CRITERIA FOR LABORATORY ACCREDITATION IN THE FIELD OF ELECTRICAL LF METROLOGY Approved By: Senior Manager: Mpho Phaloane Revised By: Specialist Technical Committee Date of Approval: 2015-08-26 Date of Implementation: 2015-08-26 SANAS Page 1 of 13
CONTENTS: 1. Purpose and Scope... 3 2. References... 3 3. Definitions... 3 4. Abbreviations... 3 5. Environmental Requirements... 4 6. General Requirements... 4 7. Technical Requirements... 4 8. The Accreditation Schedule... 6 APPENDIX 1: Schedule of Accreditation... 7 ADDENDUM 1: Amendment Record... 13 SANAS Page 2 of 13
1. Purpose and Scope The purpose of this document is to define the specific environmental, general and technical requirements to be met by accredited calibration laboratories in the discipline of LF metrology. This document is applicable to accredited bodies in this discipline and as defined in the Accreditation Act, Act No. 19 of 2006 [3] 2. References [1] OHS Act, 1993 Environmental Regulations 1987 Lighting [2] OHS Act, 1993 General Admin Regulations 1994 Handling of Hazardous Chemical Substances [3] Accreditation Act No. 19 of 2006: Accreditation for Conformity Assessment, Calibration and Good Laboratory Practice Act, 2006 [4] EURAMET cg-15/v0.1 Guidelines on the Calibration of Digital Multimeters [5] EURAMET cg-7 /v1.0 Calibration of Oscilloscopes [6] EURAMET cg-11/v2.0 Guidelines on the Calibration of Temperature Indicators and Simulators by Electrical Simulation and Measurement [7] TG 02-01 Guidance on the calibration of insulation testers [8] ILAC-P14:01/2013 ILAC Policy for Uncertainty in Calibration [9] BIPM-KCDB Classification of services in electricity and magnetism,. 3. Definitions Accredited Body: Accredited body means an organization or facility that has been accredited by SANAS or by a member of the recognition arrangements of the International Laboratory Accreditation Co-operation (ILAC) or the International Accreditation Forum (IAF); [3] Calibration and Measurement Capability (CMC) A CMC is a calibration and measurement capability available to customers under normal conditions: a) as described in the laboratory s scope of accreditation granted by a signatory to the ILAC Arrangement; or b) as published in the BIPM key comparison database (KCDB) of the CIPM MRA. [8] Limitation imposed: Parameter(s) does/do not comply with the specification. The certificate must clearly indicate parameter(s) affected. An appropriate sticker shall be affixed to the instrument. Partial Calibration: Significant parameter(s) were not calibrated or are not traceable. The certificate must clearly indicate parameters affected. An appropriate sticker shall be affixed to the instrument. 4. Abbreviations BIPM CMC LF EA KCBD SANAS International Bureau of Weights and Measures Calibration and Measurement Capability Direct Current Low Frequency European Accreditation Cooperation Key Comparison Data Base South African National Accreditation System SANAS Page 3 of 13
5. Environmental Requirements An accredited laboratory working in the field of LF metrology shall operate under the following environmental conditions: 5.1 The laboratory should be maintained at a temperature of 23 ºC ± 3 ºC. Records of the ambient temperature shall be maintained by the laboratory. 5.2 Where measurements are performed outside of the specified temperature, the laboratory shall produce evidence that the environmental effects have been considered in the evaluation of the uncertainty of measurement. 5.3 The rate of change in the ambient temperature should preferably be less than 1 ºC/hour. 5.4 During the evaluation of environmental conditions note should be taken of possible temperature gradients and care should be taken to ensure that monitoring equipment reflect the conditions in the specific area/s where the calibration work is performed. 5.5 The relative humidity conditions within the laboratory shall be monitored and recorded. It is recommended that relative humidity be maintained between 30 % rh and 60 % rh. At relative humidity levels below the recommended lower limit it may be necessary to take precautions to avoid damage to instrumentation due to static build-up. At levels above the maximum stated limit, the atmosphere shall be non-condensing. 5.6 The quality of the electrical supply to the laboratory needs to be evaluated and monitored where this may have an effect on the accredited capabilities of the laboratory. 5.7 The level of electromagnetic interference should be measured and evaluated, initially and from time to time, to see if it will have any effect on the accredited capabilities of the laboratory. 