Alarm Sensing And Indicating Systems

Abstract

A supervised alarm circuit using low energy of one polarity for supervision. The circuit is energized at a higher level in response to sensing an alarm condition which pole changes the circuit to energized alarm devices in response to the pole changing of the circuit.

Description

This invention relates to alarm-sensing and alarm-indicating systems, and it more particularly pertains to alarm-sensing and alarm-indicating systems using polarized circuits.

It is conventional practice to provide separate alarm sensing circuits and alarm indicating circuits that are respectively supervised. Upon the sensing of an alarm condition in the alarm-sensing circuit, the alarm indication circuit can be rendered active.

An object of the present invention is to provide a combined alarm-sensing and alarm-indicating circuit that is polarity sensitive and is automatically pole-changed in response to abnormal current in the circuit.

SUMMARY OF INVENTION

The present invention provides an alarm-sensing and alarm indicating system comprising a circuit which is normally energized from a direct current source. The circuit includes in multiple at least one normally open circuited alarm condition-sensing device and at least one alarm-indicating device. Passage of current through each alarm condition-sensing device is made effective only provided that the circuit is energized with one polarity and passage of current through each alarm indicating device is made effectively only provided that the circuit is energized with the opposite polarity. Pole-changing apparatus is connected to the circuit and is subject to actuation in response to abnormal current in the circuit for changing the polarity of energization of the circuit to activate the alarm-indicating devices.

For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description, taken in connection with the accompanying drawings, while its scope will be pointed out in the appending claims.

FIG. 1 illustrates schematically a supervisory alarm condition-sensing and alarm-indicating system according to one embodiment of the present invention.

FIG. 2 illustrates schematically a supervisory alarm condition-sensing and alarm-indicating system according to another embodiment of the present invention.

FIG. 3 illustrates schematically a combined alarm condition sensing and alarm-indicating circuit according to another embodiment of the present invention.

FIG. 4 illustrates schematically a modification of the form of the invention shown in FIG. 3.

With reference to FIG. 1, an alarm-sensing and indicating system is illustrated as comprising a circuit having wires 10 and 11 which are normally energized from a direct current source of energy having respective positive and negative terminals represented by (+) and (-). The circuit is illustrated as having alarm condition-sensing devices 12 connected between the wires 10 and 11 of the circuit and similarly alarm-indicating devices 13, such as bells, are connected in multiple in the circuit between the wires 10 and 11. The sensing device 12 are made to pass current only when the circuit is energized with one polarity by the inclusion of diodes 14 in series with these devices. Similarly the indicating devices 13 have oppositely poled diodes 15 included in series therewith to permit operation of the alarm indicating devices 13 only when the circuit is energized with the opposite polarity.

Pole-changing in the circuit according to FIG. 1 is accomplished by a two-stage relay K1 that is normally energized to an intermediate position for supervisory purposes, and that is energized to a fully actuated position to pole-change the circuit and apply a reverse polarity to the circuit for activation of the alarm-indicating devices 13.

The circuit according to FIG. 1 is terminated by a resistor 16 so that a normal relatively low level of current flows in the circuit to maintain the relay K1 energized to an intermediate position wherein front contact 17 is closed and back contact 17 is open. More specifically, the circuit by which the relay K1 is energized under these conditions extends from (+) through a reset button 18, fuse 19, winding of relay K1, resistor 16 and back contact 20 of relay K1 to (-). The pole-changing contacts 20 and 21 are not actuated to their picked up positions until the relay K1 is energized with a relatively high current in response to the actuation of an alarm sensing detector 12 to shunt the resistor 16 out of the circuit just described.

A trouble indicating lamp 22 and a trouble indicating bell 23 are normally inactive, and become actuated in case of loss of continuity of the circuit that has just been described to cause the full deenergization of relay K1 and the closure of back contact 17. If this occurs, the lamp 22 becomes energized through the reset button 18 and the back contact 17 of relay K1. Also under these conditions the bell 23 is rendered operable by the energization of a circuit including button 18, back contact 17 of relay K1 and switch 24 in its left-hand position. When these indications have become effective to call to the attention of an operator that a trouble condition exists, the switch 24 can be operated to its right-hand position to silence the bell 23. The lamp 22 remains energized until the relay K1 becomes restored to its intermediate energized state, and when this is done, the bell 23 becomes active to indicate that the switch 24 should be restored to its normal left-hand position.

When the circuit according to FIG. 1 is energized with normal polarity, the bells 13 are silent because of the inclusion of the diodes 15 in series to permit operation only when the circuit is energized with the reversed polarity. The diodes 14, however, are poled for normal polarity of the energization of the circuit so that the actuation of an alarm sensing device 12 to close its contacts becomes effective to shunt the resistor 16 out of the circuit and to cause the relay K1 to be actuated to its fully picked-up position. The circuit including the wires 10 and 11 becomes energized under these conditions with reverse polarity through a circuit extending from (+) including reset button 18, fuse 19, front contact 21 of relay K1, wire 11, diodes 15, bells 13, wire 10 and front contact 20 of relay K1 to (-).

