Claims:We claim:
1. A measuring apparatus 400 comprising a measurement sensor 100 and a computational device 300, each having respective commensurate electric powering means 250 and 350, the measurement apparatus 400 having an electrical connection for power and control as well as data communication with the computation device 300, characterized in that
the measurement sensor 100 comprises a measurement means 110, a protected read-write-erase memory 130 having a plurality of calibration tabulation including a plurality of primary calibration tabulation 150 and a plurality of secondary calibration tabulation 170 and a plurality of degenerative calibration tabulation 210 along with an application address 230; and
the computation device 300 comprises a data receiver 310, a correction calculator 370, an input output unit 390 including a configurator 305;
wherein,
the calibration tabulation 150, 170 and 210 is pre-generated in a controlled condition and independent of the computational device 300 with which the measurement means 110 is subsequently to be paired;
the measurement means 110 includes one or more primary measurement means and one or more secondary measurement means;
the primary calibration tabulation 150 is a set of discrete data giving a real value 410 of a primary function and correspondingly a measured value of the primary function of the sensor;
the secondary calibration tabulation 170 is a set of discrete data giving a real value of a support function and correspondingly a measured value of the secondary function of the sensor;
the degenerative calibration tabulation 210 is a set of discrete data giving a value of a degenerative function and correspondingly a predicted value of the primary function of the sensor. The degenerative function is a measure of time and or use of the current measurement sensor which necessitates a re-calibration of the current measurement sensor. The predictive value of the primary function is algorithm, statistical or knowledge based;
the data receiver 310 receives an application address 230 which is a permanent details of the measurement sensor 100, a measurement value 330 and a selected calibration data 340 from the measurement sensor 100;
The configurator 305 is configurable for setting up a names and a measuring units of primary functions, the names and the measuring units of secondary functions, the names and the measuring units of degenerative functions, and for algebraic expression and Boolean expression for data pertaining to each function.
2. The measuring apparatus 400 as claimed in claim 1, wherein the measurement sensor 100 is an electric current measurement sensor.
3. The measuring apparatus 400 as claimed in claim 1, wherein the primary calibration tabulation 150 is a set of discrete real current value 155, a corresponding measured current value 157 and a corresponding measured phase angle error value 159.
4. The measuring apparatus 400 as claimed in claim 1, wherein the secondary calibration tabulation 170 is a set of discrete frequency value 175, a corresponding measured current deviation value 177 and a corresponding measure phase angle error deviation value 179.
5. The measuring apparatus 400 as claimed in claim 1, wherein the secondary calibration tabulation 170 is a set of discrete operational temperature value 195, a corresponding measured current deviation value 197 and a corresponding measure phase angle error deviation value 199.
6. The measuring apparatus 400 as claimed in claim 1, wherein the primary measurement means is a primary and a secondary winding wound on a ferromagnetic core, while the secondary means is any or all of a frequency measurement, a temperature measurement, a humidity measurement, a vibration measurement.
7. The measuring apparatus 400 as claimed in claim 1, wherein the degenerative calibration tabulation 210 is a set of time period 215 in months or years as per industry guidelines, and a corresponding predicted current deviation value 217 and a corresponding predicted phase angle error deviation value 219.
8. The measuring apparatus 400 as claimed in claim 1, wherein the application address 230 of the measurement sensor 100 is a set of level one and level two permanent details of the measurement sensor 100.
9. The measuring apparatus 400 as claimed in claim 1, wherein the electrical connection is a hard wired or a radio connection or a combination thereof.
10. A method of measuring a corrected value of one or more primary function by a measuring apparatus 400 comprising a measurement sensor 100 and a computation device 300, the method comprising the steps of:
i. Pairing the computation device 300 with the measurement sensor 100 by configuring an application address 230 and one or more primary functions, and one or more secondary functions and one or more degenerative function
ii. Seeking and receiving by the computation device 300 a measured value YMP 502 of the primary function
iii. Seeking and receiving by the computation device 300 a next lower real value and corresponding virtual value (XLP, YLS) 510, and a next higher real value and corresponding higher virtual value (XHP, YHP) 520 from the primary calibration tabulation 150.
iv. Computing by the computation device 300 a linear or a non-linear contour of a calibration segment 550
v. Computing by the computation device 300 a real value XMP 501.
vi. Seeking and receiving by the computational device 300 a measured value YMS 504 of a secondary function.
vii. Seeking and receiving by the computational device 300 a next lower real value and corresponding virtual value (XLS, YLS) 511, and a next higher real value and corresponding higher virtual value (XHS, YHS) 521 from the secondary calibration tabulation 170.
viii. Computing by the computational device 300 a linear or a non-linear contour of a calibration segment 551.
ix. Computing by the computation device 300 a real value XMS 503.
x. Determining by the computation device 300 a degenerative function with reference to a real time ageing.
xi. Selecting by the computing device 300 a predicted deviation value of the primary function.
xii. Computing by the computation device 300 a corrected value of the primary function by taking into computation all the real values of the primary function the secondary function and the degenerative function.
11. The method as claimed in claim 10, wherein the computation device 300 considers a default value on seeking and not receiving a virtual value 420.
12. The method as claimed in claim 10, wherein the measurement sensor 100 is any measurement sensor 100 with a compatible application address 230. , Description:Form 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules 2002

