Abstract:
This invention relates to electrical connectors used with non-invasive toroidal conductivity sensors and calibration thereof. A removable breaking calibration connector is provided for temporary insertion in the electrical circuit to selectively break connection to a sense toroid for zero out calibration in situ while retaining connection to the drive toroid and other peripherals, even when process fluid is flowing in the pipes.

Description:
RELATED APPLICATION DATA  
     The present application claims benefit of 60/548,924 filed on Feb. 27, 2004. 
    
    
     FIELD OF INVENTION 
     The present invention relates generally to toroidal conductivity sensors and more particularly to connectors therefor, including removable breaking calibration connector portions for calibration thereof. 
     BACKGROUND OF INVENTION 
     Toroidal electrodeless conductivity (EC) sensors are used to measure conductivity in a process fluid by use of electromagnetic cores, i.e., toroids. At least two toroids are typically used, one being a ‘drive’ toroid and the other being a ‘sense’ toroid. The sensor unit applies current to the drive toroid, which in turn induces a current in the sense toroid, through a current induced in the process fluid. The current induced in the sense toroid is proportional to the conductivity of the process fluid passing through the process pipe and through the toroids. 
     The toroidal conductivity sensors have been one of the industry standards for a long time. Until recently most of the toroidal sensors were invasive in nature, that is, the sensor protruded into the process flow. This has worked well in the industry for many years in many applications. However, in some applications the invasive nature of such toroidal EC sensors presents an undesirable impediment of the process flow. This impediment may be particularly problematic in applications in which the process flow is relatively thick and/or viscous, which tend to generate buildup around the sensor, which in turn, may lead to erroneous conductivity measurements. 
     Recently, flowthrough-type EC sensors have been developed to overcome the abovementioned problems associated with the use of invasive type toroidal conductivity sensors. An example of a sensor of this type is known as the 871FT™ toroidal electrodeless conductivity (EC) sensor available from Invensys Systems, Inc. (Foxboro, Mass.) in which the sensor portion is external to the process flow. 
     However, currently available industrial toroidal EC sensors are typically installed by hand-wiring the sensors either to an analyzer or junction box, e.g., using hand tools. A drawback of this approach is that this installation is relatively labor intensive, and there is a possibility that such hand-wiring may be performed incorrectly. 
     Moreover, in most industrial installations, the cable connecting the sensor to the analyzer or junction box is disposed within electrical conduit to prevent possible degradation of the cable either through weathering or exposure to many of the harsh chemicals used in the process industry. In many instances these sensors are located far away, sometimes at a distance of up to 30 m or more, from the analyzer. In these situations, if the sensor is to be removed for replacement, often some or all of the wiring needs to be removed and then reinstalled, causing undesirable delays and costs associated with process down-time. 
     These toroidal EC sensors also need to calibrated from time to time. For this purpose, toroidal EC sensors such as the aforementioned 871FT™ device, may be provided with calibration ports. These ports enable a user to input a specific known conductivity value to the sensor which may then be detected by the sensor in a conventional manner. However, in order to calibrate the process for low-end conductivity and/or to zero out the sensor, the process pipe typically needs to be drained completely of any process fluid. In an application in which the process pipe extends vertically, draining may be relatively easy to carry out. However, in an application with horizontal mounting, unless the process pipe is pitched, nominally the only way to accomplish the zero reading is to uninstall the unit and then thoroughly dry the inside of the process pipe. This may be relatively difficult and potentially hazardous, e.g., in the event the process fluid is caustic or otherwise aggressive. In either case, such emptying or drying of the process pipe of the process fluid poses a problem to the user because it generally requires that the process be shut-down, thereby increasing the cost of production. 