A stick circuit is established to maintain the relay K1 picked-up when it has been actuated in response to an alarm sensing device 12, this circuit including reset button 18, fuse 19, winding of relay K1 and front contact 20 of relay K1. A capacitor 25 is connected across the winding or relay K1 to insure that this relay will be maintained picked up upon its pole-changing operation until establishment of the stick circuit which has been described. As further assurance of operation of relay K1, contact 20 may be adjusted as a make-before-break-before-make contact. The connection of wire 26 to the lamp 22, including in series diode 27, is optional in accordance with the requirements of practice. Without this connection, the lamp 22 becomes energized only under conditions indicating trouble wherein the relay K1 is fully deenergized, while the use of the dotted connection 26 provides that the lamp 22 and the indicating bell 23 also become energized upon an alarm-sensing condition wherein the circuit becomes pole-changed as has been described.

With reference to FIG. 2, another embodiment of the present invention uses separate alarm and supervisory relays K2 and K3, rather than combining the functions of these relays in a two-step relay as has been considered with reference to FIG. 1. The circuit including the alarm-sensing devices 12 and the alarm-indicating devices 13 is the same as has been considered in FIG. 1, and thus it is not considered necessary to describe this circuit in detail. The supervisory relay K3 is normally energized through reset button 30, fuse 31, back contact 32 of relay K2, wire 10, resistor 16, wire 11, back contact 33 of relay K2 and winding of relay K3. This maintains back contact 34 of relay K3 open so that there is no energy applied to trouble indicator lamp 35 and to the trouble bell 36. Should there be loss of continuity in this circuit, the relay K3 will become dropped away, and the closure of back contact 34 of relay K3 would energize the lamp 35 and the bell 36, assuming the switch 37 to be in its normal left-hand position.

In the embodiment shown in FIG. 2, upon the actuation of an alarm-sensing device 12, the relay K2 becomes picked up to pole-change the circuit in accordance with energization of this relay through reset button 30, fuse 31, back contact 32 of relay K2, wire 10, actuated alarm sensor 12, diode 14, wire 11, resistor 38 and winding of relay K2. Contact 33 may be a make-before-break contact. A capacitor 39 is connected across the winding of relay K2 to insure that this relay will be actuated to its fully picked up position for pole-changing the circuit and to establish a stick circuit for relay K2 through reset button 30, fuse 31, front contact 33 of relay K2, resistor 38 and winding of relay K2. The picking up of relay K2 opens the circuit for the supervisory relay K3 at back contact 33, and thus the relay K3 becomes dropped away and the indicators 35 and 36 are rendered active. The circuit including wires 10 and 11 is now energized with reverse polarity upon the picking up of relay K2. This circuit extends from (+), including reset button 30, fuse 31, front contact 33 of relay K2, wire 11, diodes 15, bells 13, wire 10 and front contact 32, to (-). A system as shown in FIG. 2 as well as the systems shown in FIG. 1 and FIG. 3 can be reset to its normal condition by actuation of the reset button 30 after replacement or resetting of the alarm sensing devices 12 that may have been actuated.

With reference to FIG. 3, another embodiment of the invention is illustrated involving the use of silicon-controlled rectifiers to pole-change an alarm sensing and alarm indication circuit in response to the actuation of an alarm-sensing device 12. The alarm sensing devices 12 and the alarm-indicating devices 13 are connected in multiple to the circuit wires 10 and 11 through diodes 14 and 15 in a manner similar to that which has been heretofore described. However, in the circuit according to FIG. 3, no provision has been made for supervision of the circuit, and thus normally no current flows in the circuit but the wires 10 and 11 are connected to respective positive and negative terminals of the source of energy. The circuit wire 10 is connected to the positive terminal of the source of energy through reset button 30, fuse 31, and resistor 50. The circuit wire 11 is connected to the negative terminal of a source of energy through resistors 51 and 52. SCR switches 53 and 54 are provided for pole-changing the circuit in response to the closure of the contacts of an alarm sensing device 12. These switches are normally turned off, and become turned on to pole-change the circuit in response to the actuation of a detector 12 to close its contacts.