Complete Specification
(See section 10 and rule 13)

Title of the Invention:

A MEASUREMENT APPARATUS AND A METHOD FOR
CORRECTING MEASURES THEREFROM

Applicant: SELEC CONTROLS PRIVATE LIMITED
Nationality: Indian
Address: EL27/1, Electronic Zone,
TTC Industrial Area,
MIDC, Mahape,
Navi Mumbai – 400710.
Maharashtra, INDIA.

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION

The present invention relates to measurement, particularly the measurement of analog parameters, and more particularly to a measurement apparatus and method therefor.

BACKGROUND OF THE INVENTION

Present invention is being disclosed with the art and science of current measurement; however it is applicable equally effectively to apparatus and method of measurement of speed of a car or quantity of mayonnaise sauce in a sandwich, and every other effect based measurement.
Measurement of parameters is a known important step in any activity sensitive to quality of output. Use of an effectbased transducer is known for safe and effective measurement. Example – We measure temperature by measuring expansion of mercury or any other suitable liquid.
Such measurement has essentially a measuring sensor and an output device imparting measurement value.
Every effect based measuring sensor has errors in sensing the parameter. The error may be due to the sensor construction, and or due to environment and or due to aging. The same is also true for the output device.
It is also known that such error is different for same design and manufacturing process of measuring sensor as well as output device, primarily due to manufacturing variations. Illustratively, a conventional current transformer which senses primary current by its magnetic effect and then reproduces a secondary current has some error introduced at each stage including but not limited to wire manufacture, winding of wire, placement of wire on a core, generation of magnetic field and then secondary current, and so on.
It is known that an error data, which is essentially a tabulation of factor of error at discrete values of measurement and which is also known as a calibration chart, is generatable, to know the error introduced due to any reason.
When measuring sensor and measuring devices are connected to each other to form a measuring apparatus or measuring system, in which any measuring sensor is connected to any measuring device, the cumulative or system error is Sensor device error + measuring device error. In such cases, the measurement inaccuracies of the sensor are not possible to compensate. So if higher accuracy is required, the individual accuracies of the sensor as well as the measuring device each have to be high. Calibrating the sensor independently and pairing it at the time of connection to the measuring device allows the sensor inaccuracy to be eliminated. This could have been achieved in the normal course only if a specific unit of sensor and a specific unit of measuring device are considered together as a pair or if the two were integrated as a measuring system and calibrated for the final measurement with error elimination techniques. This concept significantly limits industrial flexibility and inflates cost.
Present invention effectively addresses this industrial need and gap.

OBJECTIVES

The objective is to invent an instrument that gives an accurate measurement of a desired parameter.
Another objective is to invent an instrument that gives an accurate measurement over a wide range of desired parameter.
Yet another objective is to invent an instrument that is usable for measurement of different parameters.
Yet another objective is to invent an instrument that effectively utilizes calibration information of the measurement sensor deployed.
Yet another objective is to invent an instrument whose constituents are calibrated independently.
Yet another objective is to invent an instrument whose sensor is changeable and the instrument does not need cumulative calibration.