     Hence there is a need for a method of quickly replacing a sensor inline and for effecting low-end calibration of conductivity sensors without interrupting the production process. 
     SUMMARY 
     One aspect of the present invention includes a toroidal conductivity sensor assembly including a toroidal conductivity sensor having a drive toroid and a sense toroid. The sensor is configured for disposition in-situ within a process flow path. An analyzer is configured to control operation of the sensor, and a multiple conductor cable communicably couples the sensor to the analyzer. A multiple conductor connector releasably couples a sensor end of the cable to the sensor, and includes a male portion and a female portion configured for mutual, releasable engagement. The connector also includes an intermediate calibration portion configured for being interposed between the male and female portions in communicable engagement therewith. The calibration portion blocks electric signals between the analyzer and the sense toroid, and passes electric signals between the analyzer and the drive toroid, and is configured for being temporarily interposed between the male and female portions to effect zero out calibration of the sensor. 
     Another aspect of the invention includes a removable breaking calibration connector portion for effecting zero out calibration in-situ for a toroidal conductivity sensor having a drive toroid and a sense toroid disposed in communication with an analyzer. The breaking calibration connector portion includes first and second interfaces configured for communicable engagement with the analyzer and sensor. Circuit elements are disposed electrically between the first and second interfaces, and are configured to temporarily block electric signals between the analyzer and the sense toroid. The circuit elements as also configured to pass electric signals between the analyzer and the drive toroid. The calibration portion thus permits zero out calibration of the sensor without emptying the sensor of process fluid. 
     A still further aspect of the invention includes a method of calibrating a toroidal connectivity sensor having a drive toroid and a sense toroid. The method includes unmating male and female portions of a multiple conductor connector, and temporarily disposing and mating the previously mentioned calibration connector portion intermediately between the male and female portions, respectively, so that the breaking calibration connector portion restores connection between the analyzer and the drive toroid and other peripheral devices, and breaks connection between the analyzer and the sense toroid. The method further includes carrying out zero out calibration of the toroidal conductivity sensor using the analyzer, removing the breaking calibration connector portion, and mating the male and female portions, so that zero out calibration for the toroidal conductivity sensor is effected. 
     A yet further aspect of the invention includes a connector for communicably coupling an electronic analyzer to a toroidal conductivity sensor having a drive toroid and a sense toroid. The connector includes multiple conductor connector portions disposed to releasably couple a sensor end of a multiple conductor cable to the sensor, the connector portions including a male portion and a female portion configured for mutual, releasable engagement. An intermediate calibration portion is configured for being interposed between the male and female portions in communicable engagement therewith, and is configured to block electric signals between the analyzer and the sense toroid, and to pass electric signals between the analyzer and the drive toroid. The calibration portion is configured for being temporarily interposed between the male and female portions to effect zero out calibration of the sensor. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       A more complete understanding of the invention and a fuller appreciation of the many attendant advantages thereof will be derived by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  is a schematic view of an embodiment of the present invention, with two connector portions in an unmated configuration; 
         FIG. 2  is a schematic view, on an enlarged scale, of the connector portions of  FIG. 1 , in a mated configuration; and 
         FIG. 3  is a schematic, exploded view of a third connector portion disposed between the connector portions of  FIGS. 1 and 2 . 
       