The closure of contacts of an alarm sensor 12 of FIG. 3 closes a circuit to charge capacitor 55. This circuit extends from (+), through reset button 30, fuse 31, resistor 50, wire 10, contacts of a device 12, diode 14, wire 11, diode 56 and capacitor 55, to (-). A circuit is also enclosed at this time extending from (+), through reset button 30, fuse 31, resistor 50, wire 10, a sensing device 12, diode 14, wire 11, resistor 51 and resistor 52, to (-). Because of the flow of current in the latter of the above described circuits, the difference in potential across the resistor 52, which is applied between the gate and cathode of SCR 54 is sufficient to turn SCR 54 on. The turning on of SCR 54 causes the circuit wires 10 and 11 to drop to near (-) potential and thus causes a difference in potential across the cathode and gate of SCR 53 to turn this SCR on. The connection of capacitor 55 to the gate of SCR 53 supplies a positive pulse to the gate of SCR 53 at this time. Thus with SCR 53 and SCR 54 both conducting, the alarm-indicating devices 13 are energized because of the reversal of the polarity of energization of the circuit. After the contacts of the sensing devices 12 have been restored to their normally open conditions, the circuit can be reset to its normal condition by actuation of the reset button 53 to restore the SCR 53 and SCR 54 to their normally turned off conditions.

With reference to FIG. 4, a modified form of the invention just described relative to FIG. 3 is illustrated wherein an alarm repeater relay K4 is inserted in the circuit in place of the resistor 50 of FIG. 3, and a supervisory relay K5 is connected in series with a resistor 57 and a diode 58 across the circuit wires 10 and 11 for the purpose of supervising the continuity of the circuit. The relay K5 in combination with resistor 57 is of sufficiently high resistance to limit current flow through the resistor 52 to prevent the turning on of SCR 54 because of the relatively small amount of supervisory current flowing in the circuit. It will be noted that the diode 58 is connected for the energization of relay K5 in response to normal energization of the circuit wires 10 and 11, and that this circuit through the relay K5 is nonresponsive to the polarity of energization under alarm conditions.

Normally the relay K5 is energized to open its back contact 69 and thus prevent the energization of a trouble indicator lamp 60 and a trouble bell 61. If the supervisory relay K5 should become deenergized, because of trouble on the circuit, the closure of back contact 59 provides for the energization of the lamp 60 and the bell 61. The bell 61 can be silenced by the actuation of switch 62 to its right-hand position.

The relay K4 may be substituted for resistor 50 of FIG. 3 (as shown in FIG. 4) if it is desired to have one or more auxiliary contacts actuated under alarm conditions. One use for such a relay could be to energize an indicator 63 upon closure of front contact 64 of relay K4.

Claims

I claim:

1. An alarm-sensing and indicating system comprising a circuit which is normally energized from a direct current source, the circuit including in multiple at least one normally open circuit alarm condition sensing means and at least one alarm indicating means wherein the improvement comprises:

a. means responsive to current polarity for each of the sensing and indicating means for enabling current flow only upon energization of the circuit with said one or the other polarity, respectively; and

b. polarity-changing means connected to the circuit subject to actuation in response to abnormal current in the circuit for changing the polarity of energization of the circuit to activate the indicating devices, comprising: a resistor terminating the circuit, and a relay normally energized at a low level and energized at a higher level to polarity change the circuit in responsive to the actuation of the sensing means and further the relay is operated to an intermediate energization state for supervisory purposes in response to a normal level of current in the circuit and the relay is operated to polarity change the circuit in response to a predetermined high level of current in the circuit.

2. The invention according to claim 1 wherein a holding circuit is provided for maintaining the relay in an activated position until reset after it has been actuated to pole change the circuit in response to actuation of a sensing device.

3. The invention according to claim 1 wherein trouble-indicating means is provided for manifesting an abnormal condition of the circuit.

4. The invention according to claim 1 wherein a second relay is provided for supervisory purposes that is normally energized by the circuit for manifesting continuity in the circuit.

5. An alarm-sensing and indicating system comprising a circuit which is normally energized from a direct source, the circuit including in parallel at least one normally open circuit alarm condition sensing means and at least one alarm-indicating means wherein the improvement comprises:

a. means responsive to the current polarity for each of the sensing and indicating means for enabling current flow only upon energization of the circuit with said one or the other polarity respectively;

b. solid state switching means including at least two silicon-controlled rectifiers responsive to a signal indicative of actuation of an alarm condition-sensing means for polarity changing the circuit, and a resistor capacitor means for delivering said signal to the gate of the silicon-controlled rectifiers in accordance with the current in the circuit for gating the silicon-controlled rectifiers to a conductive state, and

c. trouble-sensing means for checking the continuity of the circuit including a supervisory relay having its winding connected in parallel with the alarm condition-sensing means and means serially coupled to the relay for rendering passage of current through the relay effective to actuate the relay only upon energization of the circuit with said one polarity.

6. The invention according to claim 5 wherein a holding circuit is provided for maintaining the relay in an activated position until reset after it has been actuated to polarity change the circuit in response to actuation of a sensing means.

7. The invention according to claim 5 wherein a relay is provided for supervisory purposes that is normally energized by the circuit for manifesting continuity in the circuit.