SUMMARY OF THE INVENTION

The present invention is a measuring apparatus comprising a measurement sensor and a computational device . The measurement sensor comprises a measurement means , a protected read-write-erase memory having a plurality of calibration tabulation including a plurality of primary calibration tabulation and or a plurality of secondary calibration tabulation and or a plurality of degenerative calibration tabulation along with an application address , and a commensurate electric powering means .
A calibration tabulation is a set of discrete data giving a real value of a function and correspondingly a virtual value of the function of the sensor. The virtual value includes a measured value, a predicted value and or a projected value. The calibration tabulation is generated for each and every individual measurement means in a controlled condition and independent of the computational device with the measurement means which is subsequently to be paired. A primary calibration tabulation is a set of discrete data giving a real value of a primary function and correspondingly a measured value of the primary function of the sensor. A secondary calibration tabulation is a set of discrete data giving a real value of a support function and correspondingly a measured value of the secondary function of the sensor.
A measurement means includes one or more primary measurement means and one or more secondary measurement means. A degenerative calibration tabulation is a set of discrete data giving a value of a degenerative function and correspondingly a predicted value of the primary function of the sensor. The predictive value of the primary function is algorithm, statistical or knowledge based. The application address of the measurement sensor is a set of level one and level two permanent details of the measurement sensor . For the current measurement sensor, the level one permanent detail is a current measurement transformation ratio like 200/5 which means a current transformer of 200 Amp primary rating and 5 Amp secondary rating, a permissible temperature value. The level two permanent details is a serial number identifying a source and period of production. The computation device comprises, a data receiver , a correction calculator , an input output unit including a configurator , and a commensurate electric powering means. The data receiver receives an application address, a measurement value and a selected calibration data from the measurement sensor.
The configurator is configured by the user for setting up names and measuring units of primary functions, names and measuring units of secondary functions, names and measuring units of degenerative functions. The configurator is also configured by user for algebraic expression or Boolean expression for data pertaining to each function. Persons skilled in the art are well aware of such behavior of different samples of same measurement sensors, and which is unavoidable due to manufacturing variations from sample to sample. The present invention corrects this anomaly effectively, by pairing any measurement sensor with any computation device . The measurement apparatus has the measurement sensor electrically connected for power and or control as well as data communication with the computation device wherein the functions are configured. The electrical connection is a hard wired or a radio connection or a combination thereof. Techniques for such connection are well known and changing rapidly and are not elaborated here to ensure clarity on inventive details. When the measurement apparatus is activated, the computation device seeks and receives the application address from the measurement sensor . In the illustrative case where the measurement sensor is a current measurement sensor, the computational device receives at least a transformation ratio. The computation device seeks and receives a measured value YMP of a primary function. This measured value YMP is a virtual value. The computation device next seeks a next lower real value and corresponding virtual value (XLP, YLS) , and a next higher real value and corresponding higher virtual value (XHP, YHP) from the primary calibration tabulation . From these two values and the computation device calculates a linear or a non-linear contour of a calibration segment and computes a real value XMP . Illustratively, the linear contour is calculated by deploying a known mathematical expression like Y=mX+c where m is a slope of the contour and c is a constant and these could be easily calculated by solving two algebraic equations. The non-linear contour is likewise calculated by using two or more values from the graph. Selection of which expression to be used is based on application of the measurement apparatus as per present invention.
Likewise, the computational device seeks and receives a measured value YMS of a secondary function. This measured value YMS is a virtual value. The computational device next seeks a next lower real value and corresponding virtual value (XLS, YLS) , and a next higher real value and corresponding higher virtual value (XHS, YHS) from the secondary calibration tabulation . From these two points, the computational device calculates a linear or a non-linear contour of a calibration segment and computes a real value XMS .
Next the computation device determines a degenerative function with reference to a real time ageing and computes a predicted value of the primary function. The computation device computes a corrected value of the primary function by taking into computation all the real values of the primary function the secondary function and the degenerative function.

As a variation, when a measurement sensor connected to a computation device returns no data, the computation device considers a default value, generally a numeric ONE. In other words, a measurement sensor which is merely a conventional sensor with no memory is usable with computation device as well.

