JPS592564Y2 - Abnormality detection device for dual input signal source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting an abnormality in an input signal source.

In order to improve the reliability of boiler automatic control devices and the like, important input signal sources such as a main steam flow rate transmitter and a main steam pressure transmitter are duplicated.

If the active side of the duplicated input signal source fails, it must be switched to the standby side, but it must be ensured that the standby side is normal before switching.

One of the conventional abnormality detection devices is one that monitors the input signal on the active side and switches to the standby side if an abnormality is detected. This is inconvenient because you won't know until you try it.

Another type of conventional abnormality detection device is one that detects an abnormality in an input signal source based on a mismatch between the signals of two input signal sources. The cause of the failure must be determined separately.

An object of the present invention is to provide a simple abnormality detection device that can determine the faulty side of a duplex signal source.

The device of the present invention is based on the result of monitoring the coincidence of the signals of the duplex signal source and the result of monitoring the rate of change of the signal of the working signal source.
This is designed to determine failures.

The present invention will be explained below with reference to the drawings.

The figure is a conceptual configuration diagram of an embodiment of the present invention.

In the figure, T1 is the input signal source on the active side, T2 is the input signal source on the standby side, MS19MS2 is the deviation monitor, LMT is the speed limiter, AND is the AND circuit, Ll, L2 are the indicator lights, and CNT is the manual control mode. It is a controller with

The signal from the input signal source T□ on the active side is input to the controller CNT, which normally operates in automatic mode and provides an output signal corresponding to the input signal to the operating target.

Deviation monitor MS1 receives input signal source T1. The difference in the T2 signals is monitored and an on output signal is generated if it exceeds a predetermined limit.

The output signal of the deviation monitor MS is given to an AND circuit AND and an indicator light L1.

The rate of change limiter LMT receives the signal from the input signal source T1, and if the rate of change exceeds a predetermined limit, the rate of change is limited to be equal to the limit and output.

The limit setting value of the rate of change is set to be slightly larger than the maximum value of the rate of change of the input signal source T1 during normal operation.

When the rate of change of the human input signal is below the limit, the rate of change limiter LMT outputs the input signal as it is.

Deviation monitor MS2 monitors the difference between the input and output of rate of change limiter LMT and produces an ON output signal if this difference exceeds a predetermined limit.

The output signal of the deviation monitor MS2 is given to an AND circuit AND and an indicator light L2.

The AND circuit AND converts the logical product of the ON output signals to the controller CN.
This signal is given to T as a manual mode designation signal.

Indicator light L1. L2 is turned on by the ON output signal.

The operation of the device configured in this way is as follows.

Input signal source T1. As long as both T2 are normal, the signals from both signal sources match, so no difference is observed by the deviation monitor MS1.

Its output signal is therefore off.

Also, since the rate of change of the signal from the input signal source T1 is below the limit, the rate of change limiter LMT outputs the input signal as it is, and therefore no difference is observed by the deviation monitor MS2, and its output signal is also turned off. be.

As a result, the output signal of the AND circuit AND is turned off, the controller CNT operates in automatic mode, and the indicator light L1. L
2 are both off, indicating that there is no abnormality.

If the input signal source T2 on the standby side fails, its signal suddenly changes to 0 or 100%.

Deviation monitor MS1 therefore senses the difference between both signals and produces an on output signal.

This lights up the indicator light L1. On the other hand, input signal source T
1 is normal, so the output signal of the deviation monitor MS2 is off.

Therefore, the indicator light L2 is off and the AND circuit A
The output of ND is also off.

Therefore, at this time, the indicator light L2 is off, indicating that the input signal source on the standby side has failed.

If the active input signal source T1 fails, its signal changes suddenly so that the rate of change of the signal exceeds the limit of the rate of change limiter.

Therefore, the rate of change limiter LMT limits the rate of change of the input signal to a value equal to the limit setting value and outputs it.

Then, the difference between the input and output is sensed by the deviation monitor MS2, and an on-output is generated.

Further, since the signal of the input signal source T1 is different from the signal of the normal human input signal source T2, the output signal of the deviation monitor MS is also turned on.

Therefore, the indicator light L1. Both L2 lights up, indicating that the input signal source T on the active side has failed.

Since both the output signals of the deviation monitors MS15MS2 are turned on, the output signal of the AND circuit AND is turned on, and thereby the controller CNT is switched to manual mode, and the influence of the failure of the input signal source T1 is transferred to the control output. spread is prevented.

Even when neither the active side nor the standby side is faulty, in some cases the input signal may change rapidly beyond the limits of the rate of change limiter.

In such a case, deviation monitor MS2 will produce an ON output signal, but deviation monitor MS1 will generate an on-output signal, but deviation monitor MS1 will not be able to handle both human power signal sources T1. T2
Since the signals change in the same way, they do not produce an on output.

For this reason, only the indicator lamp L2 is lit, and the indicator lamp Ll is not lit, so that the case can be determined.

Further, at this time, the output signal of the AND circuit AND is off, and the controller CNT is not switched to manual mode.

In this way, the controller CNT is switched to manual mode only if the active input signal source T1 really fails.

In this way, failures on the active side and standby side are determined and displayed.

In the event of a failure on the active side, the controller is shifted to manual mode, ensuring control safety.

In this way, when a duplex input signal source fails, it is determined and displayed which one has failed, so that measures such as switching or repairing the input signal source can be quickly taken.

When switching to the standby side due to a failure on the active side, the normality of the standby side has been confirmed by the state of the indicator light L1 up to that point, so the switch can be performed with confidence.

Such functionality also includes one change rate limiter and two
two deviation monitors, output indicators of these deviation monitors,
This is realized by an extremely simple configuration consisting of one AND circuit.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a conceptual diagram of an embodiment of the present invention. T1. T2...Input signal generator, MS19MS
2...°・. Deviation monitor, LMT... Change speed limiter, AM
D...AND circuit, Ll, L2...Indicator light, CNT...Controller.

Claims (1)

[Scope of utility model registration request] For signals on the active side of the duplex input signal source, if the rate of change is below a predetermined limit, the signal is output as is; if the rate of change exceeds a predetermined limit, the rate of change is limited to that limit and output. a first deviation monitor that detects a difference in the signals of the duplicated input signal source; a second deviation monitor that detects a difference between the input and output of the change speed limiter; an AND circuit that puts the controller operating based on the signal of the input signal source on the active side into manual mode by the AND of the output signals of the first and second deviation monitors, and the output signals of the first and second deviation monitors. An abnormality detection apparatus for a dual input signal source, comprising first and second indicators respectively displaying.