the movable iron piece is completely released, causing damping. It is also large at the perturbation frequency of 2πA. C9D is a rectangular wave passed through the zero-potential cross comparator 57 during abnormal and normal conditions, E is the output waveform of the monostable multivibrator 56, and F and G are AN, respectively.
Output signal waveforms during abnormal and normal times through D circuit 59.
H is the time reference No. 46 waveform.

FIG. 3 shows another embodiment of the present invention, in which a c'r (current transformer) 62 is used to detect the current value from a resonant circuit consisting of a capacitor 53 and solenoids 3 and 4.
It is a crest. In FIG. 3, parts equivalent to those in FIG. 1 are given the same reference numerals and explanations are omitted, but the operation and effect of detecting an OFF fault are the same. In other words, from the time when the trip switch 528 is turned off (actually, the time of zero potential converted by the zero potential cross comparator 57), t
The time to the zero cross point of the current value (the current value is detected by the CT621C) after = nπ−χ seconds (n is 1, 2, 3−) is detected in the same manner as described above. Then, the digital comparator 60 compares the time with the predetermined time when the solenoid valve operates normally to determine whether it is normal or abnormal.

In addition, the current of the main part of the block diagram shown in FIG.

The voltage waveform matches that shown in FIG. 2. Also, the means for detecting the current value is not limited to a CT (current transformer).

FIG. 6 and FIG. 7 show a modification of the present invention, in which 5S
One R151 is common to all circuits, and is connected to the tank circuit via a resistor 71.

Further, in the above embodiment, the time measured using the digital comparator 60 and the normal time are compared, but the frequency of the time reference signal from the reference time signal generator 58 is increased (beyond the threshold) using a counter or the like. As a result, the resolution is increased and the intermediate stop position of the movable iron piece 31 can be displayed very well.Therefore, it is also possible to confirm a failure in the case where the operation of the solenoid valve stops halfway.

The above explanation has been given using the solenoid valve used in the reactor emergency shutdown system as an example, but it is not limited to this and can be applied to any device that requires the determination of the operation of the solenoid valve. Also applicable to safety valves, direct current, and valves.

〔Effect of the invention〕

As detailed above, according to the present invention, the operation of the solenoid valve can be instantly and reliably confirmed during plant operation without modifying the existing solenoid valve.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the electromagnetic valve operation detection device of the present invention, and FIG. 2 is a waveform diagram showing voltage waveforms at various parts of the block diagrams of FIGS. 1 and 3. Fig. 3 is a block diagram showing another embodiment of the present invention, Fig. 4 is a system diagram of a nuclear reactor emergency shutdown system of an electronic power plant, and Fig. WJ5 is a conceptual diagram showing the correlation between the solenoid and the movable iron piece. 6 and 7 are block diagrams showing modified examples of the present invention, and FIG. 8 is a conceptual diagram showing the relationship between movement and current of a solenoid valve showing a conventional example. 3.4...Solenoid coil, 5,6...Solenoid valve,
31... Movable iron piece, 50... Power supply, 51... SS
R, 53... Capacitor, 55... Detection circuit, 5
6... Monostable multivibrator, 57... Zero potential cross comparator (conversion means), 58... Reference signal generator, 59... AND circuit (measuring means), 60...
・Digital comparator (comparison/discrimination means), 61...
0-liter discrimination display circuit (display means), 62...CTo

Claims (2)

[Claims] (1) A movable iron piece that is movably installed in the main body of the solenoid valve and opens and closes the solenoid valve, a solenoid coil that is installed near the movable iron piece, and a power source that supplies exciting current to the solenoid coil; a conversion means for converting the on-off of the power supply into on-off at the zero potential cross point; a resonant circuit formed by connecting a capacitor in parallel with the solenoid coil; A measuring means for measuring the time from the time of turning off to an arbitrary zero potential cross point of the voltage value or current value resonated by the resonant circuit, and the time measured by the measuring means;
An operation detection device for an electromagnetic valve, characterized in that it comprises a comparison/determination means for comparing a reference time during normal operation of the electromagnetic valve to determine whether the electromagnetic valve is normal or abnormal. (2) The electromagnetic valve operation detection device according to claim 1, further comprising display means for displaying the normal or abnormal signal detected by the comparison and discrimination means.