BRIEF DESCRIPTION OF DRAWINGS

Figure-1 is a block diagram of an apparatus as per present invention.
Figure-2 is a block diagram of a measurement sensor as per present invention. Figure-3A to 3D are illustrative calibration tables of different measurement parameters.
Figure-4 is a block diagram of a computation device as per present invention.
Figure-5A is a graphical representation of different calibration curves, while Figure 5B, 5C is a graphical representation of a set of calibration points used for measurement correction.
Figure-6A, 6B and 6C is a graphical representation of an illustrative set of real and virtual values for arriving at a corrected measure.

DETAILED DESCRIPTION OF DRAWINGS

Present invention is described with the help of accompanying drawings. The invention has a wide application, and the explanation and illustrations should not be construed to limit the invention.
Figure 1, the present invention is a measuring apparatus 400 comprising a measurement sensor 100 and a computational device 300.
To facilitate easy and unambiguous understanding of the invention, the drawings and description illustrated for an electric current measurement sensor and an electric current computational device .
Figure 2, the measurement sensor 100 comprises a measurement means 110, a protected read-write-erase memory 130 having a plurality of calibration tabulation including a plurality of primary calibration tabulation 150 and or a plurality of secondary calibration tabulation 170 and or a plurality of degenerative calibration tabulation 210 along with an application address 230, and a commensurate electric powering means 250.
A calibration tabulation is a set of discrete data giving a real value 410 of a function and correspondingly a virtual value 420 of the function of the sensor. The virtual value 420 includes a measured value, a predicted value and or a projected value. The calibration tabulation 150, 170 and 210 is pre-generated for each and every individual measurement means in a controlled condition and independent of the computational device 300 with which the measurement means 110 is subsequently to be paired. Illustratively, for an ac current measurement sensor, a tabulation of ratio error is generated by passing a known value of ac current from primary winding of current transformer and capturing the value of ac current as reported by the secondary winding of the current transformer. Here, the known value corresponds to the real value of the function and the reported value corresponds to the virtual value of the function.
A primary calibration tabulation 150 is a set of discrete data giving a real value 410 of a primary function and correspondingly a measured value of the primary function of the sensor.
Correspondingly, an ac current measurement sensor is a conventional current transformer with a primary winding and a secondary winding. Many a time, the primary winding is merely a single conductor passing through a window of a ferromagnetic core. Such a single conductor constitutes ONE turn of the primary winding while a relatively large number of turns are provided on the ferromagnetic core. A dc current measurement sensor may comprise a Hall Sensor.
For a current measurement sensor, the primary calibration tabulation 150 is generally a set of discrete real current value 155, a corresponding measured current value 157 and a corresponding measured phase angle error value 159, Figure 3A.
A secondary calibration tabulation 170 is a set of discrete data giving a real value of a support function and correspondingly a measured value of the secondary function of the sensor.
For the current measurement sensor, the secondary calibration tabulation 170 is generally a set of discrete frequency value 175, a corresponding measured current deviation value 177 and a corresponding measure phase angle error deviation value 179, Figure 3B.
Also, for the current measurement sensor, the secondary calibration tabulation 170 is generally a set of discrete operational temperature value 195, a corresponding measured current deviation value 197 and a corresponding measure phase angle error deviation value 199, Figure 3C.
Consequently, a measurement means 110 includes one or more primary measurement means and one or more secondary measurement means. For a current measurement apparatus, the primary measurement means is a primary and a secondary winding wound on a ferromagnetic core, while the secondary means is but not limited to a frequency measurement, a temperature measurement, a humidity measurement, a vibration measurement.
A degenerative calibration tabulation 210 is a set of discrete data giving a value of a degenerative function and correspondingly a predicted value of the primary function of the sensor. The degenerative function is a measure of time and or use of the current measurement sensor which necessitates a re-calibration of the current measurement sensor. Figure 3D. The predictive value of the primary function is algorithm, statistical or knowledge based.
For the current measurement sensor, the degenerative calibration tabulation 210 is a set of time period 215 in months or years as per industry guidelines, and a corresponding predicted current deviation value 217 and a corresponding predicted phase angle error deviation value 219, Figure 3D.

