The Least uncertainties of measurement for Electrical quantity/measurement as per the ISO GUM:  
1.0  INDICATING AND RECORDING INSTRUMENTS  
MEASUREMENT FUNCTION  WITH LEAST UNCERTAINTIES OF MEASUREMENT  
1.0.1  DC VOLTMETER  Tol(%)  Floor  
0 TO ± 330.00 mV  0.0047  2E06  
0 TO ± 3.3 V  0.0039  4E06  
0 TO ± 33.0 V  0.0039  4E05  
0 TO ± 330.0 V  0.0043  4E04  
0 TO ± 1020 V  0.0043  1E03  
1.0.2  DC CURRENT  Tol(%)  Floor  
0 TO ± 330.00 µA  0.0116  2E08  
0 TO ± 3.3 mA  0.0101  4E08  
0 TO ± 33.0 mA  0.0078  2E07  
0 TO ± 330.0 mA  0.0078  2E06  
0 TO ± 3.0 A  0.0295  3E05  
0 TO ± 10.0 A  0.0465  4E04  
0 TO ± 20.5 A  0.0775  6E04  
1.0.3  RESISTANCE  Tol(%)  Floor  
0 TO 11 Ohm  0.0093  8E04  
11 TO 33 Ohm  0.0093  1E03  
33 TO 110 Ohm  0.0070  1E03  
110 TO 330 Ohm  0.0070  2E03  
330 TO 1.1 kOhm  0.0070  2E03  
1.1 TO 3.3 kOhm  0.0070  2E02  
3.3 TO 11 kOhm  0.0070  2E02  
11 TO 33 kOhm  0.0070  2E01  
33 TO 110 kOhm  0.0085  2E01  
110 TO 330 kOhm  0.0093  2E+00  
330 TO 1.1 MOhm  0.0116  2E+00  
1.1 TO 3.3 MOhm  0.0116  2E+01  
3.3 TO 11 MOhm  0.0465  4E+01  
11TO 33 MOhm  0.0775  2E+03  
33 TO 110 MOhm  0.3876  2E+03  
110 TO 330 MOhm  0.3876  8E+04  
330 TO 1.1 GOhm  1.1628  4E+05  
1.0.4  AC VOLTAGE  FREQUENCY  Tol(%)  Floor  
1.0 to 33 mV  0.01 Hz to 10 Hz  3.876  1E04  
10 Hz to 45 Hz  0.116  2E05  
45 Hz to 10 kHz  0.078  2E05  
10 to 20 kHz  0.116  2E05  
20 to 50 kHz  0.155  2E05  
50 to 100 kHz  0.271  3E05  
100 to 500 kHz  0.775  5E05  
33 to 330 mV  0.01 Hz to 10 Hz  3.876  1E03  
10 Hz to 45 Hz  0.039  2E05  
45 Hz to 10 kHz  0.023  2E05  
10 to 20 kHz  0.054  2E05  
20 to 50 kHz  0.078  3E05  
50 to 100 kHz  0.178  1E04  
100 to 500 kHz  0.388  3E04  
330 to 3.3 V  0.01 Hz to 10 Hz  3.876  1E02  
10 Hz to 45 Hz  0.039  5E05  
45 Hz to 10 kHz  0.023  5E05  
10 to 20 kHz  0.054  5E05  
20 to 50 kHz  0.078  5E05  
50 to 100 kHz  0.178  2E04  
100 to 500 kHz  0.388  7E04  
3.3 to 33.0 V  0.01 Hz to 10 Hz  3.876  1E01  
10 Hz to 45 Hz  0.039  6E04  
45 Hz to 10 kHz  0.023  5E04  
10 to 20 kHz  0.054  5E04  
20 to 50 kHz  0.078  5E04  
50 to 100 kHz  0.178  2E03  
33.0 to 330.0 V  45 Hz to 1 kHz  0.039  2E03  
1 to 10 kHz  0.062  7E03  
10 to 20 kHz  0.070  7E03  
20 to 50 kHz  0.093  7E03  
50 to 100 kHz  0.186  6E02  
330.0 to 1020.0 V  45 Hz to 1 kHz  0.039  2E02  
1 to 5 kHz  0.062  2E02  
5 to 10 kHz  0.070  2E02  
1.0.5  AC CURRENT  FREQUENCY  Tol(%)  Floor  
