WO1987000395A1

WO1987000395A1 - Fault monitoring apparatus and monitoring system therefor

Info

Publication number: WO1987000395A1
Application number: PCT/AU1986/000199
Authority: WO
Inventors: Michael Alan Mcdowell
Original assignee: Industrial Monitoring Systems Pty. Ltd.
Priority date: 1985-07-24
Filing date: 1986-07-18
Publication date: 1987-01-29
Also published as: NZ216954A; AU589669B2; EP0267195A1; AU569223B3; AU6146586A; ZA865526B; GR861919B

Abstract

A fault monitoring apparatus for a multislation pumping system used in irrigation. The pumping system comprises a pump and a series of channels connected to stations 1 - 8 each having an electrically actuable solenoid valve. The apparatus includes a first sensor to monitor the activity of each station, and a second sensor to sense a possible faulty pressure condition of the pump. The second sensor has a pressure sensing transducer located in close proximity to the outlet side of the pump. A control circuit determines the occurence of an actual faulty pressure condition and effects both overriding control of the pump and issuance of an alarm signal in respect thereof. The actual faulty pressure condition is determined when the second sensor senses a possible faulty pressure condition concurrently with the first sensor sensing an active station. A communication means is provided to communicate the status of the system to a remote control station.

Description

"FAULT MONITORING APPARATUS AND MONITORING SYSTEM THEREFOR"

THIS INVENTION relates to a fault monitoring apparatus and monitoring system therefor, a multi-station pumping system ,f of the kind utilised in reticulation systems.

A multi-station pumping system of the type referred to in this specification is defined to comprise:-

a pumping means to supply fluid under pressure;

a plurality of channels arranged into discrete sta¬ tions which are selectively connected to said pumping means to convey said fluid to a plurality of destina¬ tions, each station having a valve means to connect the associated channels to said pumping means when activated and disconnect the same when deactivated;

and controller means having a plurality of control lines each connected to a said station to provide a control signal thereto so as to activate and deacti¬ vate said stations cyclically such that at any one time, at most only one station is activated.

In almost all types of reticulation systems, the supply of water to a station from the pumping means is controlled by a reticulation controller of known design. One example of such a multi-station pumping system is a reticulation sprinkling system used for watering a golf course, wherein different stations are used to water different parts of the golf course. For economy and efficiency, only a single pumping system is utilised which supplies water to f" each of the stations. However, due to the limited capa¬ city of the pump, it is possible only to supply water to one station at a time. To automate and control the opera¬ tion of the pumping system, each outlet has an electri¬ cally operated solenoid valve associated therewith to either open or close the station to the pumping system. Furthermore, by use of a reticulation controller, the solenoid valves of the various stations may be operated directly by the controller for a prescribed time period in a sequential manner. Hence, the reticulation controller may select the first station by opening the solenoid valve associated therewith to the pumping means allowing water to be delivered to the sprinkling system of the station. After a prescribed time period, the reticulation control¬ ler closes the solenoid valve for that particular station and subsequently opens the solenoid valve of the next station, and in a similar manner progressively operates each valve in turn for successive stations until all the stations have been given the opportunity of being connec¬ ted to the pumping system. The controller may then repeat the cycle in accordance with its programmed operation.

A common problem associated with pumping systems of the above kind, is the failure of operation of the solenoid. valve in response to an actuating signal being generated by the reticulation controller. In such instances the pressure in the pumping system outlet can build up to a dangerous level possibly causing permanent damage to the pump and/or rupturing of the pipeline resulting in a substantial loss of water.

Another problem with multi-station pumping systems of this kind is that each valve may have its own pressure trans¬ ducer associated therewith to enable a faulty station to be identified. Due to the relative expense of pressure transducers and the complexities in wiring to connect such valves and transducers to the irrigation controller, which in some cases may be located an appreciable distance away from the valves, such a system tends to be cumbersome, expensive and hence more liable to failure in the monitoring task. In multi-station pumping systems of known designs which have a fault monitoring apparatus to detect a fault condi¬ tion such as over-pressure in the pump outlets, and which disable the pumping system from the active station at which a fault was detected, generally, the pumping system is closed down permanently. If such a system is located within a municipality having a large number of reserves incorporating the pumping systems of the kind described, a substantial period of time may elapse before a maintenance check is conducted for the particular pumping system. Thus, upon a fault occurring and the pumping system being disabled, several weeks may elapse before a maintenance check is conducted at the pumping system before the fault is detected.