         
           
                 
               
                 
                 
               
             
                 
                     
                 
                 
                   List of parts: 
                 
               
            
             
                 
                   Number 
                   Nomenclature of the part 
                 
                 
                     
                 
                 
                   10 
                   drive toroid 
                 
                 
                   12 
                   sense toroid 
                 
                 
                   14 
                   toroidal conductivity sensor 
                 
                 
                   16 
                   process flow pipe 
                 
                 
                   18 
                   analyzer/transmitter 
                 
                 
                   20 
                   sensor cable 
                 
                 
                   22 
                   sensor end of sensor cable 20 
                 
                 
                   24 
                   analyzer end of sensor cable 20 
                 
                 
                   26 
                   connector 
                 
                 
                   28 
                   male portion of connector 26 
                 
                 
                   30 
                   female portion of connector 26 
                 
                 
                   32 
                   breaking calibration connector 
                 
                 
                   34 
                   male portion of breaking calibration connector 32 
                 
                 
                   36 
                   female portion of breaking calibration connector 32 
                 
                 
                   38 
                   electrical conducting path only for analyzer, drive toroid and 
                 
                 
                     
                   other peripherals 
                 
                 
                   39 
                   insulator 
                 
                 
                   40 
                   calibration port 
                 
                 
                     
                 
               
            
           
         
       
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized. It is also to be understood that structural, procedural and system changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents. For clarity of exposition, like features shown in the accompanying drawings are indicated with like reference numerals and similar features as shown in alternate embodiments in the drawings are indicated with similar reference numerals. 
     Referring to  FIGS. 1 and 2 , a toroidal conductivity sensor  14 , which includes a drive toroid  10  and a sense toroid  12 , is disposed along a process flow pipe  16 . During operation, a process fluid flows through the flow pipe  16  and through a flow path defined by sensor  14 , which extends through the toroids  10 ,  12 . 
     Sensor  14  is connected to an analyzer (which, as used herein, also refers to a transmitter)  18  by a sensor cable  20 , having a sensor end  22  for connecting to the sensor  14  and an analyzer end  24  for connecting to an analyzer/transmitter  18 . Moreover, embodiments of the invention include a multiple contact connector  26  to permit convenient replacement and/or calibration of sensor  14 , as discussed in greater detail hereinbelow. Connector  26  may include nominally any suitable commercially available connector, such as the RO4 series™ miniature circular waterproof connectors available from Tajimi Electronics Co., Ltd (Tokyo, Japan). 
     Connector  26  includes matable portions, shown unmated in  FIG. 1  and mated in  FIG. 2 . For convenience, these portions are respectively described herein as male and female portions  28  and  30 . In the embodiment shown, portion  28  is coupled to sensor  14  either directly or via a portion of cable  20 , as discussed hereinbelow, while portion  30  is coupled to analyzer/transmitter  18  via a majority of cable  20 . The skilled artisan will recognize that the orientation of connector portions  28  and  30  is a matter of choice, and may be reversed, e.g., with portion  28  coupled to analyzer/transmitter  18 , and portion  30  coupled to sensor  14 . 
     Connector  26  may be disposed at nominally any convenient location along cable  20 , though in desired embodiments is disposed at the sensor end of cable  20  (e.g., closer to sensor  14  than to analyzer  18 ). Alternatively, connector  26  may be disposed further upstream (i.e., towards analyzer/transmitter  18 ) on the sensor cable  20 , so that a portion of cable  20  is disposed upstream, and a portion is disposed downstream, of the connector. 
     The connector  26  permits the customer to quickly replace the sensor  14  and/or the analyzer/transmitter  18  in the event of a failure or scheduled maintenance, to advantageously eliminate or reduce down-time and costs associated therewith. 
     Turning now to  FIG. 3 , connector  26  may be provided with a third portion, referred to herein as a breaking calibration connector  32 , configured for being temporarily disposed intermediately between the male portion  28  and the female portion  30  of the connector  26 . In the embodiment shown, a female portion  36  of calibration connector  32  may be mated with the male portion  28  of the connector  26  and a male portion  34  of calibration connector  32  may be mated with the female portion  30  of connector  26 . 
     The breaking calibration connector  32  is constructed so that when installed, it selectively electrically isolates a portion of the sensor  14  from analyzer/transmitter  18 , while connecting other portions thereto. When installed, calibration connector  32  electrically isolates the sense toroid  12  by effectively blocking the electrical conducting path between toroid  12  and analyzer  18 . Connector  32  accomplishes this by inserting an electrical insulator  39  between otherwise matable electrical conductors connector portions  28  and  30  associated with toroid  12 . 
