US3623047A - Annunciator unit - Google Patents

Abstract

This invention relates to a fault warning annunciator having red and green lamps giving signals to indicate fault and normal conditions respectively, one or other of the lamps being energized at any time. Each lamp operates in an insistent mode until an operator acknowledges the signal by pressing a button switch whereupon the lamp operates in a less insistent acknowledged mode. The button switch is a two-position mechanical switch which changes over the modes of operation of the lamps alternately between conditions in which one lamp is in its insistent mode and the other lamp is in its acknowledged mode and vice versa, whereby when the button switch is pressed to acknowledge a signal from one lamp, the other lamp is automatically reset to operate in its insistent mode when next energized.

Description

United States Patent [72] Inventor John Stallebras 15 Adam and Eve Mews, London, W.8., England [21] Appl. No. 743,163 [22] Filed July 8, 1968 [45] Patented Nov. 23, 1971 [32] Priority July 18, 1967 [3 3] Great Britain 1 32,912/67 [54] ANNUNCIATOR UNIT 4 Claims, 4 Drawing Figs.

[52] 11.8. C1 340/213.1, 340/332, 340/378 [5 1] int. Cl ..G08h 29/00, 00% 21/00 [50] Field olSeareh 340/332, 213.1

[56] References Cited UNlTED STATES PATENTS 568,374 9/1896 Sellner 340/332 Primary Examiner-Thomas B. Habecker Attorney-Holcombe, Wetherill & Brisebois ABSTRACT: This invention relates to a fault warning annunciator having red and green lamps giving signals to indicate fault and normal conditions respectively, one or other of the lamps being energized at any time. Each'lamp operates in an insistent mode until an operator acknowledges the signal by pressing a button switch whereupon the lamp operates in a less insistent acknowledged mode. The button switch is a two-position mechanical switch which changes over the modes of operation of the lamps alternately between conditions in which one lamp is in its insistent mode and the other lamp is in its acknowledged mode and vice versa, whereby when the button switch is pressed to acknowledge a signal from one lamp, the other lamp is automatically reset to operate in its insistent rn ode when next energized.

PATENTEDunv 23 I9?! 3, 623 O47 SHEET 1 OF 2 8a MAM 1e Inventor J'euu S'rmwszass wil wwu mu t orneys ANNUNCIATOR UNIT This invention relates to annunciators of the kind which, by two distinct visual signals, with which audible signals may be associated, can indicate whether a parameter of any piece of equipment lies within acceptable operating limits or not, each signal being given first in an insistent mode and, when acknowledged by an operator, reverting to a less insistent mode. A typical sequence of signals is a flashing red light and a hooter indicating a fault condition changing to a steady red light when the operator pushes a button switch to acknowledge that he has noted the fault, and a flashing white light indicating that the condition is back to normal changing to a steady white light when the operator again pushes the button switch to acknowledge that he has noted the return to normal.

Annunciators of this kind can, of course, be used to indicate which of two alternative normal conditions obtains in relation to a piece of equipment but their simplest application is in fault warning systems and therefore fault and nonnal conditions will be referred to herein except where specifically inappropriate.

Frequently, where large numbers of annunciators are used, the pushbutton switch by which the operator acknowledges a fault or a return to normal is common to several or all the annunciators. It has been found however that this is unsatisfactory in that the operator can acknowledge a fault by pressing the button without really appreciating what the fault is, particularly when two or more annunciators signal an abnonnal condition at the same time. For this reason, it is preferred to have a separate acknowledging switch for each annunciator, so that the operator must find out which of the annunciators is or are signalling a fault.

An annunciator must be actuated by a fault-sensing element in which a pair of electrical contacts close, or preferably open when the parameter passes outside its acceptable limits. it is not usually practicable or, in the interests or reliability, desirable for the contacts in the sensing device to handle the power required to operate the warning lights and hooters of the annunciator which must therefore include electrically operated switches. Ordinary electromechanical relays are potentially unreliable, and so more sophisticated arrangements such as reed relays or transistor switches are preferably used.

