JPS62278494A - Contact abnormality monitor device for reed switch - 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 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a contact abnormality monitoring device for a position detection switch of a nuclear reactor control rod.

[Conventional technology]

2. Description of the Related Art Conventionally, methods for monitoring the operation of various contact signals have been considered in electrical circuits that handle contact signals. In the European system, an input monitoring module is used to capture contact signals using a 4- or 5-core cable instead of the 2-core cable that would normally be used to monitor contact malfunctions, including cable breaks.

Although it is not a contact of a field switch such as a limit switch, JP-A-49-61575 discusses the operation, monitoring, and device for the output contact of a Suntalock circuit.

[Problem that the invention seeks to solve]

The conventional contact monitoring device described above requires one contact monitoring circuit for each contact, and the monitoring circuit itself is a complicated circuit, so it is economical to apply the monitoring device in consideration of the importance of contact signals. It's not a good idea.

An object of the present invention is to perform abnormality monitoring of a reed switch for indicating the position of a nuclear reactor control rod using an ifj logic circuit such as an hour wheel.

[Means for solving problems]

In FIG. 1, the position of a control rod 2 in a nuclear reactor 1 is detected by a reed switch 3, and is displayed by a lamp 7 on a central control panel 6 via an interlock relay panel 4. In the present invention, the monitoring of individual contacts of the reed switch 3, which was conventionally performed by the interlock relay board 4, is stopped, and instead, the logic circuit 5 monitors and displays abnormalities in the contacts of the reed switch 3.

[Effect]

FIG. 2 is a specific circuit diagram of the above logic circuit.

The principle of contact abnormality detection will be explained using this figure. There are 11 reed switches at 10% intervals from 0% to 100%, and they are labeled A to K. Further, the state of each part in the logic circuit 5 is represented by lowercase letters of the alphabet.

There are two types of reed switch contact abnormalities: (1) cases in which the contacts are welded, and (2) cases in which the contacts remain open and do not close. Welded contacts are detected by the welding detection circuit 8, and open contacts are detected by the open circuit. Detected by circuit 9. Both the weld detection circuit 8 and the open detection circuit 9 are 2-out-of-11 circuits that output 1 when two or more inputs become 1.

First, detection of welding of contacts will be explained. The control rod is now at the 10% position and reed switch B is closed. If you insert the control rod further from this position, the B contact will break and the C contact at the 20% position will open, but if the B contact is welded and the control rod does not break even after leaving the 10% position. Since both the B contact and the C contact are made, the welding detection circuit 8 outputs 1 and detects welding. In other words, as long as the control rod is in one position, only 1 out of 11 limit switches should be made, so we think that two or more limit switches are made at the same time because the contacts are welded.

Next, contact open detection will be explained. The control rod is now at the 10% position and the contact of reed switch B is made. The contact signal B is held by a self-holding circuit and a signal C is output. Output C cuts the self-holding circuit of A and C. When the control rod is further inserted from this position, contact C is made and outputs signal C, the self-holding circuit between contact B and the contact is cut off, and its own circuit is self-holding. In this way, when all the contacts are normal, the self-holding circuits of the front and rear contacts are always cut off, so the open detection circuit 9 will never operate, but even if the control rod position changes from 10% to 20%. Control rod position is 40 with contact C not closed and open.
%, if the contact is turned off, the signal d of the contact C circuit will not be output, and the self-holding circuit of the contact B circuit will not be disconnected, so the open detection circuit 9 will receive two signals, signal C and signal e. Two signals are input at the same time, and an open circuit can be detected.

In other words, unless the contact is made, the circuit will not cut off the self-holding circuits before and after it, so two or more signals can be input to the open detection circuit and detected. However, in order to distinguish it from the case of welding, the negative output of the output a of the welding detection circuit 8 is used as an AND circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

The position of the control rod 2 in the reactor 1 is detected by the limit switch 3, and the control rod 2 is detected through the logic circuit 5 in the interlock relay panel 4.
The position is indicated by a lamp 7 on the central control panel 6. Abnormal limit switch (welding).

Open) is judged by the logic circuit 5, and is indicated by the contact open indicator lamp 10 and the weld indicator lamp 11 on the central control panel 6.According to this embodiment, a contact abnormality monitoring device is provided for each limit switch. Limit switch abnormalities can be detected with a simple and economical circuit.

Further, a synchro transmitter 12 is installed on the control rod 2 to detect its continuous position, and the signal is converted by a signal converter 13 and displayed on an indicator 14. By comparing the indicator 14 and the indicator lamp 7, it is possible to confirm which limit switch is abnormal. For example, when contact welding occurs, two or more position indicator lamps 7 are lit at the same time as the welding indicator lamp 11 lights up, so the lamps that are lit other than the indicator lamps that match the indicator 14 are likely to be welded contacts. You can see that this is the indicator lamp for the switch that is on.

If the contact remains open, the open indicator lamp 10
The contact that lights up and the 1 position indicator lamp 7 remains open (it lights across the lamp indicated by No. 3, so you can detect which contact remains open. , it can also be detected by comparing with the indicator 14.

〔Effect of the invention〕

According to the present invention, it is possible to detect contact abnormalities (welded or open contacts) of reed switches using a relatively simple logic circuit without providing a contact abnormality monitoring device for each control rod position detection reed switch. This has the effect of greatly reducing the number of circuit components and improving reliability and economical efficiency compared to the case where individual detection devices are provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a detailed diagram of the logic circuit of FIG. 1, and FIG. 3 is a block diagram of another embodiment. 1... Nuclear reactor, 2... Control rod, 3... Reed switch, 4... Interlock relay board, 5... Logic circuit, 6... Central control board, 8... Contact Welding detection circuit, 9... Contact open detection circuit, 12... Synchro oscillator, 13... Signal converter.

Claims (1)

[Claims] 1. The reed switch that detects the position of the reactor control rod and the reed switch are incorporated into a logic circuit, and the mutual states of the reed switches are compared and determined using logical operations to monitor abnormalities in the reed switch contacts. Features: Reed switch contact abnormality monitoring device.