GB2155673A

GB2155673A - Improvements in or relating to meters

Info

Publication number: GB2155673A
Application number: GB08503316A
Authority: GB
Inventors: Anthony Morgan
Original assignee: THORN EMI DYNATEL Ltd
Current assignee: THORN EMI DYNATEL Ltd
Priority date: 1984-02-09
Filing date: 1985-02-08
Publication date: 1985-09-25
Also published as: GB8403457D0; GB2155673B; GB8503316D0

Abstract

An inductive electricity meter or reversible fluid flow meter has a disc 1 whose rotation occasions photocells 2, 3 to produce output signals from which a control unit 5 generates pulses each corresponding to a revolution of disc 1. The control unit 5 also divides up the pulses according to the direction of rotation and directs them towards either forward counter 6 which records consumption of electricity or reverse counter 15 which records fraudulent reversal of disc 1. The meter has two single-pulse stores 14 and 20 to ensure that the amounts registered by counters 6 and 15 are maintained correct even when spurious single-reverse pulses occur, caused by inherent design characteristics of the meter. <IMAGE>

Description

SPECIFICATION Improvements in or relating to meters This invention relates to meters in which consumption of a quantity is represented by rotation of a rotor in one direction. It is particularly related to rotating disc induction electricity meters including multi-tariff meters although it might find application in fluid flow meters in which flow in one or other direction provides one or other direction of rotation of a rotor.

In an electricity meter the rotation may be counted by conventional mechanical register but it is proposed also to provide a count of electrical pulses generated by rotation of the disc which is advantageous for multi-tariff meters.

It is known for British Patent Specification No. 1,363,699 to determine the direction of rotation of the rotor of a fluid flow meter by the use of two responders closer than 180 apart on the periphery of a rotor. This may be adapted to determine the direction of rotation of the disc of an electricity meter to show reverse rotation which might be fraudulent. However it has been found that this is not a reliable indication of fraud.

An object of this invention is to provide an improved arrangement of a meter.

An object of the invention is to provide a meter which produces a reliable indication of consumption even if spurious reverse rotation occurs.

According to the invention there is provided a meter including: a rotor member; means for providing first pulses indicative of rotation of the rotor member in a first direction and second pulses indicative of rotation of the rotor in a second direction; a first counter for storing a cumulative count of the pulses indicating rotation in the first direction; a second counter for storing cumulative count of the pulses indicating rotation in the second direction; means for monitoring for a predetermined number of pulses which represent rotation in the second directon, such pulses (i) following one or more pulses representing motion in the first direction and (ii) being followed directly by one or more pulses representing motion in the first direction; and means for inhibiting the passage of a predetermined number of pulses to at least one counter, the inhibiting means being operable in response to the monitoring means.

Preferably, the meter includes means for withholding, from the second counter, a predetermined number of pulses which represent rotation in the second direction, such pulses (i) following one or more pulses representing motion in the first direction and (ii) being followed directly by one or more pulses representing motion in the first direction.

In one example, the withholding means comprises storage means of a capacity to hold the predetermined number of pulses and located in the path to the second counter.

Preferably, the meter also comprises means for restraining, from the first counter, a specified number of pulses which represent rotation in the first direction, the restraining means being actuable in response to occurrence of a predetermined number of pulses which represent rotation in the second direction, such predetermined number of pulses (i) following one or more pulses representing motion in the first direction and (ii) being followed directly by one or more pules representing motion in the first direction.

In one example, the restraining means comprises storage means of a capacity to hold the specified number of pulses, the storage means being actuated by switching it into the path to the first counter.

Preferably the specified number relating to the restraining means corresponds to the predetermined number relating to the withholding means.

Preferably the restraining means is actuable by operation of the withholding means. Thus for example operation of the withholding means may produce a signal which effects switching of storage means into the path to the first counter.

In one preferred form of the invention, the meter is arranged to have one store which can function as both the withholding means and the restraining means.

The meter may be an induction electricity meter in which motion in the second direction is provided by fraudulent reversal of the disc. Where one count is provided per 360 rotation of the disc the predetermined number of reverse counts ignored is one.

