JPS59216419A - Defect detecting circuit of solenoid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a circuit for detecting a failure such as a disconnection of a solenoid or a stick of an armature.

[Background of the invention]

Generally, the excitation method for trip solenoids used for emergency shutdown of turbine generators, circuit breakers, etc. is to leave them in a de-energized state during normal times in order to ensure reliability during shutdown.
At the time of trip, it is energized only during the period when the cut-off operation is completed.
Thereafter, it is brought into a de-energized state again and the cut-off state is self-maintained by a mechanical mechanism.

The configuration diagram of a shutoff valve to which such an excitation method can be applied is shown in the first diagram.
FIG. 2 shows the excitation circuit of the solenoid. The valve body of the shutoff valve 12 is adapted to be interlocked with an armature (not shown) driven by the solenoid 10. The limit switch 1 with a normally closed contact is still attached to the shutoff valve 12.
1 is provided in association with the limit switch 1.
1 is configured to open when the solenoid 10 is energized and the valve body is displaced to a predetermined shutoff position.

The solenoid 10 is connected to the excitation power source ft via a series circuit of normally open contacts 1 to 5 connected in parallel with the limit switch 11.
Connected to M21 and M22. The normally open contacts 1 to 5 are contact signals that are closed by a trip command, and are not limited to five as shown in the figure.

The operation of the cutoff valve 12 and the excitation circuit configured in this way will be explained using FIG. 3. First, before the trip command is given, the normally open contacts 1 to 5 are open, and the limit switch 11 is closed.

When any of the normally open contacts 1 to 5 is closed at 11 and a trip command is given, excitation of the solenoid 10 is started and at the same time, the shutoff operation of the shutoff valve 12 is started. When the shutoff operation is completed at t2, the valve body of the shutoff valve 12 is restrained by a mechanical self-holding mechanism (not shown), and the limit switch 11 is opened. This causes the solenoid 10 to be de-energized.

However, if the solenoid IO is disconnected, the shutoff valve 12 will not be operated even if a trip command is given, so there is a risk that emergency shutoff will not be possible and a major accident will occur. Therefore, conventionally 1 solenoid 10
In order to detect a wire breakage and issue an alarm, a wire breakage detection circuit shown in FIG. 4 has been devised. That is, a failure detection relay 40 consisting of a normal heavy pressure relay with high internal impedance is connected in parallel to the series circuit of the normally open contacts 1 to 5 and the limit switch 11, and the normally closed contact 41 is connected to the alarm relay 5.
The normally open contact 51 of the alarm relay 50 is inserted and connected to the excitation circuit of the alarm relay 50 to output it as an alarm signal. The failure detection relay 40 operates with a minute current, and is selected so that the solenoid 10 is not operated by the excitation current. Therefore, the failure detection relay 40 becomes de-energized.
That is, by closing the normally closed contact 41, disconnection of the solenoid 10 can be detected. In addition, during the time until the normally open contacts 1 to 5 operate and the limit switch 11 is opened (T shown in FIG. 3), the failure detection relay 40
is in a de-energized state, so the normally closed contact 41 is closed, resulting in erroneous detection. In order to prevent this, the q-reporting rate 5
Normally open contacts 1 to 5 for 5 trip commands and normally closed contacts 31 to 35 for reverse mode are connected in series and inserted into the excitation circuit of 0.

However, according to the conventional example shown in FIG.
5 and the normally closed contacts 31 to 35 in the opposite mode are required, but this cannot be applied if the normally closed contacts 31 to 35 are not prepared. Another disadvantage is that the alarm circuit becomes complicated.

Therefore, a system as shown in FIG. 5 has been devised in which the above-mentioned reverse mode normally closed contacts 31 to 35 are eliminated to simplify the display circuit. That is, as shown in FIG. 5, in order to prevent false alarms while the normally open contacts 1 to 5 are in operation, a detection relay 45 is connected in parallel to the solenoid 10, and the normally closed contacts 46 of this relay are connected in parallel.
is inserted in series into the excitation circuit of the alarm relay 50, and when it is detected that the normally open contacts 1 to 5 are closed between To, the excitation circuit of the alarm relay 50 is released.

However, according to this example, when the solenoid IO is disconnected,
It is necessary to prevent the detection relay 45 from operating due to the current flowing through the series circuit of the detection relay 45 and the failure detection relay 40. Therefore, the detection relay 40 must be a special one with very high internal impedance, for example, one formed using an electronic circuit. However, such electronic circuits have low surge resistance and may be damaged or malfunction due to surges generated when the solenoid 10 operates. In addition, if a short circuit occurs due to damage, etc., the solenoid IO will not be energized even if the normally open contacts 1 to 5 are closed by a trip command, so it will not be possible to perform an emergency cutoff, resulting in a fatal problem of low reliability. There are some drawbacks.