Although the circuitry which determines whether a fault or a normal condition is signalled must clearly be of the highest possible reliability, the switching which changes the fault or return to normal signal to the acknowledged mode, need not be so reliable and it is usual for the pushbutton switch, used by the operator to acknowledge a fault or return to nonnal signal, to be of simple mechanical design merely to send a pulse to the high-reliability circuitry to change the signal to the acknowledged mode. This has two disadvantages, first that the high-reliability circuitry must be able to respond to the acknowledging pulse as well as to the fault-sensing element and must therefore be correspondingly more complex which means in practice more expensive and at least potentially less reliable and second, that the acknowledging switch sends the same pulse signal whether a fault or a return to normal is being acknowledged and therefore cannot conveniently be used for any other purpose, to actuate a device which will restore the fault condition to normal for example.

in accordance with the present invention, these disadvantages are overcome in an annunciator of the kind described in which there are two visual signalling devices both arranged to be energized by operation of a sensing element through electrically operated switching, one during fault conditions in a first mode corresponding to a fault occurring and in a second mode corresponding to acknowledgement of the fault, the other during normal conditions in a first mode corresponding to the normal condition being restored and in a second mode corresponding to acknowledgement of the return to the nonnal condition, and a manually operated switch which changes over the modes of operation of the two devices alternately between conditions in which one device is in its first mode and the other device is in its second mode and vice versa. With this arrangement, when the manual switch is operated to acknowledge a signal from one of the devices, the other device is automatically reset to operate in its first mode when next energized.

The electrically operated switching, which only causes the alternate energization of the two signalling devices without any discrimination as to their mode of operation, must be highly reliable since it determines whether a fault or a normal condition is signalled and may suitably be a reed relay or a transistor switch.

The signals may take the form of red and white lamps to indicate fault or normal conditions respectively the lamps having a flashing first mode changing to a steady second mode after acknowledgement. The manually operated switch may then be a mechanical two-position switch applying a continuous voltage to the white and an intermittent voltage to the red lamp in one position and intermittent voltage to the white and a continuous voltage to the red in the other position, a circuit including either the red or the white lamp being completed by the electrically operated switching.

The two-position acknowledging switch has the advantage that it can also be used to operate a device which will restore the fault condition to normal. For example, if the fault is the overheating of a component, the switch acknowledging the fault can be ganged to a simple on/off switch operating a fan to cool the component. When the components temperature is back to normal, acknowledging the return to normal signal will switch off the fan. Where the acknowledging switch is a pushbutton sending a pulse to the electrically operated switch this is impracticable since even if the fan is arranged to be switched on and off by alternate pulses, if a fault corrects itself without having been acknowledged, acknowledgement of the return to normal will switch the fan on, which is the opposite of what is wanted. The only way to ensure that the fan operates in step with the annunciator signals involves complicating the electrically operated switching still further.

When the annunciator is used to indicate which of two alternative, norrnal conditions applies in relation to any piece of equipment, the two-position acknowledging switch can be used to operate a device which changes the equipment from one condition to the other. The annunciator then indicates which of the two conditions applies, according to which signalling device is energized, and whether this is in agreement with the operation of the device which changes the condition, according to the mode in which the signalling device is energized. Arrangements of this kind, which give a warning when there is a discrepancy between the actual condition of a piece of equipment and the condition expected by virtue of the operation of a device which affects the condition, are known as discrepancy warning systems and it is an advantage of the present annunciator that it is suitable for such systems.

One example of an annunciator constructed in accordance with the invention, and three examples of its use, are illustrated in the accompanying drawings, in which:

FIG. 1 is a sectional plan of the annunciator;

FIG. 2 is a diagram of a fault warning circuit incorporating the annunciator;

FIG. 3 is a circuit diagram of a discrepancy warning circuit incorporating the annunciator; and,

FIG. 4 is a second discrepancy warning circuit incorporating the annunciator.

As shown in FIG. 1, the annunciator has a case 5 at one end of which two lamps 6a and 6b are mounted. A cover 7, made from transparent material, closes the end of the case adjacent to the lamps and is movable relatively to the case 5 in a direction towards the lamps from the position shown against a resilient bias. A red filter 8 is mechanically biased to surround the lamp 6a and is movable so that the lamp can be replaced if necessary.

