JPH0412229A - Abnormality detecting device - Google Patents

Abstract

PURPOSE:To directly cut off the load by a contact being important for safety by driving the load by electric power from an AC power source, when the contact is closed, and also, cutting off the load, when the contact is opened, and operating an input control circuit. CONSTITUTION:At the normal time, each contact 1 (1a, 1b...1n) is all closed, when an AC power source 3 is turned on, only one half-wave of an AC signal is supplied to a diode 14a, a relay 14b a diode 14c, and the contact 1, the relay 14b is excited, a switching contact 14e is switched from a full line state, and a load 2 operates. In this case, since the contact 1 is closed, no voltage is applied to an input control circuit 10. Subsequently, for instance, when the contact 1b is opened, no current flows to the load 2 and the load 2 is not operated, the contact 14e returns to its original state, a circuit of the contact 1a, a rectifying diode 12, a smoothing circuit 13, an isolator 11b, the contacts 1c - 1n, and the contact 14e is formed, and voltage is applied to only the isolator 11b. Accordingly, an output of the isolator 11b is supplied to a microprocessor 6, and a fault part can be detected.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to an abnormality detection device that detects the pressure and temperature of a boiler, furnace, etc., and operates or deactivates a load each time a contact is opened or closed. It is.

[Conventional technology]

Figure 3 is a circuit diagram showing a conventional abnormality detection device. In the figure, la, lb... are contacts such as interlock contacts and limit contacts that detect pressure and temperature in boilers, furnaces, etc., and 2 is a circuit diagram showing a conventional abnormality detection device. A load connected in series to these contacts 1,
3 is an AC power supply.

Next, the operation will be explained.

Since the load 2 is connected in series to the contacts 1a, lb..., when any of the contacts 1a, lb... opens, the load 2 is cut off. Although the abnormality detection device shown in FIG. 3 has excellent safety features, it
There was a problem in that it was difficult to detect the location of the failure because it could not be determined whether or not b.

Therefore, as shown in FIG. 4, a relay 4a is installed at the contacts 1a, lb, . . . so that the failure location can be detected.

4b... are connected in series, and these contacts 1a, lb...
And the series circuit of relays 4a, 4b... is connected to the AC power supply 3.
The relay 4a is connected in parallel to the relay 4a.

Contact 5a that operates by energizing and de-energizing 4b...
, 5b, . . . are connected in series to the load 2, and contacts 6a, 6b, . There is.

Although the abnormality detection device having the configuration shown in Fig. 4 can detect the failure location and solves the problem shown in Fig. 3,
When the number of contacts 1a1b... for detecting a failure increases, the number of relays 4a4b... and contacts 5a, 5 increases accordingly.
b..., 6a, 6b... increases, and new problems arise in that the configuration becomes complicated and costs and space increase.

Therefore, as shown in FIG. 5, an abnormality detection device has been devised that can easily detect which part has failed and has a simple configuration. That is, the abnormality detection device shown in FIG. 5 connects contacts 1a, Ib, etc. such as interlock contacts and limit contacts that detect pressure, temperature, etc. to the microprocessor 6 via the input circuit 8, and The configuration is such that a relay 7 is connected to the output of the microprocessor 6, and a contact 9 that operates depending on whether the relay 7 is energized or de-energized is connected in series to the load 2.

When the contacts 1a, Ib, .
will be blocked.

(Problems to be Solved by the Invention) Since the conventional abnormality detection device is configured as described above, the contact points 1a, lb... which are important for the safety of boilers, furnaces, etc.
If the input circuit 8 fails or the microprocessor 6 goes out of control or malfunctions when the load 2 must be shut off, there is a risk that the load 2 cannot be shut off.

This invention was made in order to solve the above-mentioned problems, and provides an abnormality detection device that can directly cut off a load at a contact point important for safety and that can easily input data to a central processing circuit. The purpose is to

[Means to solve the problem]

The abnormality detection device according to the present invention includes at least two contacts such as interlock contacts and limit contacts connected in series, and is cut off when the contact is open and driven by an AC power source when the contact is closed. and a load connected in parallel to this load, which operates the load when the contacts close and turns on the AC power supply, and disables the load when any one of the contacts opens. a circuit, an input control circuit connected in parallel to the contacts and activated when the load is cut off, and a central processing circuit that reads input data from the input control circuit and determines which of the contacts is open. It is equipped with the following.

[For production]

The abnormality detection device in this invention drives a load with the power supplied from the AC power supply when the contact is closed, and cuts off the load and operates the input control circuit when the contact opens, and operates the central processing circuit. It is designed to notify which contact is open by supplying an output to the terminal.