It is an object of the present invention to provide a fault monitoring apparatus which is capable of sensing, a fault condition in a multi-station pumping system, pro¬ viding a sensorially perceptible signal in respect there¬ to, and disabling the pumping system from the station at which the fault was detected.

It is a further object of the present invention to provide a fault monitoring apparatus which is cost effective and efficient when compared with prior art designs.

It is a preferred object of the present invention to provide a fault monitoring apparatus which is discrete from the control means of a multi-station pumping system as herein defined and hence can be fitted as an adjunct to existing irrigation controllers of various designs.

It is another preferred object of the present invention to provide a monitoring apparatus for a multi-station pumping system which can communicate remotely with a central control to enable remote monitoring of the status of the pumping system. In accordance with one aspect of the present invention, there is provided a fault monitoring apparatus for a multi-station pumping system of the type herein defined, said apparatus comprising:-

a first sensing means to sense the activity of each station;

a second sensing means to sense a possible faulty pressure condition of the pumping system locally of the pumping means; and

a control means to monitor said sensing means, determine the occurrence of an actual faulty pressure condition, and both effect overriding control of the operation of said pumping means and issue an alarm signal in respect of said actual faulty pressure condition;

wherein said possible faulty pressure condition is determined by said second sensing means sensing the fluid pressure of said system between the output of said pumping means and the inputs of said valve means, and said actual faulty pressure condition is determined by said control means when said second sensing means senses said possible fault condition concurrently with said first sensing means sensing an active station.

Preferably, said control means provides an indication of the particular station subjected to. said actual fault condition.

Preferably, said apparatus includes storage means to store status information pertaining to said apparatus and com¬ munication means to communicate said status information to a remote control station. Preferably, said control means is adapted to effect said overriding control by disabling the operation of said pumping means for an active station in respect of which a said actual faulty pressure condition is detected, and enabling the operation of said pumping means for an active station in respect of which a said actual faulty pressure condition is not detected.

Preferably, said control means includes scanning means to iteratively monitor the activity of said stations and latching means to latch said scanning means to an active station and generate a common active station signal in response thereto until said active station is deactivated.

Preferably, said apparatus includes a third sensing means to sense the moisture of the environment in the proximity of said destinations and . said control apparatus being adapted to effect overriding control of the operation of said pumping means whilst the station for said destination is active in response to the moisture condition sensed at said destination.

Preferably, said apparatus includes a fourth sensing means to sense said fluid pressure during the time that one particular station is active, and dampening means to dampen the response of said fourth sensing means to tran¬ sitory fluctuations in said 'fluid pressure, whereby said control means is adapted to monitor said fourth sensing means and provide an indication as to the efficiency of said pumping means.

In accordance with another aspect of the present inven¬ tion, there is provided a fault monitoring system for monitoring a network of independent multi-station pumping systems of the kind herein defined comprising: a central control station and a series of distributed pumping sys- terns of the kind herein defined each having a communica¬ tion means to communicate with said control station, a local fault monitoring apparatus as defined in the preced¬ ing aspect of the invention to monitor one or more local conditions, and a storage means to store the status of said conditions thereat; wherein said communication means is adapted to communicate said status to said central control station.

The invention will be better understood in the light of the following description of several embodiments thereof. The description is made with reference to the accompanying drawings wherein:-

Fig. 1 is a schematic diagram of a multi-station pumping system in accordance with the first embodi¬ ment of the invention;

Fig. 2 is a block diagram of the fault monitoring apparatus in accordance with the first embodiment of the invention;

Fig. 3 is a, block diagram of the monitoring system in accordance with the second embodiment of the inven¬ tion;

Fig. 4 is a block diagram of the central monitoring station in accordance with the second embodiment; and Fig. 5 is a block diagram of a pumping station in accordance with the second embodiment.

The first embodiment is directed towards a fault monitor¬ ing apparatus used to monitor a fault condition at a multi-station pumping system in the form of a reticulation sprinkling system which is controlled by a reticulation controller.

With reference to Fig. 1, a multi-station pumping system 11 is shown in ^' the form of a reticulation sprinkling system which generally consists of a pumping means 12 and a series of channels 13 connected thereto which deliver water supplied by the pumping means to respective stations numbered 1 to 8. In a multi-station pumping system of this kind, each station is provided with valve means in the form of an electrically operated solenoid valve 14 in series with the station connected thereto, each valve being operable to selectively connect a station to the channel 13 of the pumping system. By selectively operating the valves 14 it is possible to utilise a pump¬ ing means having a capacity sufficient to supply the demands of a single station at any one time, thereby reducing the expense involved in utilising a pump of sufficient capacity to supply all stations at once.