The application address 230 of the measurement sensor 100 is a set of level one and level two permanent details of the measurement sensor 100. For the current measurement sensor 100, the level one permanent detail is a current measurement transformation ratio like 200/5 which means a current transformer of 200 Amp primary rating and 5 Amp secondary rating, a permissible temperature value. The level two permanent details is a serial number identifying a source and period of production.
Figure 4, the computation device 300 comprises, a data receiver 310, a correction calculator 370, an input output unit 390 including a configurator 305, and a commensurate electric powering means 350.
The data receiver 310 receives an application address 230 , a measurement value 330 and a selected calibration data 340 from the measurement sensor 100.
The configurator 305 is configured by the user for setting up names and measuring units of primary functions, names and measuring units of secondary functions, names and measuring units of degenerative functions.
Example:
Name Measuring Units
Electric current Ampere
Electric voltage Volts
Temperature °Centigrade
Use Month
The configurator 305 is also configured by user for algebraic expression or Boolean expression for data pertaining to each function. Example – data of some function is to be used as a multiplier as it is, while for another function the data may need to be added to or subtracted from a constant, which is generally numeric ONE, or it may be an additive or subtractive function instead of a multiplier.
Figure 5A graphically shows a relation between the real value 410 of a function and correspondingly the virtual values 420 of the function of different measurement sensors. Virtual values are also different for different samples of same type of measurement sensor for same real value. Persons skilled in the art are well aware of such behavior of different samples of same measurement sensors, and which is unavoidable due to manufacturing variations from sample to sample. The present invention corrects this anomaly effectively, by pairing the measurement sensor 100 with the computation device 300.
The measurement apparatus 400 has the measurement sensor 100 electrically connected for power and or control as well as data communication with the computation device 300 wherein the functions are configured. The electrical connection is a hard wired or a radio connection or a combination thereof. Techniques for such connection are well known and changing rapidly and are not elaborated here to ensure clarity on inventive details.
When the measurement apparatus 400 is activated, the computation device 300 seeks and receives the application address 230 from the measurement sensor 100. In the illustrative case where the measurement sensor 100 is a current measurement sensor, the computational device 300 receives at least a transformation ratio.
Figure 5B, the computation device 300 seeks and receives a measured value YMP 502 of a primary function. This measured value YMP 502 is a virtual value. The computation device 300 next seeks a next lower real value and corresponding virtual value (XLP, YLS) 510, and a next higher real value and corresponding higher virtual value (XHP, YHP) 520 from the primary calibration tabulation 150. From these two values 510 and 520, the computation device calculates a linear or a non-linear contour of a calibration segment 550 and computes a real value XMP 501.

Illustratively, the linear contour is calculated by deploying a known mathematical expression like Y=mX+c where m is a slope of the contour and c is a constant and these could be easily calculated by solving two algebraic equations.
The non-linear contour is likewise calculated by using two or more values from the graph. Selection of which expression to be used is based on application of the measurement apparatus as per present invention.
Likewise, Figure 5C, the computational device seeks and receives a measured value YMS 504 of a secondary function. This measured value YMS 504 is a virtual value. The computational device 300 next seeks a next lower real value and corresponding virtual value (XLS, YLS) 511, and a next higher real value and corresponding higher virtual value (XHS, YHS) 521 from the secondary calibration tabulation 170. From these two points, the computational device calculates a linear or a non-linear contour of a calibration segment 551 and computes a real value XMS 503.
Next the computation device 300 determines a degenerative function with reference to a real time ageing and computes a predicted value of the primary function.
The computation device 300 computes a corrected value of the primary function by taking into computation all the real values of the primary function the secondary function and the degenerative function.

Example: For a 4 year old current measurement sensor that measures 66 ampere at a measured frequency of 46 Hz and at a measured temperature of 56°C, a corrected value of the primary function of current computed, in accordance with Figure 6A, 6B, 6C and 3D respectively, would be
= 66.07 x 1.09 x (1+1.13) x (1+0.1) ampere

As a variation, when a measurement sensor 100 connected to a computation device 300 returns no data, the computation device 300 considers a default value, generally a numeric ONE. On other words, a measurement sensor 100 which is merely a conventional sensor with no memory is usable with computation device 300 as well.
The essence of the invention is that the sensor and the device do not need to be calibrated together in factory or at site and thus the measurement sensor 100 and or the computational device 300 with compatible application address 230 are replaceable and or upgradable at a later date. Equally importantly, an economical sensor is usable and the apparatus as per present invention provides a precise output due to inventive method.