It has been found that a problem in simply counting reverse rotation pulses to determine fraudulent reversal of an electricity meter is that spurious pulses can be produced since the disc tends to run backwards when the load is removed; clearly, a spurious pulse might not be produced each time a load is removed, but depends on the position of the disc upon load removal. Another cause of spurious pulses is juddering of the disc which tends to occur when the load is very light. These two causes of spurious pulses are inherent in the conventional design of the meter. The reverse rotation produced in these two ways should generally not exceed one revolution so that, for a system in which one pulse is produced per revolution, a single reverse count may be spurious and hence not due to fraudulent reversal but two or more reverse counts are almost certainly due to fraud.

Preferably, the meter includes means to determine the direction of rotation of the rotor member and means to pass pulses, derived from rotation of the rotor member, towards the first counter or the second counter in accordance with the output from the direction-determining means.

According to another aspect, the present invention provides a method of measuring the consumption of a quantity, the method comprising: applying a meter with a rotor member such that the rotor member is rotated in response to flow of the quantity; providing first pulses indicative of rotation of the rotor member in a first direction and second pulses indicative of rotation of the rotor in a second direction; storing a cumulative count of the pulses indicating rotation in the first direction; storing cumulative count of the pulses indicating rotation in the second direction; monitoring for a predetermined number of pulses which represent rotation in the second direction, whereby these pulses (i) follow one or more pulses representing motion in the first directon and (ii) are followed directly by one or more pulses representing motion in the first direction; and, when a predetermined number of such pulses are detected, inhibiting the passage of a predetermined number of pulses to at least one counter.

Preferably, the method also comprises withholding, from the second counter, a predetermined number of pulses which represent rotation in the second direction, whereby these pulses (i) follow one or more pulses representing motion in the first direction and (ii) are followed directly by one or more pulses representing motion in the first direction.

Preferably, the method also comprises restraining, from the first counter, a specified number of pulses which represent rotation in the first direction, this restraining step being effected consequent to the occurrence of a predetermined number of pulses which represent rotation in the second direction and (i) are following one or more pulses representing motion in the first direction and (ii) being followed directly by one or more pulses representing motion in the first direction.

Furthermore, the present invention also provides a meter including a rotor member and means providing first pulses indicative of rotation of the rotor member in a first direction and second pulses indicative of rotation of the rotor in a second direction, a first counter storing a cumulative count of the pulses indicating rotation in the first direction, a second counter storing cumulative count of the pulses indicating rotation in the second direction and means for withholding from the second counter a predetermined number of pulses representing rotation in the second direction following and being followed directly by one or more pulses representing motion in the first direction.

Additionally, the present invention provides a method of measuring the consumption of a quantity, the method comprising: applying a meter with a rotor member such that the rotor member is rotated in response to flow of the quantity; providing first pulses indicative of rotation of the rotor member in a first direction and second pulses indicative of rotation of the rotor in a second direction; storing a cumulative count of the pulses indicating rotation in the first direction; storing a cumulative count of the pulses indicating rotation in the second direction; and withholding, from the second counter, a predetermined number of pulses which represent rotation in the second direction following and being followed directly by one or more pulses representing motion in the first direction.

The present invention provides for the reliable and accurate counting of forward and reverse pulses, whether the reverse pulses derive from fraudulent use of the meter or from spurious rotation.

In order that the invention may be clearly understood and readily be carried into effect, it will now be described with reference to the accompanying drawings in which: Figure 1 shows schematically an induction electricity meter embodying the present invention; and Figures 2a, 2b, 2c show the flow chart of operations in another form of induction electricity meter embodying the present invention.

In Fig. 1 the rotor disc of an induction electricity meter is shown at 1, although it could be the rotor of a fluid flow meter. Rotation is determined by counts provided in this example by photocells 2 and 3 receiving light from a light source (not shown) on the remote side of disc 1 via a slot 4 in the disc, the consequent intermittent outputs of the photocells 2, 3 being A, B respectively. The separation of the photocells 2, 3 in a plane parallel to that of disc 1 is substantially less than the width of slot 4, so that at some stage during each rotation of the disc both photocells are producing simultaneously an output signal.

The output signals of photocells 2, 3 are passed to a control unit 5 which forms them into a series of pulses, each corresponding to a revolution of disc 1, the series being divided up according to the direction of rotation of the disc. Thus for forward motion of disc 1, pulses are produced at output E of unit 5 and passed to a "Forward Counter" 6 which gives the current meter (consumption) count. For each reverse revolution of disc 1, a pulse is produced at output F of unit 5 for subsequent processing as described in greater detail below.