The selective operation of the solenoid valves is con¬ trolled by a controller means in the form of a reticula¬ tion controller 15 of which a variety of designs are marketed. The reticulation controller 15 provides a control signal in the form of an actuating voltage to a solenoid valve in accordance with the controlling program thereof. This program is arranged to issue an actuating voltage to only one solenoid valve at any one time via a control line 16 thereof. Furthermore, the program issues the actuating voltage sequentially to each station in turn, each having the actuating voltage supplied for a prescribed period of time before the program switches to the next station. Upon completion of the sequence, the program may repeat the cycle after a prescribed time, generally referenced to a 24 hour clock.

In a typical reticulation controller and solenoid valve, an actuating voltage of approximately 24 volts AC is used to actuate the solenoid, which upon receipt thereof opens the valve and so enables water from the pumping means to flow through to the station connected thereto, in a rela¬ tively unimpeded manner. To monitor the fault condition of the pumping system, a fault monitoring apparatus 18 is provided, which generally comprises a first sensing means 21, a second sensing means 22 and a control means 23.

The first sensing means comprises a station interface means having a series of station monitoring inputs 19 connected to each of the control lines 16 of the reticula¬ tion controller 15 and conditioning means 26 associated with each input. The station monitoring inputs are con¬ nected such that there is a one-to-one correspondence between an input and the control line of a station. The conditioning means 26 has a series of station monitoring outputs 27 corresponding to said station monitoring inputs 19 which in turn are connected to the control means 23. The first sensing means 21 is designed to sense the ac¬ tivity of each of the control lines 16 of the reticulation controller 15 and thus provides an indication of which station is-active, i.e. a station which has its associated solenoid valve subjected to an actuating voltage from the reticulation controller 15. Moreover, the conditioning means 26 is designed to generate a separate active station signal for a station monitoring output 27 corresponding to a particular station in response to the detection of an activating control signal issued by the controller to the particular station.

The second sensing means comprises a pressure sensor 17 provided in series with the pump channels 13 and in close proximity to the pumping means 12, and an isolating inter¬ face means 36 which is connected between the pressure sensor 17 and control means 23 to isolate the output of the sensor from the control means. Moreover, the sensor is disposed between the output of the pumping means and the inputs of the valves 14. The pressure sensor is a transducer of known type and provides an electrical output signal indicative of the pressure at the pump outlet. Moreover the electrical output signal denotes a possible fault signal in the form of an electrical current which is output at approximately 12 milli-amps in response to the pressure sensor 17 sens¬ ing an abnormal pressure at the pump outlet.

The pressure sensor 17 upon sensing an abnormal condition generates a possible fault signal which is subsequently applied to the isolating interface means 35 via the sensor output line 20. The isolating interface means effectively isolates the possible fault signal from the control means 23 and generates an isolated possible fault signal which is subsequently applied to the control means for moni¬ toring and possible control of the operation of the pump¬ ing means.

The control means 23 is described in more detail later but generally monitors both the first and second sensing ^"means and determines the occurrence of an actual faulty pressure condition. Upon determining such an occurrence, the control means is adapted to issue an actual fault signal to the pumping means via the output line 24. This fault signal is arranged to effect overriding control of the pumping means by disabling the operation thereof in res¬ ponse to the concurrent detection of a possible fault condition as sensed by the second sensing means 22 and the sensing of an active station by the first sensing means 21.

Coinciding with the issue of an actual fault signal, the control means 23 also generates an alarm signal at a visual display 25 connected thereto. This signal is arranged to provide an indication of which station was subject to the fault condition. The control means includes storage means 101 and communi¬ cation means 52. The storage means 101 is in the form of an electronic memory device and is intended to store status information pertaining to the status of the pumping system, for example the -occurrence and location of a. fault condition etc. The communication means 52 is provided with a transmitter means 105 and receiver means 107 which are connected via an appropriate transmission medium, such as a telephone exchange line 53, to a remote control station. The communication means is described in more detail in the second embodiment but is generally adapted to communicate the status information of the pumping system to the_. remote control station in response to the control means detecting an actual faulty pressure condi¬ tion or interrogation by the station.

The fault monitoring apparatus .also has a third sensing means 103 in the form of a moisture sensor connected to the control means 23, which senses the moisture content of the ground subjected to sprinkling by the pumping system. A plurality of such moisture sensors may be distributed amongst the stations and can provide an indication of which stations are required to be activated by the con¬ troller means 15 for watering. Thus when the moisture content for a particular station which is about to be or has been activated is above a pre-determined limit, the moisture sensor provides a moistur'e signal to the control means which in turn may effect overriding control of the operation of the pumping means by de-activating the same for that particular station.