29 to 330 µA  10 to 20 Hz  0.155  8E08  
20 to 45 Hz  0.116  8E08  
45 Hz to 1 kHz  0.097  8E08  
1 to 5 kHz  0.233  1E07  
5 to 10 kHz  0.620  2E07  
10 to 30 kHz  1.240  3E07  
330 to 3.3 mA  10 to 20 Hz  0.155  1E07  
20 to 45 Hz  0.097  1E07  
45 Hz to 1 kHz  0.078  1E07  
1 to 5 kHz  0.155  2E07  
5 to 10 kHz  0.388  2E07  
10 to 30 kHz  0.775  5E07  
3.3 to 33 mA  10 to 20 Hz  0.140  2E06  
20 to 45 Hz  0.070  2E06  
45 Hz to 1 kHz  0.031  2E06  
1 to 5 kHz  0.062  2E06  
5 to 10 kHz  0.155  2E06  
10 to 30 kHz  0.310  3E06  
33 to 330 mA  10 to 20 Hz  0.140  2E05  
20 to 45 Hz  0.070  2E05  
45 Hz to 1 kHz  0.031  2E05  
1 to 5 kHz  0.078  4E05  
5 to 10 kHz  0.155  8E05  
10 to 30 kHz  0.310  2E04  
330 mA to 1.1 A  10 to 45 Hz  0.140  8E05  
45 Hz to 1 kHz  0.039  8E05  
1 to 5 kHz  0.465  8E04  
5 to 10 kHz  1.938  4E03  
1.1 A to 3.0 A  10 to 45 Hz  0.140  8E05  
45 Hz to 1 kHz  0.047  8E05  
1 to 5 kHz  0.465  8E04  
5 to 10 kHz  1.938  4E03  
3.0 A to 11 A  45 Hz to 100 Hz  0.047  2E03  
100 Hz to 1 kHz  0.078  2E03  
1 to 5 kHz  2.326  2E03  
11 A to 20.5 A  45 Hz to 100 Hz  0.093  4E03  
100 Hz to 1 kHz  0.116  4E03  
1 to 5 kHz  2.326  4E03  
1.0.6  CAPACITANCE  Tol(%)  Floor  
220 pF to 400 pF  0.388  8E12  
0.4 to 1.1 nF  0.388  8E12  
1.1 nF to 3.3 nF  0.388  8E12  
3.3 nF to 11 nF  0.194  8E12  
11 to 33 nF  0.194  8E11  
33 to 110 nF  0.194  8E11  
110 to 330 nF  0.194  2E10  
330 to 1.1 µF  0.194  8E10  
1.1 to 3.3 µF  0.194  2E09  
3.3 to 11 µF  0.194  8E09  
11 to 33 µF  0.310  2E08  
33 to 110 µF  0.349  8E08  
110 to 330 µF  0.349  2E07  
330 µF to 1.1 mF  0.349  8E07  
1.1 to 3.3 mF  0.349  2E06  
3.3 to 11 mF  0.349  8E06  
11 to 33 mF  0.581  2E05  
33 to 110 mF  0.853  8E05  
1.0.7  FREQUENCY  Tol(%)  Floor  
0.01 to 119.99 Hz  0.002  7.8E04  
120 to 1200 Hz  7.8E04  
1.2 to 12 kHz  7.8E04  
12 to 120 kHz  1.2E02  
120 to 1200 kHz  1.2E02  
1.2 to 2 MHz  1.2E02  
1.0.8  DC POWER  % of Watts Output  
33 mV to 1020 V  3.3 to 329.99 mA  0.05  
0.33 to 11 A  0.11  
11 to 20 A  0.2  
1.0.9  AC Power  % of Watts Output  
33 mV to 1020 V  3.3 to 329.99 mA  0.31  
45 Hz to 65 Hz  0.33 to 11 A  0.27  
11 to 20 A  0.27  
1.0.10  Phase Angle  ∆Φ degrees  
33 mV to 1020 V  10 to 65 Hz  0.2  
65 to 500 Hz  0.8  
500 to 1kHz  1.6  
1 kHz to 5 kHz  5  
5 kHz to 10 kHz  9  
1.1  Graphic Recording & Digital storage Recorders  
With least uncertainties as per 1.0  