A pawl 9 extends from the cover 7 between the two lamps towards a ratchet 10 which has eight teeth and is rotatably mounted together with a square cam 11. Movement of the cover 7 towards the lamp causes the pawl 9 to engage the ratchet l and rotate both the ratchet and the cam through oneeighth of a turn, thus either depressing or releasing a spring arm 12 and operating a spring-loaded switch unit l3 which is in contact with the arm l2.

The casing 5 also houses a pair of reed switches Ma and 14b and has projecting from the end opposite to the cover 7 a number of contact pins 15.

As shown diagrammatically in FIG. 2, the reed switch 14a has two contacts 17 and 18 and these are arranged to be open when a fault-sensing element signals a normal condition and vice versa. The switch 14b also has two contacts, 19 and 20 but these are arranged to be closed during normal conditions and vice versa. Thus one or other of the two pairs of contacts 17 and I8, and 19 and 20, are always closed, but never both at once. The contact 17 is connected to one of two terminals of the lamp 6a and the contact 19 is connected to one of two terminals of the lamp 6b. The other terminal of the lamp 6a is connected to that of the lamp 6b and a continuous positive voltage is applied to both.

The switch unit 13 comprises two switches 13a and 1317 which are arranged to move together between two positions in one which the contact 18 is connected, by one of the pins 15, to an intennittent source a and the contact is connected to a continuous negative source 15b and in the other of which the contact 18 is connected to the steady negative source 1517 and the contact 20 is connected to the intermittent source 150.

In the position shown of the switches 13a and 13b, the lamp 6b is connected between the steady positive source and the steady negative source and is therefore energized continuously, whereas the circuit including the lamp 6a is open at the contact 17 and the lamp 6a is therefore not energized. This configuration corresponds to normal operation of the associated equipment. Should an abnormal condition develop, the fault-sensing element causes the contacts 19 and 20 to open and the contacts 17 and 18 to close. The lamp 6b is therefore open circuit and the lamp 6a is connected between the positive source and the intermittent source and flashes to indicate a fault.

To acknowledge the fault, the operator presses the cover 7 and reverses the position of the switches 13a and 13b. The contact I8 is then connected to the steady negative source 15b with the result that the lamp 6a is lit continuously. When the fault clears, the fault-sensing element causes the reed switches 14a and 14b to return to the positions shown in FIG. 2, opening the contacts 17 and 18 and closing the contacts 19 and 20. The lamp 6b is then connected to the intermittent source 150 and flashes indicating the return to normal. Finally the operator returns the switches 13a and 13b to the positions shown in FIG. 2 acknowledging the return to normal and connecting the lamp 6b to the steady negative source.

The intermittent source supplies pulses which are alternately positive and negative with respect to the continuous positive source. If desired, a klaxon or other audible warning device can be associated with the lamp 6a and be arranged to be energized only when the contact 17 is positive with respect to the positive voltage source. An audible warning is then given only when the lamp 6a is in its flashing mode indicating the presence of an unacknowledged fault.

The reed switches determine whether a fault or normal condition is indicated and are of the highest possible reliability. They are therefore inevitably expensive. The switches 13a and 13b on the other hand merely determine in which mode the lamp (in or 6b selected by the reed relays, is energized. Failure of the switches 13a and 13b is much less serious and is in any case immediately apparent to an operator since operation of the switches 13a and 13b, by depressing the cover 7, should always change the mode of operation of whichever lamp is energized. The switch unit 13 is therefore of simple, mechanical design.

If further switches are included in the unit 13, they can control equipment which affects the fault condition. For example, where the fault is the overheating of a component, the switch unit 13 can include contacts which are open when the switches 13a and 1315 are in the position shown in FIG. 1 and are closed in the other position, to switch on a cooling fan. The fan would then be switched on when overheating of the component was both indicated and acknowledged and would be switched off again upon acknowledgement of the return to normal of the temperature. An arrangement of this kind is suitable in any circumstances where a relatively simple switching step is to be taken when a fault is indicated.