A fourth sensing means 109 in the form of a further pres¬ sure sensor and a dampening means 111 is also provided for connection to the control means 23. The further pressure sensor is connected in series with one particular station to sense the fluid pressure therefor during the time the particular station is active. The output of the further pressure sensor is in turn connected to the dampening means 111 which is adapted to dampen the response of the sensor to transitory fluctuations in the fluid pressure. Accordingly the dampening means 111 generates a dampened pressure signal to the control means, which signal can provide an overall indication of the efficiency of the pumping means. Thus the control means can process the signal as status information of the pumping system and store this information at the storage means thereof.

Now - describing the fault monitoring apparatus in more detail, particular reference is made to Fig. 2 of the drawings.

The fault monitoring apparatus 18 has a series of external wiring connectors 19 individually wired to the eight solenoid control lines 16 from the reticulation controller 15, .marked 1 to 8. Each of the connector lines 19 form the station monitoring input of the first sensing means 21, and are connected to eight dedicated solenoid input circuits 26, each corresponding to a particular connector line. Each solenoid input circuit 26 forms a signal conditioning means to sense a possible 24 volt AC activating control signal, output by the reticulation controller 15. Each input 26 includes a rectifier and filter to convert the applied AC signal to a DC signal, which is then resistively divided to suitably attenuate the signal for application to a digital inverting buffer (not shown). The inverting buffers each provide a station monitoring output 27 at which a separate active station signal is generated in response to the detection of an activating control signal at the station thereof. Thus, an inverting buffer provides a logic "high" signal if the corresponding input to the input circuit 26 is not active, and a separate active station signal in the form of a logic "low" signal if it is active. The input circuit in the present embodiment is arranged to sense an active signal if an input AC voltage of more than 10 volts is detected on the input line 19.

The station monitoring output 27 of each input circuit 26 is subsequently connected to a scanning means and latching means 28 and an alarm means 29 which both form part of the control means 23.

The scanning means is intended to iteratively monitor the activity of the station monitoring outputs 27 and the latching means operates to latch the scanning means to a station monitoring output at which a separate active station signal is output, and generate a common active station signal in response thereto until the separate active station signal ceases.

The scanning means and latching means - 28 comprise-- a clocking means in the form of an oscillating means 30, and switching means in the form of a counting means 113 and multiplexing means 115.

The oscillating means 30 is arranged to provide a clocking signal along line 31 to the counting means 113 in response to an enabling output signal provided on line 32 connected from the output of the multiplexing means. The output signal of the multiplexing means 115 provided on the output line 32 in fact is the common active station signal and is derived from one of the station monitoring outputs 27 as selected by the counting means. That is, each of the station monitoring outputs 27 are respectively connec¬ ted to the input lines 33 of the multiplexing means. These inputs are then connected in sequence to the output line 32 of the multiplexing means 115 in accordance with a selector signal output by the counting means to the multi¬ plexing means.

The selector signals of the counting means are sequen¬ tially clocked by the application of the clocking signals along line 31 thereto. Thus, when the oscillating means 30 is enabled, the counting means is clocked causing the multiplexing means to sequentially connect the input lines 33 to the output line 32. Moreover, when a logic "high" is provided on a station monitoring output line 27 selec¬ ted by the counting means and multiplexing means, in¬ dicating an inactive station, a logic "high" enabling output signal is provided on line 32 which causes the oscillating means to be enabled via line 34 and hence causes the counting, means to increment so as to cause the multiplexing means to select the next station monitoring output line 27 connected thereto, and so on. Thus sequen¬ tial operation will continue until a separate active station signal in the form of a logic "low" signal is detected on a selected station monitoring output. Conse¬ quently a common active station signal in the form of a logic "low" signal will be provided on the output line 32 indicating an active station, causing the oscillating means to be disabled and thus locking the counting means.

Thus the application of the disabling signal to the oscil¬ lating means 30 will be sustained, latching the appro¬ priate active station monitoring output to the control means 23. Subsequently, this output will only be delat- ched from the scanning means when it becomes- inactive, i.e. when the state of the particular input line 33 chan¬ ges back to a logic "low" signal, thereby enabling the oscillating means 30 and causing incrementation of the counting means and sequencing of the multiplexing means once more.