     At the same time, calibration connector  32  effectively inserts electrical conductors  38  ( FIG. 3 ) between other matable contacts of connector portions  28  and  30 . In this manner, while toroid  12  is electrically isolated, the other portions of sensor  14 , including drive toroid  10  and any other peripheral devices such as temperature probes and the like, may operate in a conventional manner. 
     Calibration connector portion  32  thus enables one to carry out a ‘zero out’ and/or low-end calibration of sensor  14  in-situ, that is without removing the sensor  14  from the process fluid pipe or having to empty the pipe  16 . This is accomplished by letting analyzer/transmitter  18  believe it is coupled to a fully functional sensor  14  (by virtue of its connection  38  to drive toroid  10 , etc.,) while detecting the same lack of signal from sense toroid  12  that it would otherwise detect in the event pipe  16  were empty. 
     Once ‘zero out’ calibration is completed, breaking calibration connector  32  may be removed and portions  28  and  30  of connector  26  re-connected to one another, to restore continuity, and thus normal operation, of both toroids  10  and  12 . 
     Additional calibrations, such as full or mid-scale calibration may be completed in a conventional manner, such as by applying a known conductivity value (e.g., a value higher than that provided by the particular fluid currently disposed within conduit  16 ), to calibration port  40  ( FIG. 1 ). Those skilled in the art will recognize that these additional calibrations may be accomplished by coupling a conventional decade box or one or more discrete resistors to calibration port  40 . 
     Although the calibration connector  32  is shown and described as a hardware device, those skilled in the art should recognize that connector  32  may be implemented in software or a combination of hardware and software without departing from the spirit and scope of the present invention. 
     Similarly, although sensor  14  and analyzer  18  have been shown and described as being communicably coupled to one another by hardwire (cable  20 ), it should be understood that such connection may be effected wirelessly, e.g., using conventional Wi-Fi (802.11x) or Bluetooth™ technology, without departing from the spirit and scope of the invention. In this regard, connector  32  may be operationally disposed between the sensor and its wireless connection, or between the analyzer and its wireless connection. Alternatively, connector  32  may be wirelessly interposed between sensor  14  and analyzer  18 , to selectively prevent signals from passing between the analyzer and the sense toroid as described herein. 
     Furthermore, although connector  32  has been shown and described as being physically separable from male and female connector portions  28  and  30  of connector  26 , the skilled artisan should recognize that connector  32  may be disposed integrally with connector  26 , e.g., to either portion  28  or portion  30 , and simply actuated when desired by suitable switch means, without departing from the spirit and scope of the invention. 
     Having described embodiments of the invention, the following is a description of an exemplary method of use thereof. Referring to Table I, a method is provided for calibrating a toroidal connectivity sensor  14 . This method includes unmating  52  male and female portions  28  and  30  of connector  26 , and temporarily mating  54  calibration connector  32  intermediately therebetween, to restore connection between analyzer  18  and drive toroid  10  (and any other devices) and break connection between analyzer  18  and sense toroid  12 . Zero out calibration of the toroidal conductivity sensor  14  is then carried out  56  using analyzer  18 , followed by removal  58  of the connector  32  and re-mating  60  male and female portions  28  and  30 . Optionally, one or more known conductivity values may be applied  62  to a calibration port  40  of sensor  14 , followed by non-zero calibration  64  of sensor  14  using the analyzer. 
     
       
         
               
               
             
           
               
                 TABLE I 
               
               
                   
               
             
             
               
                 52 
                 unmating male and female portions 28 and 30 of connector 26 
               
               
                 54 
                 temporarily disposing and mating calibration connector 32 
               
               
                   
                 intermediately between male and female portions 28 and 30, to 
               
               
                   
                 restore connection between analyzer 18 and drive toroid 10 (and any 
               
               
                   
                 other devices), and breaks connection between analyzer 18 and sense 
               
               
                   
                 toroid 12 
               
               
                 56 
                 carrying out zero out calibration 
               
               
                 58 
                 removing connector 32 
               
               
                 60 
                 re-mating connector 26 
               
               
                 62 
                 optionally applying known conductivity value(s) to a calibration port 
               
               
                   
                 40 
               
               
                 64 
                 carrying out non-zero calibration of the toroidal conductivity sensor 
               
               
                   
                 14 using the analyzer. 
               
               
                   
               
             
          
         
       
     
     While the above description contains many specificities, these should not be construed as limitations in the scope of the invention, but rather as an exemplification of one or more desired embodiments thereof. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their equivalents.