5.8 A high degree of cleanliness and appropriate lighting shall be maintained in the laboratory. [1][2] 6. General Requirements 6.1 Laboratories operating in the field of LF may be accredited for the basic group of functions to calibrate instruments for voltage, current and resistance. (Additional or alternative functions are addressed in Section 7). 6.2 Unless all the functions and ranges of an instrument have been calibrated and linearity at the base range checked the calibration shall be identified as a Partial Calibration. 7. Technical Requirements 7.1 Multimeters In the absence of the manufacturer s calibration procedures for the calibration of digital multimeters guidelines have been provided in the EURAMET cg-15 publication that has been accepted by the SANAS LF STC as a reference document [4]. 7.2 Oscilloscopes 7.2.1 In the absence of manufacturer s calibration procedures, guidelines on the calibration of oscilloscopes have been provided in the EURAMET cg-7 publication, which has been accepted by the SANAS LF STC as a reference document [5]. SANAS Page 4 of 13
7.2.2 Electrical LF Laboratories accredited for the calibration of Oscilloscopes are limited to a bandwidth 250 MHz 7.2.3 Uncertainty budgets shall be available for the vertical, horizontal and bandwidth functions. 7.2.4 Rise-time may be calculated from bandwidth, up to the frequency of 250 MHz, using the formula 0.35/BW (MHz) [5]. 7.3 Temperature readout devices/simulators 7.3.1 Laboratories must apply separately for the calibration of temperature read-out devices and simulators by means of electrical simulation. 7.3.2 In the instance of thermocouple instrumentation the use of ice baths and/or reference junctions shall be addressed (Reference [6]). 7.3.3 The laboratories shall comply with any additional requirements for electrical simulation as specified in TR19 Criteria for accreditation in the field of Temperature Metrology. 7.3.4 In the case where a Thermometer (without a probe) is submitted for electrical simulation calibration (i.e. not a multifunction instrument such as a DMM), then the calibration of the thermometer shall be regarded as a partial calibration. 7.3.5 Laboratories accredited for the electrical simulation of temperature may be assessed for this parameter separately, typically at least once per assessment cycle, the cost of which shall be borne by the laboratory. 7.4 Frequency calibration of digital multimeters 7.4.1 Many modern digital multimeters include a low-resolution low-accuracy function that allows for frequency measurement. A multi-function calibrator may be used to perform this calibration under the following conditions: Range: 0.1 Hz to 2 MHz, Accuracy: ±25 ppm ±500 µhz 7.4.2 The reported results shall include the applied voltage level in addition to the frequency. 7.5 High voltage measurements 7.5.1 Where the verification of a measure only function is restricted by the ability to source the full range required, the laboratory shall at least provide evidence that ratio verifications were performed at a portion of the range where accredited source facilities were available. 7.6 Insulation testers 7.6.1 In the absence of manufacturer s calibration procedures, laboratories accredited for the calibration of Insulation testers should follow the guidelines as specified in the SANAS document. [7] 7.7 Capacitance 7.7.1 Laboratory standards may be in the form of a set of fixed capacitors, capacitance decade boxes or as an alternative the active capacitance source of a multifunction calibrator may be used. SANAS Page 5 of 13
7.8 Inductance 7.8.1 The requirements for inductance calibrations are similar to that of capacitance with the exception that active sources are not commonly available. 7.9 AC power and energy 7.9.1 Laboratory standards and traceability for Voltage, Current, Phase and Time must be available and maintained in the laboratory, alternatively traceability may be obtained from a wattmeter, or energy reference standard. 7.9.2 In the absence of manufacturer s calibration procedures and accuracy specifications, attention must be given to the accuracy specifications as per National regulatory documents and Regional power and energy instrumentation specifications. 8. The Accreditation Schedule 8.1 The numbering system adopted for the LF accreditation schedule follows the numbering and classification of services in Electricity and Magnetism as adopted by the BIPM for use in the KCDB. [9] 8.2 The accreditation schedule shall follow the format, numbering system and functions detailed in Appendix 1. The measurement conditions, ranges and uncertainties quoted are for illustrative purposes only. 8.3 It should be noted that it is permissible to state either specific values, ranges or a combination of the two. SANAS Page 6 of 13