The fault monitoring apparatus 18 is also provided with an isolating interface means 35 which receives its input via line 20 from the pressure sensor 17 to form the second sensing means 22. In view of the pressure sensor 17 providing a possible fault output signal in the form of an electrical current, a current loop interface is required which enables an opto isolator to be used as the isolating interface means 35 and so isolates the input line 20 from the output line 38 thereof. The opto isolator (not shown) receives its biasing voltage from the output of a fault detecting means 36, described hereinafter, via feed back line 37. Accordingly an isolated possible fault signal is generated at the output line 38 in response to receipt of a possible fault signal from the pressure sensor 17, when the opto isolator is correctly biased via feedback line 37.

The fault detecting means 36 also forms part of the con¬ trol means 23 and derives inputs from both the opto isola¬ tor output, via line 38, and the multiplexing means out¬ put, via line 39.

Accordingly, the fault detecting means 36 receives an isolated possible fault signal via line 38 and/or a common active station signal via line 39, when such signals are generated.

The fault detecting means is essentially in the form of a timer which generates an actual fault signal in response to the concurrent application of an isolated possible fault signal and common active station signal thereto.

Both lines are connected to a reset input of the fault detecting means via input line 40. Consequently, the fault detecting means 15 is continuously reset in the absence of either an isolated possible fault signal or a common active signal at lines 38 and 39 respectively, i.e. in response to the assertion of a logic "high" signal on either line. Thus to accord with the logic "high" signal produced by the multiplexing means at input line 39 in the absence of a common active signal, the opto isolator produces a logic "high" signal at the input line 38 in the absence of a fault condition sensed by the pressure sensor 17.

This continuous resetting of the fault detecting means suppresses the generation of an actual fault signal at the output 41 thereof until the concurrent application of the isolated possible fault signal and common active signal to the reset input, whereupon the fault detecting means is primed to generate the actual fault .signal.

Whilst being reset, the fault detecting means 36 produces a logic "low" at its output line 41. This output is subsequently fed back to the isolating interface means 35 along the feedback line 37 and inverted to provide the biasing voltage for the opto isolator. Thus the output of the fault detection means 36 is only set to a logic "high" in response to the generation of an actual fault signal. The output of the fault detection means 36 upon being changed to a logic "high" causes the bias voltage applied to the opto isolator via line 37, to be removed therefrom, thereby latching the isolating interface means output, at line 38, to a logic "low" condition. Consequently, the fault detecting means 36 can only be reset as a result of the input circuit 26 detecting an inactive input corres¬ ponding to latched station monitoring output causing the common active station signal to cease.

The fault detecting means is provided with a time delay means (not shown) whereby a prescribed time delay is initially imposed on the concurrent detection of an isola¬ ted possible fault signal and a common active station signal at the reset input 40 to accommodate transient possible fault signals generated by the pressure sensor 17 due to possible fluctuations in water flow produced by the pumping means and delays in attaining pressure after ini¬ tiation of an activating control signal from the reticula¬ tion controller 15. This delay may be set to 3 to 6 seconds, wherein a change at the fault detecting means output 41 to a logic "high", i.e. generation of the actual fault signal, will only be effected if the applied logic "low" signal at the reset input is still present, i.e. if the possible faulty condition and the active input are still sensed after the prescribed delay.

The fault- timing means output 41 is also connected to a pump switching means in the form of a motor stop relay 42, via output line 24, and to the alarm means 29, via input line 44. The motor stop relay 42 functions to control the operation of the pumping means 12 by enabling or disabling the. same. The pump stop relay 42 is connected to the fault detecting means output line 41 in a manner such that when a logic "low" signal appears on the line 41, the relay contacts are arranged to enable operation of the pumping means 12, and when a logic "high" signal appears, i.e. an actual fault signal, the relay contacts are swit¬ ched to disable operation of the pumping means.

The alarm means 29 receives each of the eight station monitoring outputs 27 via input lines 45. The alarm means 29 generally consists of first gating means 81, second gating means 83 and buffer means 85. The first gating means 81 is connected to each of the inputs 45 and provi¬ des a series of corresponding first gating outputs 87 which in turn feed the second gating means 83. The second gating means 83 is in the form of a clocked register and is provided with a series of second gating outputs 89 corresponding respectively to the first gating outputs 87. The second gating outputs 89 are connected in turn to the buffer means 85 which is in the form of an inverting buffer itself having a series of corresponding buffer outputs which are connected via the latch circuit output lines 46 to a visual display 47. The first gating means 81 is segmented to obtain one input from input line 45 and another input from a feedback line 91 derived from the respective buffer output line 46 of the inverting buffer 85, for each segment. The clocked register has strobing means (not shown) and receives a strobing signal via input line 44 derived from the fault detecting means output line 41. Thus signals applied at the first gating outputs to the inputs of the clocked register are strobed via the inverting buffer to actuate the visual display by generat¬ ing an alarm signal in response to the fault detecting means 36 detecting an actual faulty pressure condition and asserting a logic "high" signal i.e. actual fault signal at the output line 41.