In control unit 5 the signals output from photocells 2, 3 are passed to two NAND gates 7 and 8 arranged with an AND gate 9, an "R-S" type flip-flop 10 and a "D-type" flip-flop 11 such that the latter outputs a signal ''1" if unit 5 receives a sequence of signals corresponding to: AeA + BoB. Flip-flop 11 outputs a signal "0" if unit 5 receives a sequence of signals corresponding to: BoA + BoA.

A monostable circuit 1 2 produces a pulse each time it receives a leading edge of a signal corresponding to A + B as output by AND gate 9, the pulse passing to switch 1 3 which is operated by the output of flip-flop 11 in order to direct the pulse to the output E or F as appropriate.

The table for operation of the components within control unit 5 is as indicated below.

NAND - 7 NAND - 8 LIP/FLOP - 10 FLIP/FLOP - 11 IN/OUT IN/OUT S / R t Q D / CK / Q AB AB A 1,0 A 1,0 0 1 0 1 1 0 X A+B 1,1 0 1,1 0 0 0 1 1 1 1 B 0,1 0 0,1 1 0 1 0 1 0 1 B 0,1 0 0,1 1 0 1 0 0 0 X B+B 1,1 0 1,1 0 0 0 0 0 1 0 A -1,0 1 1,0 0 1 0 1 1 0 0 Any pulses directed to output F of unit 5 are passed on to a single pulse store 14; if this store 1 4 receives a sequence of a number of pulses, only the first is stored and the remainder overflow and continue to a reverse counter 1 5 which thereby provides a record of the degree of reverse motion achieved.

The input and output of the store 14 are connected to a NAND gate 16 and an AND gate 1, and the outputs of these gates are passed to an R-S flip flop device 1 8. Thus it is noted when a single reverse pulse is received, and consequently there is produced and output signal of "1" which is passed to a switch 1 9 in order to activate it into a second mode whereby a single pulse store 20 is connected in between output E of unit 5 and forward counter 6. Thus, when forward rotation of disc 1 resumes, the sequence of pulses output from unit 5 must pass to counter 6 via store 20; accordingly the first pulse of that sequence is held in store 20 and never reaches counter 6.The following pulses in the sequence overflow from store 20 and pass on to counter 6, and are also used both to activate switch 1 9 back to its normal mode in which it connects directly output E and counter 6 and to register with a counter 21 that a single reverse pulse had occurred. Once the pulses from unit 5 pass along this direct path, they are used to reset store 14 and store 20.

It is expected that the reverse count will indicate fraud and this counter 1 5 should be in a secure position in the meter accessible only to a special reading attachment. Flip flop 1 8 adds to the counter 15, on the occurrence of an overflow, the single count lost in store 14.

It will be appreciated that the meter will also include, visible to the user, the conventional mechanical register which can be decremented by fraudulent reverse rotation. However counter 6 will show the correct forward count and the difference between these two should correspond to the count held in counter 1 5.

Other means may be provided to vary the proportion of the output pulses counted by counters 6 and 15, for example to implement a change of tariff.

In one modification, the store 20 is also used when there is more than one reverse pulse, i.e.

during fraudulent reversal of the meter. This may be achieved by suitably connecting the line between output F and store 1 4 to switch 1 9 whereby the first of any sequence of pulses passing to store 1 4 will activate switch 1 9 such as to switch in store 20; clearly changes would have to be made to components 16, 1 7 and 18 and counter 21 would need re-location.

In another modification, the meter is capable of detecting when the direction of disc rotation changes in the middle of a normal sequence of photocell-signal transition; such a change may alter a normal sequence of, for example, A A + B B to AeA + BoA < A + BoB. When this type of inopportunely-timed change occurs, the meter makes appropriate adjustment to the signals passing to the counters in order to ensure that the correct amount of counts (in this instance, a single forward count) are recorded. Clearly the risk of this inopportuntely-timed change occuring can be minimised by ensuring that photocells 23 are as close together as feasible in a plane parallel to that of the disc 1.