[Object of the present invention]

An object of the present invention is to provide a solenoid failure detection circuit that has a simple configuration and high reliability.

[Summary of the invention]

In the present invention, a minute current is constantly passed through a solenoid through a failure detection relay, a timer for good news is excited through a normally closed contact of this failure detection relay, and a normally open contact of this timer is energized. The present invention is intended to have a simple configuration in which the signal is output as a failure detection signal, and to improve reliability.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on examples.

FIG. 6 shows a circuit configuration diagram of an embodiment of the present invention.

As shown in FIG. 6, the alarm circuit is formed by connecting an alarm timer 55 to the excitation power supply bus 23, 24 via the normally closed contact 41 of the failure detection relay 40, and connects the normally open contact 56 of the timer 55 to the excitation power supply bus 23,24. It is designed to be output externally as a failure detection signal. The settling time TM of the timer 55 is set to be sufficiently longer than the time l1lo.

The operation of the embodiment configured as described above will be explained with reference to the time charts shown in FIGS. 7 to 9.

FIG. 7(a) is an explanatory diagram of the operation when the solenoid 1o is normal. When any of the normally open contacts 1 to 5 is closed at time 11, the solenoid 1o is energized, the failure detection relay 40 is deenergized, and the timer 55 is energized. However, since the settling time of the timer 55 is TM as indicated by the arrow in the figure, the normally closed contact 56 remains open.

Next, when the operation of the cutoff valve 12 is completed at time 12 within the above TM time, the limit switch 11 is opened and the failure detection relay 40 is energized again.

As a result, the timer 55 is demagnetized (reset) and the state of the normally open contact 56 does not change at all, so the solenoid 10 is determined to be normal.

, FIG. 7(b) is an explanatory diagram of the operation when the solenoid 10 is disconnected. In normal times, when all of the normally open contacts 1 to 5 are open, the limit switch 11 is closed. If a disconnection failure occurs in the solenoid 10 at time 13, the failure detection relay 40 is immediately demagnetized, so the normally closed contact 41 is closed. As a result, the timer 55 is excited, and when a certain period of time TM has elapsed in this state, the normally open contact 56 is closed at time t4 and is output as a failure signal, thereby reporting the failure of the solenoid 10.

FIG. 7(C) is an explanatory diagram of the operation when the cutoff valve 12 does not operate even though the solenoid IO is normally excited. 1. If the normally open contacts 1 to 5 are closed at this point, the solenoid 10 is energized, but if the cutoff valve 12 does not operate due to a stake or the like, the limit switch 11 remains closed. Therefore, solenoid 1
Since o cannot be de-energized, failure detection relay 40i1:t
, the demagnetized state continues from the point in time. This state is timer 5
At time point 16, which is equal to or longer than the settling time TM of 5, the normally open contact 56 closes, thereby issuing a failure alarm.

〔Effect of the invention〕

As described above, according to the present invention, the configuration can be simplified, and erroneous detection can be prevented and reliability can be improved. Further, it has the effect of being able to detect not only disconnection failures in solenoids, but also stick failures in mechanical systems such as armatures and valve bodies.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an example of a shutoff valve to which the present invention can be applied;
1 is an excitation circuit diagram of the illustrated shutoff valve, FIG. 3 is an explanatory diagram of operation, FIGS. 4 and 5 are circuit configuration diagrams of a conventional example, and FIG. 6 is a circuit diagram of an embodiment of the present invention. , Figures 7(a) to (C)
FIG. 6 is an explanatory diagram of the operation of the embodiment shown in FIG. 1 to 5... Normally open contact, 10... Solenoid, 11.
...Limit switch, 12...Shutoff valve, 40...
Failure detection circuit, 41... Normally closed contact, 55... Timer, 56... Normally 4th (2) 1 2 34! ; Child 5 Figure 7 (b) (C)

Claims (1)

[Claims] 1. In a failure detection circuit for a solenoid that is connected to an excitation power source through a series circuit of a normally open contact that is closed by an operation command and a normally closed contact that is opened when the armature driven by the solenoid is displaced by a full stroke. ,
A failure detection circuit for a solenoid, characterized in that a minute current is constantly passed through the solenoid via a failure detection relay, and a failure signal is output when a normally closed contact of the failure detection relay is closed for a certain period of time.