1.2  Calibrators and Standards  
MEASUREMENT FUNCTION  WITH LEAST UNCERTAINTIES OF MEASUREMENT  
1.2.1  DC VOLTAGE  
0.1 V  ±1.04 µV  
1 V  ±6.00 µV  
10 V  ±50.0 µV  
100 V  ±0.8 mV  
1000 V  ±8.0 mV  
1.2.2  Ohms  
10 Ω  ±0.25 mΩ  
100 Ω  ±2.10 mΩ  
1 kΩ  ±0.015 Ω  
10 kΩ  ±0.15 Ω  
100 kΩ  ±1.5 Ω  
1 MΩ  ±24.0 Ω  
10 MΩ  ±0.74 kΩ  
100 MΩ  ±0.06 MΩ  
1.2.3  DC CURRENT  
100 µA  ±2.0 nA  
1 mA  ±13.0 nA  
10 mA  ±0.13 µA  
100 mA  ±1.8 µA  
1 A  ±0.03 mA  
1.2.4  AC CURRENT  FREQUENCY  
100 µA  1 kHz  ±0.02 µA  
1 mA  1 kHz  ±0.20 µA  
10 mA  1 kHz  ±2.0 µA  
100 mA  1 kHz  ±20.0 µA  
1 A  1 kHz  ±0.30 mA  
1.2.5  AC VOLTAGE  FREQUENCY  
0.01 V  1 kHz  ±5.0 µV  
0.01 V  20 kHz  ±5.0 µV  
0.01 V  100 kHz  ±8.0 µV  
0.01 V  300 kHz  ±16.0 µV  
0.01 V  1 MHz  ±0.03 mV  
0.01 V  4 MHz  ±3.10 mV  
0.1 V  1 kHz  ±0.03 mV  
0.1 V  20 kHz  ±0.03 mV  
0.1 V  100 kHz  ±0.06 mV  
0.1 V  300 kHz  ±0.10 mV  
0.1 V  1 MHz  ±0.3 mV  
0.1 V  4 MHz  ±0.41 mV  
0.1 V  8 MHz  ±0.41 mV  
0.1 V  10 MHz  ±0.47 mV  
1 V  1 kHz  ±0.3 mV  
1 V  20 kHz  ±0.3 mV  
1 V  50 kHz  ±0.3 mV  
1 V  100 kHz  ±0.2 mV  
1 V  300 kHz  ±0.5 mV  
1 V  500 kHz  ±1.1 mV  
1 V  1 MHz  ±1.9 mV  
1 V  4 MHz  ±4.1 mV  
1 V  8 MHz  ±4.1 mV  
1 V  10 MHz  ±4.7 mV  
10 V  10 Hz to 50 kHz  ±3.0 mV  
10 V  100 kHz  ±1.0 mV  
10 V  300 kHz  ±3.0 mV  
10 V  500 kHz  ±11.0 mV  
10 V  1 MHz  ±17.0 mV  
10 V  2 MHz  ±0.127 V  
10 V  4 MHz  ±0.127 V  
10 V  8 MHz  ±0.128 V  
10 V  10 MHz  ±0.46 V  
100 V  1 kHz  ±30.0 mV  
100 V  20 kHz  ±30.0 mV  
100 V  50 kHz  ±30.0 mV  
100 V  100 kHz  ±20.0 mV  
1000 V  1 kHz  ±0.1 V  
1.2.6  FREQUENCY  
1 Hz  ±5 x 106  
10 MHz  ±50 x 108  
1.2.7  CAPACITANCE  
≤ 100 µF  ±0.2%  
> 100 µF  ±1% 
INDEX  CLASS  SUBCLASS  CAPABILITY / UNCERTAINTY  Procedure #’s 
2.1  TEMPERATURE  Radiation pyrometers  calibration of infrared thermometers, with a spectral response range of 6.5 to 18µm, and a preset emissivity of 0.95, with least uncertainty of measurement of – ±1.8°C from 0°C to 300°C 
HKC030 
2.2  TEMPERATURE  Digital temperature indicator systems  with least uncertainties of measurement of – using thermocouple sensor , ±0.23°C from 50°C to 250°C, using metallic resistance sensor, ±0.16°C from 50°C to 250°C, 
HKC063 