In another modification, the arrangement for producing signals to be input to control unit 5 is altered such as to obviate the necessity of a slot 4 in disc 1. Thus the light source and the photocells are all positioned on one side of the disc and all are directed to the same reflective side of disc 1. This side has a single black patch positioned such that each photocell produces a signal of decreased output for a short period of each revolution of disc 1, there being some overlap in the decreased-output signals from the two photocells. Thus, in this modification, the signals A and B input to control unit 5 correspond to a decrease in photocell output, not an increase as before.

A meter as described generally above can be modified such that at least some of the functions are achieved by an electronic control unit incorporating one or more microprocessor devices.

The flow charts illustrated in Figs. 2a, 2b and 2c illustrate the operations performed in a microprocessor control unit within another form of meter embodying the present invention. In this meter the disc has no slot and the photocells monitor the passage of a black patch as indicated in the modification described above; thus the signals A and B correspond to a decrease in photocell output.

The output signal from each photocell passes to a separate time-slugged Schmitt-trigger (which sharpens up the waveform and produces a positive pulse corresponding to A or B as appropriate) and then proceeds to a separate terminal (namely C for any signals A from photocell 2, and D for any signals B from photocell 3) of a microcomputer which effects the control operations and storage for the meter. The microprocessor control unit has the following functions and capabilities: an 8-bit byte of RAM storage (hereafter called the P store) which can hold relevant data during the processing operation; an 8-bit byte of RAM storage (hereafter called the R store) which can act as a single pulse store; three counters each with associated storage, one each for recording the number of forward pulses, of single reverse pulses and of multiple reverse pulses.

The P store includes one bit (hereafter called Cp) which is reserved for storing a state of the terminal C, one bit (hereafter called Dp) reserved for storing a state of the terminal D, one bit (hereafter called FWDp) reserved for a representation state of forward motion, and one bit (hereafter called REVp) reserved for a representation state of reverse motion.

The R store is an 8-bit byte which has two possible states, one being X and the other FF.

The microprocessor control unit processes the outputs from the photocells by polling them about 500 times a second and testing them in each poll in the manner shown in the flow charts of Figs. 2a, b and c. In these charts, C and D represent the instantaneous state at terminals C and D upon polling.

Consider now the test procedure. If the test is done when the disc is in a position with the black patch remote from the photocells, then the decision block 30 will effect the routine 1, which keys into P store a specific set of values for Cp, Dp, FWDp and REVp; thereafter the routine ends that test procedure by returning to "poll terminals". If in due course a poll is done when signal A occurs, then the test proceeds to decision 31 which effects routine 2 resulting in modified keying-in to P store. In due course, when a poll is done when there is the signal A + B, the test proceeds through decision block 32 and on to decision block 33 whose function is to determine whether the test relates to a transition from a single photocell decrease (i.e. A or B) to a double photocell decrease (i.e. A + B).Any test which satisfies this criterion passes to decison block 34 which distinguishes between a reverse transition (i.e. B A + B) and a forward transition (i.e. AHA + B), the latter passing to decision block 35. If the forward transition is the first after one or more reverse pulses (i.e. R will be in the FF state), then it is used to reset R in action block 36, there being no incrementation of the forward counter; however any other forward transition passes to action block 37 which causes the forward counter to be incremented by one count.

Decision block 38 passes all correct reverse transitions to decison block 39, but ensures that any test with corrupted values in P store are aborted and a new test is commenced after appropriate resetting by action block 40. Decision block 39 determines whether R store is in a state indicating that there has been immediately previously a test indicating a reverse transition, and if so the test proceeds to action whereby a reverse pulse (to indicate fraudulent use) is registered by action block 41. If there has not been a reverse pulse immediately previously (i.e.

the R store is X, then action block 42 sets R store to its state indicating that it has received a single reverse pulse, and there is no increment in the reverse counter. If the next tested transition is a forward pulse, then the meter may record that the transition recorded at the R store related to a single reverse pulse resulting from a spurious cause; accordingly, the meter may maintain a count of all the single-reverse pulses which occur.

In this form of meter, the R store is used to ensure that both the forward counter and the multiple-reverse counter provide accurate recording of the counts when spurious reverse pulses occur.

Adaptation of the invention to other meters, such as fluid flow meters, will be apparent to those skilled in the art.