[Example〕 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit configuration diagram showing one embodiment of the present invention.
In the figures, the same or equivalent components as in FIGS. 3 to 5 are denoted by the same reference numerals, and redundant explanation will be omitted. In FIG. 1, 10 is an input control circuit, and lla, llb... are rectifier diodes 1 between both ends of each contact 1a, lb...
2 and the isolators connected through the smoothing circuit 13, the isolators lla, Ilb, . . . are composed of a light emitting element and a light receiving element. Further, the smoothing circuit 13 includes a resistor 13a and a capacitor 13b. 14 is load 2
This self-holding circuit 14 includes a diode 14a, a relay 14b, and a diode 1.
4c connected in series, and a switching contact 14e that switches the connection so that the load 2 is activated or deactivated depending on whether the diode 14d and the relay 14b are energized or de-energized.
It consists of a circuit in which these are connected in series. These two series-connected circuits and the load 2 are connected in parallel to the AC power source 3 so that only one half wave of the AC signal is supplied to the relay 14b.

Further, when the relay 14b is de-energized, the switching contact 14e is connected so that the voltage from the AC power source 3 is not applied to the load 2. The input control circuit 10 is an isolator l
1a, llb, a rectifying diode 12, a smoothing circuit 13, and a self-holding circuit 14. Note that the outputs of the isolators 11a, llb, . . . are connected to be supplied to the microprocessor 6.

Next, the operation will be explained.

Under normal conditions, the contacts 1a, lb... are all closed, so when the AC power supply 3 is turned on, the diode 14a
1 relay 14b, diode 14c and contacts 1a, l
b..., the relay 14b is excited by one half wave of the AC signal, the switching contact 14e is switched from the state shown by the solid line in the figure, and the load 2 is operated.

In this case, since the contacts 1a, Ib, . . . are closed, no voltage is applied to the input control circuit 10.

Now, when the contact 1b is opened, no current flows to the load 2, so the load 2 becomes inoperable, the relay 14b also becomes de-energized, and the switching contact 14e returns to its original state (the state indicated by the solid line in the figure). . For this reason, contact 1a, rectifier diode 12, smoothing circuit 13, isolake 11b1 contact 1c
. . . and a circuit of the switching contact 14e is formed, and voltage is applied only to the isolator Ilb. As a result, the output from the isolator llb is supplied to the microprocessor 6, and the location of the failure can be detected.

Furthermore, when contacts 1a and 1c are opened, current no longer flows to load 2, so load 2 becomes inoperable and relay 14
b is also de-energized. For this reason, the rectifier diode 12,
Smoothing circuit 13, isolator Ila, contact 1b, rectifier diode 12, smoothing circuit 13, isolator 11c1
A circuit of contacts 1d... and switching contact 14e is formed, and voltage is applied to isolators lla and llc.

As a result, the outputs from the isolators lla and Ilc are supplied to the microprocessor 6, allowing the location of the failure to be detected.

Figure 2 shows an application of the abnormality detection device of the present invention to combustion equipment such as a boiler, using a combustion valve as load 2.
If the combustion contact 15 is connected in series to this combustion valve,
Combustion can be safely controlled in abnormal situations such as when gas pressure rises or the temperature becomes abnormally high.

[Effects of the Invention] As described above, according to the present invention, the abnormality detection device drives the load with the power supplied from the AC power supply when the contact is closed, and cuts off the load when the contact is opened. The structure is configured so that the input control circuit is operated by the central processing circuit, and output is supplied to the central processing circuit to notify which contact is open.This allows the load to be cut off directly at the contact important for safety, and it is easy to connect the central processing circuit to the input control circuit. This has the effect of providing something into which data can be input.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an abnormality detection device according to an embodiment of the present invention, FIG. 2 is a configuration diagram showing an application example using the abnormality detection device shown in FIG. 1, and FIG. 3 is a conventional abnormality detection method. 4 is a circuit diagram showing an example of the device; FIG. 4 is a circuit diagram showing another example of the conventional abnormality detection device; FIG. 5 is a circuit diagram showing still another example of the conventional abnormality detection device. be. la, lb... Contact, 2... Load, 3... AC power supply, 6... Microprocessor, 10... Input control circuit, 14... Self-holding circuit. Patent applicant Yamatake Honeywell Co., Ltd. Agent Patent attorney 1) Hiroshi Sawa (2 others) -10=

Claims (1)

[Claims] Interlock contacts with at least two connected in series
A load that is cut off when this contact opens and is driven by the AC power supply when the contact is closed, and a load that is connected in parallel to this load and that is connected in parallel to the load and is A switching circuit that operates the load when the power is turned on and disables the load when any one of the contacts is opened, and a switching circuit that is connected in parallel to the contacts and operates when the load is cut off. An abnormality detection device comprising: an input control circuit for controlling the input control circuit; and a central processing circuit for reading input data from the input control circuit to determine which of the above-mentioned contacts is open.