2.3  TEMPERATURE  Ancillary temperature measuring instruments – Indicators, recorders and controllers  with least uncertainties of measurement of – for thermocouple temperature indicators, ±0.3°C from 100°C to 1000°C, for metallic resistance thermometer indicators, ±0.06°C from 200°C to 260°C, ±0.1°C from 260°C to 630°C, ±0.2°C from 630°C to 800°C, 
HKC001, HKC001A 
2.4  TEMPERATURE  Dry block calibrators  with least uncertainty of measurement of – ±0.2°C from 50°C to 250°C 
HKC063 
2.5  TEMPERATURE  Calibration of humidity measuring devices  with least uncertainty of measurement of – ±3% RH from 10% to 90% RH 
TBD 
3.1  DIMENSIONAL  Plain plug gauges  with least uncertainties of measurement of – ±0.003mm from 0mm to 25mm, ±0.03mm from 25mm to 300mm, 
HKC012, HKC034, 
3.2  DIMENSIONAL  External micrometers  with least uncertainties of measurement of – ±0.0008mm from 0mm to 25mm, ±0.0012mm from 25mm to 75mm, ±0.0016mm from 75mm to 100mm ±0.006mm from 100mm to 250mm 
HKC007,HKC008 
3.3  DIMENSIONAL  Electronic indicators, dial gauges and test indicators  with least uncertainty of measurement of – ±0.0008mm from 0mm to 25mm 
HKC007,HKC008 
3.4  DIMENSIONAL  Electronic and vernier callipers  with least uncertainties of measurement of – ±0.0008mm from 0mm to 25mm, ±0.0012mm from 25mm to 75mm, ±0.0016mm from 75mm to 100mm ±0.006mm from 100mm to 250mm 
HKC007,HKC008 
3.5  DIMENSIONAL  Feeler gauges  with least uncertainty of measurement of – ±0.003mm from 0mm to 25mm 
HKC034, 
3.6  DIMENSIONAL  Gauge blocks and accessories  with least uncertainties of measurement of – ±0.003mm from 0mm to 25mm, ±0.03mm from 25mm to 300mm, 
HKC012, HKC034, 
3.7  DIMENSIONAL  Length bars and accessories  with least uncertainties of measurement of – ±0.003mm from 0mm to 25mm, ±0.03mm from 25mm to 300mm, 
HKC012, HKC034, 
3.8  DIMENSIONAL  Precision graticules  with least uncertainty of measurement of – ±(3 µm + 3L/1000), L: mm, from 0mm to 150mm 
STANDARD SCALE 
3.9  DIMENSIONAL  Precision linear scales  with least uncertainty of measurement of – for transparent linear scales, ±(3 µm + 3L/1000), L: mm, from 0mm to 150mm 
STANDARD SCALE 
4.1  TORQUE  Torque wrenches  with least uncertainties of measurement of – ±0.5% from 0N·m to 2N·m, ±0.4% from 2N·m to 40N·m, ±0.2% from 40N·m to 400N·m, ±0.2% from 400N·m to 1500N·m, 
HKC035, HKC035A, HKC037, HKC077, HKC077A 
5.1  PRESSURE  Pressure gauges  with least uncertainties of measurement of – ±0.02 kPa from 0 kPa to 200 kPa ±1.2 kPa from 200 kPa to 10000 kPa, ±5 kPa from 10000 kPa to 60000 kPa, ±120 kPa from 60000 kPa to 100000 kPa 