Claims

1. A meter including: a rotor member; means for providing first pulses indicative of rotation of the rotor member in a first direction and second pulses indicative of rotation of the rotor in a second direction; a first counter for storing a cumulative count of the pulses indicating rotation in the first direction; a second counter for storing cumulative count of the pulses indicating rotation in the second direction; means for monitoring for a predetermined number of pulses which represent rotation in the second direction, such pulses (i) following one or more pulses representing motion in the first direction and (ii) being followed directly by one or more pulses representing motion in the first direction; and means for inhibiting the passage of a predetermined number of pulses to a counter, the inhibiting means being operable in response to the monitoring means.

2. A meter according to Claim 1, wherein the inhibiting means comprises means for withholding, from the second counter, a predetermined number of pulses which represent rotation in the second direction, such pulses (i) following one or more pulses representing motion in the first direction and (ii) being followed directly by one or more pulses representing motion in the first direction.

3. A meter according to Claim 1 or Claim 2, wherein the inhibiting means comprises means for restraining, from the first counter, a specified number of pulses which represent rotation in the first direction, the restraining means being actuable in response to occurrence of a predetermined number of pulses which represent rotation in the second direction, such predetermined number of pulses following one or more pulses representing motion in the first direction and (ii) being followed directly by one or more pulses representing motion in the first direction.

4. A meter according to Claims 2 and 3, wherein the specified number relating to the restraining means corresponds to the predetermined number relating to the withholding means.

5. A meter according to Claim 3 or Claim 4, wherein the restraining means is actuable by operation of the withholding means.

6. A meter according to any one of Claims 3, 4 or 5, wherein the inhibiting means incorporates a store to comprise both the withholding means and the restraining means.

7. A meter according to any one of the preceding Claims, comprising means to determine the direction of rotation of the rotor member and means to pass pulses, derived from rotation of the rotor member, towards the first counter or the second counter in accordance with the output from the direction-determining means.

8. A meter including a rotor member and means providing first pulses indicative of rotation of the rotor member in a first direction and second pulses indicative of rotation of the rotor in a second direction, a first counter storing a cumulative count of the pulses indicating rotation in the first direction, a second counter storing cumulative count of the pulses indicating rotation in the second direction and means for withholding from the second counter a predetermined number of pulses representing rotation in the second direction following and being followed directly by one or more pulses representing motion in the first direction.

9. A meter substantially as hereinbefore described with reference to and as illustrated in Fig.

1, or in Figs. 2a, 2b and 2c, of the accompanying drawings.

10. A method of measuring the consumption of a quantity, the method comprising: applying a meter with a rotor member such that the rotor member is rotated in response to flow of the quantity; providing first pulses indicative of rotation of the rotor member in a first direction and second pulses indicative of rotation of the rotor in a second direction; storing a cumulative count of the pulses indicating rotation in the first direction; storing a cumulative count of the pulses indicating rotation in the second direction; monitoring for a predetermined number of pulses which represent rotation in the second direction whereby these pulses (i) follow one or more pulses representing motion in the first direction and (ii) are followed directly by one or more pulses representing motion in the first direction; and, when a predetermined number of pulses are detected, inhibiting the passage of a predetermined number of pulses to at least one counter.

11. A method according to Claim 10, comprising withholding, from the second counter, a predetermined number of pulses which represent rotation in the second direction, whereby these pulses (i) follow one or more pulses representing motion in the first direction and (ii) are followed directly by one or more pulses representing motion in the first direction.

12. A method according to Claim 10 or Claim 11, comprising restraining, from the first counter, a specified number of pulses which represent rotation in the first direction, this restraining step being effected consequent to the occurrence of a predetermined number of pulses which represent rotation in the second direction (i) following one or more pulses representing motion in the first direction and (ii) being followed directly by one or more pulses representing motion in the first direction.

1 3. A method of measuring the consumption of a quantity, the method comprising: applying a meter with a rotor member such that the rotor member is rotated in response to flow of the quantity; providing first pulses indicative of rotation of the rotor member in a first direction and second pulses indicative of rotation of the rotor in a second direction; storing a cumulative count of the pulses indicating rotation in the first direction; storing a cumulative count of the pulses indicating rotation in the second direction; and withholding, from the second counter, a predetermined number of pulses which represent rotation in the second direction following and being followed directly by one or more pulses representing motion in the first direction.

14. A method of measuring the consumption of a quantity, the method being substantially as hereinbefore described with reference to and as illustrated in Fig. 1, or in Figs. 2a, 2b and 2c, of the accompanying drawings.