The inclusion of a further switch in the switch unit 13 also enables the annunciator to be used for discrepancy warning. In the example shown in FIG. 3, the circuit is identical to that in FIG. 2, with the addition of a pump 2], a sensing element 22. a detector 23 and an on/otf switch 13c which forms part of the switch unit 13 and is ganged to the switches 13a and 13b.

The sensing element contains a pair of contacts, which are closed when low pressure in a delivery line 24 from the pump 21 is sensed by the element 22 and open when the pressure is high. The detector governs the reed switches Ma and 14b in response to the open or closed conditions of the contacts in the sensing element.

in the position shown, the pump is off, the pressure in the line 24 is correspondingly low and the sensing contacts are closed with the result that the detector has closed the contacts 19 and 20 and opened the contacts 17 and 18. The switch 13b connects the contact 20 to the steady negative voltage 15b and therefore the lamp 6b is lit continuously. When the switch BC is operated to energize the pump 21, the switches 13a and l3bb are simultaneously operated so that the contact 20 is connected to the intermittent source 15a causing the lamp 6b to operate in a flashing mode. When the pressure in the line 24 builds up to an acceptable value, the contacts in the sensing element 22 open, whereupon the detector 23 causes the reed switches 14a and 14b to change over, the contacts 17 and 18 closing and the contacts 19 and 20 opening. This extinguishes the lamp 6b and connects the lamp 6a to the steady source 15b.

When the pump is turned off, by operation of the switch 130, the switches 13a and [3b are also changed over, so that the lamp 6a is energized by the intermittent source 15a and the contact 20 is connected to the steady source 15b. Finally when the pressure drops, the contacts in the sensing element close and the detector causes the switches 14a and 14b to revert to the positions illustrated so that the lamp 611 is lit continuously. Low pressure is therefore indicated by the lamp 6b, as a normal condition with the pump off by a steady signal, and as an abnormal condition with the pump on by an intermittent signal, and similarly with high pressure.

The circuit shown in FIG. 4 is a valve control arrangement with discrepancy warning. The switch is a two-position switch which energizes a servomechanism 25 one way to open the valve and another way to close the valve, according to the position of the switch which is illustrated in the position operating the mechanism 25 to close the valve. A contact 26 moves with the valve from a position as shown when the valve is closed in which it is connected to a first contact 27 in a detector 28 to a position in which the valve is open and the contact 26 is connected to a second contact 29 of the detector 28. A line 30 is arranged to short circuit the contacts 26 and 27 when the switch 13c is changed from the position shown in order to open the valve. The detector 28 governs the reed switches 14a and 14b in such a way that they will adopt the position shown only when the contacts 26 and 27 are connected, either directly or through the line 30 and the switch 13c, and the contacts 26 and 29 are open circuit. If either the contacts 26 and 27 are disconnected or the contacts 26 and 29 are connected, the switches 14a and 14b will both be changed over.

With the circuit as shown, the switch BC is set to cause the servomechanism 25 to close the valve and the valve is closed. The contacts 26 and 27 are closed and the contacts 26 and 29 are open with the result that the reed switches 14a and 141; are as shown with the contacts 17 and 18 open and the contacts l9 and 20 closed. The lamp 6b is connected to a continuous source b through the switch 13b and is therefore lit continuously.

To open the valve the position of the switch 13c is changed, operating the servomechanism and connecting the contacts 27 and 26 through the line 30. The ganged switches 13a and 13b are also changed connecting the lamp 6b to the intermittent source 150 and the contact 18 to the steady source 15b. As the valve moves from the closed position the contact 26 moves away from the contact 27 but this has no effect on the reed switches 14a and 141) because the contacts 26 and 27 are still connected through the line 30. The lamp 6b therefore operates in its flashing mode.

When the valve reaches its fully open position, the contact 26 touches the contact 29 and causes the switches 14a and 14b to change over. The lamp 6b is then open circuit and the lamp 6a is connected to the steady source 15b.

To close the valve, the switches 13a, 13b and 13c are returned to the position illustrated connecting the lamp 6a to the intermittent source and breaking the connection between the contacts 26 and 27 at the switch 13c. As the valve closes, the contact 26 breaks with the contact 29 but, because the contacts 26 and 27 are open circuit, this has no efiect on the relays 14a and 1412. When the valve is finally closed, the contacts 26 and 27 close so that the detector causes the reed switches 14a and 14b to revert to the positions illustrated with the lamp 6b lit steadily.