HKC038, HKC039, HKC039A, HKC100 
5.2  PRESSURE  Vacuum gauges  with least uncertainty of measurement of – ±0.02 kPa from 0 kPa abs. to 110 kPa abs. 
HKC038, HKC068, 
5.3  PRESSURE  Pressure transducers  with least uncertainties of measurement of – ±0.02 kPa from 0 kPa to 200 kPa ±1.2 kPa from 200 kPa to 10000 kPa, ±5 kPa from 10000 kPa to 60000 kPa, ±120 kPa from 60000 kPa to 100000 kPa 
HKC038, HKC039, HKC039A, HKC100 
6.1  FLOW  Gas meters  with least uncertainties of measurement of – Air ±1.6% of F.S. from 0 Std mL/min to 300 Std mL/min, ±1.6% of F.S. from 0 Std L/min to 30 Std L/min, ±2.1% of reading or 0.05 Std L/min, whichever is greater, from 0 Std L/min to 300 Std L/min 

6.2  FLOW  Liquid meters  with least uncertainty of measurement of – Water, total volume of, ±1 L from 0 L to 400 L 
HKC036 
7.1  ACOUSTIC  Sound level meters  with least uncertainty of measurement of – ±0.12 dB at 94 dB & 114 dB 
HKC016 
8.1  FREQUENCY AND TIME  Tachometers  with least uncertainty of measurement of – (±0.001% ± 1 digit) from 0 RPM to 60000 RPM 
HKC015 
9.1  MASS  mass standards  with least uncertainty of measurement of – ±0.2 mg from 5 mg to 220 g 
HKC009 
9.2  MASS  Precision laboratory balances  with least uncertainty of measurement of – ±0.1 mg from 5 mg to 220 g 
HKC009 
9.3  MASS  Industrial balances  with least uncertainty of measurement of – ±3 g up to 70 kg 
HKC010 
10.1  FORCE  Load cells  with least uncertainties of measurement of – ±10 N from 0 to 50 kN, ±25 N up to 500 kN, 
HKC055, HKC060 
Definitions and metrology concepts taken into account when we perform our measurements:
1: Measurement
– process of experimentally obtaining one or more quantity values that can reasonably be attributed to a quantity
2: Metrology
– science of measurement and its application
3: Measurand
– quantity intended to be measured
4: Measurement principle
– principle of measurement
– phenomenon serving as a basis of a measurement
5: Measurement method
– method of measurement
6: Measurement procedure
– detailed description of a measurement according to one or more measurement principles and to a given measurement method, based on a measurement model and including any calculation to obtain a measurement result
7: Reference measurement procedure
– measurement procedure accepted as providing measurement results fit for their intended use in assessing measurement trueness of measured quantity values obtained from other measurement procedures for quantities of the same kind, in calibration, or in characterizing reference materials
8: Primary reference measurement
– procedure
– primary reference procedure
– reference measurement procedure used to obtain a measurement result without relation to a measurement standard for a quantity of the same kind
9: Measurement result result of measurement
– set of quantity values being attributed to a measurand together with any other available relevant information
10: Measured quantity value
– value of a measured quantity
– measured value
– quantity value representing a measurement result
11: True quantity value
– true value of a quantity
– true value
– quantity value consistent with the definition of a quantity
12: Conventional quantity value
– conventional value of a quantity
– conventional value
– quantity value attributed by agreement to a quantity for a given purpose
13: Measurement accuracy
– accuracy of measurement
– accuracy
– closeness of agreement between a measured quantity value and a true quantity value of a measurand
14: Measurement trueness
– trueness of measurement
– trueness
– closeness of agreement between the average of an infinite number of replicate measured quantity values and a reference quantity value
15: Measurement precision
– precision
– closeness of agreement between indications or measured quantity values obtained by replicate measurements on the same or similar objects under specified conditions
16: Measurement error
– error of measurement
– error
– measured quantity value minus a reference quantity value
17: Systematic measurement error
– systematic error of measurement
– systematic error
– component of measurement error that in replicate measurements remains constant or varies in a predictable manner
18: Measurement bias
– bias
– estimate of a systematic measurement error
19: Random measurement error
– random error of measurement
– random error
– component of measurement error that in replicate
– measurements varies in an unpredictable manner
20: Repeatability condition of measurement
– repeatability condition
– condition of measurement, out of a set of conditions that includes the same measurement procedure, same operators, same measuring system, same operating conditions and same location, and replicate measurements on the same or similar objects over a short period of time
21: Measurement repeatability
– repeatability
– measurement precision under a set of repeatability conditions of measurement
22: Intermediate precision condition of
– measurement
– intermediate precision condition
– condition of measurement, out of a set of conditions that includes the same measurement procedure, same location, and replicate measurements on the same or similar objects over an extended period of time, but may include other conditions involving changes
23: Intermediate precision condition of
– measurement
– intermediate precision condition