The visual display 47 consists of a series of light emitt¬ ing diodes (LED's) connected one to each buffer output line 46 of the inverting buffer such that each LED corres¬ ponds to a station input (1 to 8) and the lighting of the same indicates the detection of an actual faulty pressure condition therewith, whilst that particular station was active. Accordingly, upon strobing the clocked register 83, any input applied to the same from the first gating means, which is indicative of an active station will consequently cause the LED corresponding to this station to be activated.

The feed back lines 91 connected to the first gating means 81, and which are fed back from the buffer outputs 46, are provided to maintain latching of an activated LED in the active condition. This is achieved by latching the cor¬ responding first gating output 87 of an activated LED to the activating state by feeding back the activated alarm signal to the input of the first gating means causing the activating signal of the first gating output to be sus¬ tained.

The alarm means 29 derives another input 48 from a master control in the form of a reset switch 49. The reset switch 49 is operated manually by a push button switch (not shown) or automatically upon power up of the appara¬ tus to provide a reset signal to the clocked register 83. In response to this reset signal, the clocked register resets its outputs to deactivate the visual display 47.

The visual display 47 is also provided with an output line 50 connected to an alarm extension relay 51, whereby the relay may be immediately actuated in response to the generation of an alarm signal and the activation of a LED within the visual display 47. The alarm extension relay consequently may effect operation of communication means 52 connected thereto, which upon being activated by actua¬ tion of the alarm extension relay 51, is capable of com¬ municating the status of the fault monitoring apparatus to a remote location, for example by way of the telephone exchange line 53.

The operation of the fault monitoring apparatus will now be described. The fault monitoring apparatus 18 directly monitors up to eight separate 24 volt AC solenoid circuits as provided by the typical reticulation controller^' 15. The first sensing means 21 by way of the scanning means and latching means 28, continually scans the activity at each of the solenoid control lines 16 to sense an active input, i.e. one with more than 10 volts AC appearing thereon. Once an active input is located, the separate active station output therefor is latched for monitoring and use by the fault detecting means 35 and the alarm means 29, by disabling the oscillating means 30 of the circuit. Concurrently with this, the fault detecting means 35 senses whether a possible fault signal is provi¬ ded by the pressure sensor 17, to detect a possible fault condition at the pump outlet 13. If a fault condition is detected co-incidentally with the activation of a station input, the time delay means is activated to provide a prescribed delay of some 3 to 6 seconds before the fault detecting means 36 determines whether to issue an actual fault signal indicative of an actual fault condition. If, after the prescribed time delay, an actual fault signal is issued by the fault detecting means 36, the pump stop relay 42 is actuated to disable the pumping means 12 and the alarm means is strobed to produce an alarm signal to activate an LED corresponding to the particular station which is active. This LED remains active until the reset switch 49 is activated to reset the visual display 47. In addition, the pump stop relay continues to disable the pumping system 12 until such time as the output signal of the fault mask timer reverts to the logic "low" state indicating the absence of a fault condition or the absence of an aςtive station. During the time that an actual faulty pressure condition is sensed by the isolating interface means 35 and the actual fault signal is issued by the fault detecting means 36, the output 41 is latched to the "low" state until the station input which is lat¬ ched to the control means is deactivated.

The second embodiment of the invention is directed towards a particular application of the monitoring apparatus described in the previous embodiment as used in a network of independent multi-station pumping systems of the type previously defined.

As shown at Figs. 3, 4 and 5 of the drawings, a monitoring system 61 consists of a central remote control station 62 interconnected to a series of distributed pumping systems 63. The central station 62 consists of a main computing means 64 having a peripheral device 65 in the form of a printer and/or visual display unit. The computing means 64 is further provided with a communications interface 66 which connects to a telephone exchange line via connector 67.

The multi-station pumping system is of the kind described in the preceding embodiment and is shown at Fig. 5, where¬ in the system comprises: a reticulation controller 68 having a series of output lines 69 operatively connected to a series of solenoid valves associated with each sta¬ tion connected to the pumping means (not shown), a fault monitoring apparatus 70 deriving its monitor inputs 71 from the output control lines 69 of the reticulation controller, a communication means 72 actuated by the alarm extension relay 51 described in the preceding embodiment, and a local computing means 73 connected to both the fault monitoring apparatus 70 and the communication means 72.