I claim:

1. An annunciator comprising first and second signalling devices, first and second circuits including said first and second signalling devices respectively, steady and discontinuous electrical current sources adapted to energize said signalling devices in steady and pulsating modes respectively, a relay including two switching means, one controlling each circuit, said relay having two configurations, in one of which said first circuit is closed and said second circuit is open, and in the other of which said first circuit is open and said second circuit is closed, manually operable two-position switching means which in one position connects said steady electrical current source into said first circuit and said discontinuous electrical current source into said second circuit, and which in the other of said positions connects said discontinuous source into said first circuit and said steady source into said second circuit, whereby said relay determines which of said two signalling devices is energized and said manually operable switching means detennines in which of said modes said signalling device is energized.

2. An annunciator according to claim 1, wherein said relay includes two armatures in a common magnetic field and each switching means of said relay comprises a pair of contacts adapted to be open and closed by a respective one of said armatures.

3. An annunciator according to claim 1, wherein said manually operable switching means comprises a plurality of two-position, ganged, mechanical switches.

4. A discrepancy warning system comprising a component adapted to adopt either one of two states, means for sensing the state adopted by said component, means for controlling the state of said component being operable one way to cause said component to adopt one state and operable another way to cause said component to adopt the other state, first and second signalling devices, first and second circuits including said first and second signalling devices respectively, steady and discontinuous electrical current sources adapted to energize said signalling devices in steady and pulsating modes respectively, a relay including a pair of contacts in said first circuit adapted, in response to said sensing means, to open in said one of said states of said component and to close in said other of said states, and a second pair of contacts in said second circuit adapted in response to said sensing means to close in said one of said states of said component and to open in said other of said states, manually operable two-position switching means adapted in one position to connect said steady source into said first circuit and said discontinuous source into said second circuit and to operate said controlling means one way and adapted in another position to connect said discontinuous source into said first circuit and said steady source into said second circuit and to operate said controlling means said other way,

Claims (4)

1. An annunciator comprising first and second signalling devices, first and second circuits including said first and second signalling devices respectively, steady and discontinuous electrical current sources adapted to energize said signalling devices in steady and pulsating modes respectively, a relay including two switching means, one controlling each circuit, said relay having two configurations, in one of which said first circuit is closed and said second circuit is open, and in the other of which said first circuit is open and said second circuit is closed, manually operable two-position switching means which in one position connects said steady electrical current source into said first circuit and said discontinuous electrical current source into said second circuit, and which in the other of said positions connects said discontinuous source into said first circuit and said steady source into said second circuit, whereby said relay determines which of said two signalling devices is energized and said manually operable switching means determines in which of said modes said signalling device is energized.

2. An annunciator according to claim 1, wherein said relay includes two armatures in a common magnetic field and each switching means of said relay comprises a pair of contacts adapted to be opened and closed by a respective one of said armatures.

3. An annunciator according to claim 1, wherein said manually operable switching means comprises a plurality of two-position, ganged, mechanical switches.

4. A discrepancy warning system comprising a component adapted to adopt either one of two states, means for sensing the state adopted by said component, means for controlling the state of said component being operable one way to cause said component to adopt one state and operable another way to cause said component to adopt the other state, first and second signalling devices, first and second circuits including said first and second signalling devices respectively, steady and discontinuous electrical current sources adapted to energize said signalling devices in steady and pulsating modes respectively, a relay including a pair of contacts in said first circuit adapted, in response to said sensing means, to open in said one of said states of said component and to close in said other of said states, and a second pair of contacts in said second circuit adapted in response to said sensing means to close in said one of said states of said component and to open in said other of said states, manually operable two-position switching means adapted in one position to connect said steady source into said first circuit and said discontinuous source into said second circuit and to operate said controlling means one way and adapted in another position to connect said discontinuous source into said first circuit and said steady source into said second circuit and to operate said controlling means said other way.

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