– condition of measurement, out of a set of conditions that includes the same measurement procedure, same location, and replicate measurements on the same or similar objects over an extended period of time, but may include other conditions involving changes
24: Intermediate precision condition of
– measurement
– intermediate precision condition
– condition of measurement, out of a set of conditions that includes the same measurement procedure, same location, and replicate measurements on the same or similar objects over an extended period of time, but may include other conditions involving changes
25: Reproducibility condition of measurement
– reproducibility condition
– condition of measurement, out of a set of conditions that includes different locations, operators, measuring systems, and replicate measurements on the same or similar objects
26: Measurement reproducibility
– reproducibility
– measurement precision under reproducibility conditions of measurement
27: Measurement uncertainty
– uncertainty of measurement
– uncertainty
– nonnegative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used
28: Definitional uncertainty
– component of measurement uncertainty resulting from the finite amount of detail in the definition of a measurand
29: Type A evaluation of measurement
– uncertainty
– Type A evaluation
– evaluation of a component of measurement uncertainty by a statistical analysis of measured quantity values obtained under defined measurement conditions
30: Type B evaluation of measurement
– uncertainty
– Type B evaluation
– evaluation of a component of measurement uncertainty determined by means other than a Type A evaluation of measurement uncertainty
31: Standard measurement uncertainty
– standard uncertainty of measurement
– standard uncertainty
– measurement uncertainty expressed as a standard deviation
32: Combined standard measurement
– uncertainty
– combined standard uncertainty
– standard measurement uncertainty that is obtained using the individual standard measurement uncertainties associated with the input quantities in a measurement model
33: Relative standard measurement
– uncertainty
– standard measurement uncertainty divided by the absolute value of the measured quantity value
34: Uncertainty budget
– statement of a measurement uncertainty, of the components of that measurement uncertainty, and of their calculation and combination
35: Expanded measurement uncertainty
– expanded uncertainty
– product of a combined standard measurement uncertainty and a factor larger than the number one
36: Coverage interval
– interval containing the set of true quantity values of a measurand with a stated probability, based on the information available
37: coverage probability
– probability that the set of true quantity values of a measurand is contained within a specified coverage interval
38: coverage factor
– number larger than one by which a combined standard measurement uncertainty is multiplied to obtain an expanded measurement uncertainty
39: Calibration
– operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication
40: Calibration hierarchy
– sequence of calibrations from a reference to the final measuring system, where the outcome of each calibration depends on the outcome of the previous calibration
41: Metrological traceability
– property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty
42: Traceability
– The abbreviated term “traceability” is sometimes used to mean metrological traceability as well as other concepts, such as ‘sample traceability’ or ‘document traceability’ or ‘instrument traceability’ or ‘material traceability’, where the history (“trace”) of an item is meant. Therefore, the full term of “metrological traceability” is preferred if there is any risk of confusion.
43: The ILAC considers the elements for confirming metrological traceability to be an unbroken metrological traceability chain to an international measurement standard or a national measurement standard, a documented measurement uncertainty, a documented measurement procedure, technical competence, metrological traceability to the SI, and calibration intervals
44: Metrological traceability chain
– traceability chain
– sequence of measurement standards and calibrations that is used to relate a measurement result to a reference
45: Metrological traceability to
– a measurement unit
– metrological traceability to a unit
– metrological traceability where the reference is the definition of a measurement unit through its practical realization
46: Verification
– provision of objective evidence that a given item fulfills specified requirements
47: Validation
– verification, where the specified requirements are adequate for an intended use
48: Metrological comparability of
– measurement results
– metrological comparability
– comparability of measurement results, for quantities of a given kind, that are metrologically traceable to the same reference
49: Metrological compatibility of
– measurement results
– metrological compatibility
– property of a set of measurement results for a specified measurand, such that the absolute value of the difference of any pair of measured quantity values from two different measurement results is smaller than some chosen multiple of the standard measurement uncertainty of that difference
50: Measurement model
– model of measurement
– model
– mathematical relation among all quantities known to be involved in a measurement