The local computing means 73 includes a storage means (not shown) to store status information including the status of fault conditions detected at the pumping station. These fault conditions may not necessarily be limited to the fault conditions monitored by the fault monitoring appara¬ tus described in the preceding embodiment. For example, a range of fault conditions may include: high and low pres¬ sure sensing at the pump outlets, pump efficiency and soil condition as previously described, phase failure appli¬ cable to the electrically operated pumping means, mains failure and restoration, the arrival and departure of a maintenance crew to the pumping system, vandalisation of the pumping system, etc. In addition, the local computing means 73 may include an actuating means to actuate the communication means 72 immediately in response to the detection of one or more fault conditions at the pumping system. The communication means is provided with a two way com¬ munication input/output line connected to the telephone exchange line 74. In such an arrangement, each pumping system has its own dedicated telephone number together with the central control station so that communications between the central control station and any pumping sta¬ tion are transmitted and received via the telephone ex¬ change line. Accordingly, the communications interface 66 of the central control station and the local computing means 73 and communication means 72 of a pumping system 63 have transmitter means and receiver means (not shown) to receive and transmit data according to the status of the pumping system. To ensure accurate communication of data, the communications protocol is arranged to proceed with handshaking and parity checks in accordance with conven¬ tional design practice. The central control station, can also be provided with a facility of interrogating each pumping system on a routine basis to ascertain correct operation thereof, whereby an interrogatory signal is transmitted by the central control station to a particular pumping system and upon receipt of the same the pumping system transmits its status information.

An obvious• advantage of the present embodiment is that fault conditions can be transmitted to a central station immediately upon their occurrence, and thus maintenance crews can be despatched to the particular pumping system reporting the fault within a relatively short time of the fault being detected by the fault monitoring apparatus. Furthermore, the time spent in maintenancing the various stations within a municipality, for example, is greatly reduced due to the almost instantaneous reporting of fault conditions.

It should be appreciated that the scope of the present invention is not limited to the scope of the particular embodiments herein described.

Claims

THE CLAIMS defining the invention are as follows:-

1. A fault monitoring apparatus for a multi-station pumping system of the type herein defined, said apparatus comprising:-

a first sensing means to sense the activity of each station;

2. A fault monitoring apparatus as claimed at claim 1 wherein said control means provides an indication of the particular station subjected to said actual fault condi¬ tion.

3. A fault monitoring apparatus as claimed at claim 1 or 2, wherein said apparatus includes storage means to store status information pertaining to said apparatus and com¬ munication means to communicate said status information to a remote control station.

4. A fault monitoring apparatus as claimed at any of the preceding claims, wherein said control means is adapted to effect said overriding control by disabling the operation of said pumping means for an active station in respect of which a said actual faulty pressure condition is detected, and enabling the operation of said pumping means for an active station in respect of which a said actual faulty pressure condition is not detected.

5. A fault monitoring apparatus as claimed at any of the preceding claims, wherein said control means includes scanning means to iteratively monitor the activity of said stations, and latching means to latch said scanning means to an active station and generate a common active station signal in response thereto until said active station is deactivated.

6. A fault monitoring apparatus as claimed at any of the preceding claims, wherein said apparatus includes a third sensing means to sense the moisture of the environment in the proximity of said destinations, and said control appa¬ ratus being adapted to effect overriding control of the operation of said pumping means whilst the station for said destination is active in response the moisture condi¬ tion sensed at said destination.

7. A fault monitoring apparatus as claimed at any of the preceding claims, wherein said apparatus includes a fourth sensing means to sense said fluid pressure during the time that one particular station is active, and dampening means - -

to dampen the response of said fourth sensing means to transitory fluctuations in said fluid pressure, whereby said control means is adapted to monitor said fourth sensing means and provide an indication as to the effi¬ ciency of said pumping means.

8. A fault monitoring apparatus as claimed at any of the preceding claims, wherein said first sensing means com¬ prises a station interface means having a series of sta¬ tion monitoring inputs derived from the control lines of said controller means such that a one-to-one correspon¬ dence is provided between an input and the control line of a station, and conditioning means associated with each input and having a series of station monitoring outputs corresponding to said inputs, whereby a separate active station signal is generated at an output corresponding to a particular station in response to the detection of an activating control signal issued by said controller to said particular station, said separate active station signal being .provided for monitoring by said control means.

9. A fault monitoring apparatus as claimed at any of the preceding claims, wherein said second sensing means com¬ prises a pressure sensor to provide a possible fault signal denoting a said possible fault pressure condition when said fluid pressure is outside a range of prescribed parameters, and an isolating interface means to provide an isolated possible fault signal for monitoring by said control means.

10. A fault monitoring apparatus as claimed at any of the preceding claims as dependent upon claims 5 and 8, wherein said scanning means and said latching means comprise clocking means to generate a periodical clocking signal in the absence of said common active station signal, and switc ιny means to selectively receive said conditioning means outputs of successive stations sequentially in response to successive clocking signals and generate said common active station signal upon detecting a separate active station signal on a received output, whereby the generation of said clocking signal is disabled in response to the generation of said active station signal to provide said latching.

11. A fault monitoring apparatus as claimed at any of the preceding claims as dependent upon claims 5 and 9, wherein said control means includes fault detecting means to generate an actual fault signal in response to detecting said actual faulty pressure condition, said fault de¬ tecting means adapted to receive said isolated possible fault signal and said common active station signal and generate said actual fault signal only when said isolated possible fault signal and said active station signal are concurrently detected.

12. A fault monitoring apparatus as claimed at claim 11, wherein said fault detecting means includes time delay means whereby a prescribed time delay is imposed when said isolated possible fault signal and said common active station signal are concurrently detected such that said actual fault signal is only generated if said concurrently detected signals are still received- after said prescribed time delay.

13. A fault monitoring apparatus as claimed at claim 11 or 12, wherein said fault detecting means in the absence of either said isolated possible fault signal or said common active station signal is continually reset to suppress the generation of said actual fault signal, and said isolated possible fault signal is latched to said fault detecting means upon the generation of said actual fault signal, whereinafter said fault detecting means can only be reset by the absence of said common active station signal .

14. A fault monitoring apparatus as claimed at claim 13, wherein said fault monitoring means incorporates feed back to latch said isolated possible fault signal thereto.

15. A fault monitoring apparatus as claimed at any of the preceding claims as dependent upon claim 11, wherein said actual fault signal actuates a pump switching means to switch so as to deactivate said pumping means.

16. A fault monitoring apparatus as claimed at any of the preceding claims as dependent upon claims 2, 8 and 11, wherein said control means includes an alarm means to generate said alarm signal having a series of inputs derived from said conditioning means outputs, whereby said alarm signal is generated in response to the concurrent generation of a said separate _m active station signal and said actual fault signal, said alarm signal denoting the particular station in respect of which said separate active station signal is generated.

17. A fault monitoring apparatus as claimed at claim 16, wherein said alarm signal after being generated for a particular- station is latched until said alarm means is reset by a master control .

18. A fault monitoring apparatus as claimed at claim 17, wherein said alarm means comprises first gating means at said inputs thereof having a series of first gating out¬ puts corresponding to said inputs, second gating means adapted to receive said first gating outputs and having a series of second gating outputs corresponding to said first gating outputs, and buffer means adapted to receive said second gating outputs and having a series of buffer^" outputs corresponding to said second gating means, said buffer outputs being fed back to the corresponding inputs of said first gating means, and said second gating means having strobing means to strobe signals generated at said first gating outputs to said second gating outputs in response to the generation of said actual fault signal, and said buffer means adapted to generate and latch a said alarm signal at a said buffer output in response to a signal generated at a corresponding said second gating output, whereby a said first gating output signal is generated in response to the generation of a corresponding separate active station signal or a corresponding alarm signal fed back thereto.

19. A fault monitoring apparatus as claimed at any of the preceding claims as dependent upon claim 3, wherein said communication means is provided with transmitter means to transmit said status information to said remote control station in response to the generation of a said alarm signal.

20. A fault monitoring apparatus as claimed at any of the preceding claims as dependent upon claim 3, wherein said communication means is provided with receiver means to receive a remote control signal from said remote control station, whereby said remote control signal either activa¬ tes said transmitter means to transmit said status to said remote control station, and/or activates said control means to effect overriding control of the operation of said pumping means.

21. A fault monitoring apparatus substantially as herein described with reference to the accompanying drawings mutatis mutandis.

22. A fault monitoring system for monitoring a network of independent multi-station pumping systems of the kind herein defined comprising: a central control station and a series of distributed said pumping systems each having a communication means to communicate with said control station, a local fault monitoring apparatus as claimed at any of the preceding claims to monitor one or more local conditions, and a storage means to store the status of said conditions thereat; wherein said communication means is adapted to communicate said status to said central control station.

23. A fault monitoring system as claimed at claim 22, wherein said communication means may be actuated in res¬ ponse to the detection of a fault condition and/or in response to an interrogatory signal received from said central control station.

24. A fault monitoring system substantially as herein described with reference to the accompanying drawings mutatis mutandis.