Appendix 1: Schedule of Accreditation S C H E D U L E O F A C C R E D I T A T I O N LOW FREQUENCY METROLOGY Facility Number: 100 Permanent Address of Laboratory: Super laboratory Building 21, BSAAF Campus Bosveld Road Sandton Technical Signatories : Mr A Accuracte : Mr D Debate Postal Address: Private Bag X 88 Bosveld Ridge 0021 Tel Fax Email ITEM : (011) 621-0123 : (011) 621-4567 : accurate@super.co.za : debate@super.co.za 1 voltage MEASURED QUANTITY OR TYPE OF GAUGE OR INSTRUMENT AND NOMINAL RANGE 1.1 voltage sources 1.1.1 (a) Single values ( 10 V) reference standards 1 V 1,018 V 10 V 1.1.2 Low values ( 10 V) 100 mv 1 V 10 V 1.1.3 Intermediate values (> 10 V to 1100 V) 100 V 1000 V 1.2 voltage meters Nominated Representative Issue No. Date of Issue Expiry Date NOMINAL FREQUENCY 1.2.1 Very low values ( 1 mv) Digital multimeter, nano voltmeters 0 mv 1 mv : Ms O Quality : 01 : 31 May 2017 : 30 May 2022 CALIBRATION AND MEASUREMENT CAPABILITY EXPRESSED AS AN UNCERTAINTY (±) 1 10-7 U 1 10-7 U 2 10-8 U 12 10-6 U 1,6 10-6 U 1,2 10-6 U 1,5 10-6 U 1 10-5 U 10 nv 5 10-5 U 1.2.2 Intermediate values (> 1 mv to 1100 V) Digital multimeters, nano voltmeters 1 mv to 10 mv 5 10-5 U 10 mv to 100 mv 2 10-5 U 0,1 V to 1000 V 1 10-5 U 2 resistance 2.1 resistance standards and sources. 2.1.1 Low values ( 1 Ω) Fixed resistor, resistance box, multifunction calibrator 1 mω to 10 mω 6 10-5 R 10 mω to 1 Ω 6 10-6 R Original date of accreditation: 31 May 2017 Page 1 of 6 SANAS Page 7 of 13
The CMC, expressed as an expanded uncertainty of measurement, is stated as the standard uncertainty of measurement multiplied by a coverage factor k = 2, corresponding to a confidence level of approximately 95% ANNEXURE A Facility Number: 100 Date of Issue: 31 May 2017 Expiry Date: 30 May 2022 ITEM MEASURED QUANTITY OR TYPE OF GAUGE OR INSTRUMENT AND NOMINAL RANGE NOMINAL FREQUENCY CALIBRATION AND MEASUREMENT CAPABILITY EXPRESSED AS AN UNCERTAINTY (±) 2.1.2 Intermediate values (> 1 Ω to 1 MΩ) Fixed resistor, resistance box, multifunction calibrator 1 Ω to 100 Ω 2 10-7 R 100 Ω to 1 MΩ 4 10-6 R 2.1.3 High values (> 1 MΩ) Fixed resistor, resistance box, multifunction calibrator 1 MΩ to 100 MΩ 100 MΩ to 1 TΩ 2.2 resistance meters 2.2.1 Low values ( 1 Ω) Micro-ohm meter, multimeter, resistance bridge 0 Ω 1 Ω 2.2.2 Intermediate values (> 1 Ω to 1 GΩ) ohm meter, multimeter, resistance bridge 100 Ω to 1 kω 1 kω to 100 kω 100 kω to 1 MΩ 1 MΩ to 1 GΩ 2.2.3 High values (> 1 GΩ), multimeter, multifunctional transfer standard tera-ohmmeter 1 GΩ to 10 GΩ 10 GΩ to 100 GΩ 100 GΩ to 1 TΩ 3 current (up to 100A) 3.1 current sources. 3.1.1 Low values ( 0,1 ma) Current generator, multifunction calibrator. 0,1 µa to 1 µa 1 µa to 10 µa 10 µa to 100 µa 3.1.2 Intermediate values (> 0,1 ma to 20 A) Current generator, multifunction calibrator 0,1 ma to 1 ma 1 ma to 10 ma 10 to 100 ma 0,1A to 1 A 1 A to 20 A 3.1.3 High values (> 20 A to 100 A) Current generator. 6 10-6 R 2 10-3 R 0,3 µω 1 10-6 R 3 10-6 R 3 10-6 R 7 10-6 R 2 10-5 R 7 10-5 R 3 10-4 R 2 10-3 R 2 10-4 I 5 10-5 I 3 10-5 I 3 10-5 I 3 10-5 I 3 10-5 I 3 10-5 I 3 10-5 I 20 A to 100 A 2 10-4 I Original date of accreditation: 31 May 2017 Page 2 of 6 The CMC, expressed as an expanded uncertainty of measurement, is stated as the standard uncertainty of measurement multiplied by a coverage factor k = 2, corresponding to a confidence level of approximately 95% SANAS Page 8 of 13
ANNEXURE A Facility Number: 100 Date of Issue: 31 May 2017 Expiry Date: 30 May 2022 ITEM MEASURED QUANTITY OR TYPE OF GAUGE OR INSTRUMENT AND NOMINAL RANGE NOMINAL FREQUENCY 3.2 current meters. 3.2.1 Low values ( 0,1 ma) pico ammeter, nano ammeter, multimeter. 0,1 µa to 1 µa 1 µa to 10 µa 10 µa to 100 µa CALIBRATION AND MEASUREMENT CAPABILITY EXPRESSED AS AN UNCERTAINTY (±) 2 10-4 I 5 10-5 I 3 10-5 I 3.2.2 Intermediate values (> 0,1 ma to 20 A) multimeter, current meter 1 ma to 10 ma 3 10-5 I 10 to 100 ma 3 10-5 I 0,1A to 1 A 3 10-5 I 1 A to 20 A 3 10-5 I 4 Impedance (up to 200 khz range) 4.2 Capacitance 4.2.1 Capacitance and dissipation factor for low loss capacitors, standard capacitor (sealed, dry-nitrogen, fused silica) 1 pf to 100 nf 1 µf 1 µf to 100 µf 1 µf to 1 µf 1 µf 10 µf to 100 µf 10 khz 6 10-6 C 5 10-5 C 7 10-3 C 8 10-3 C 5 10-3 C 8 10-3 C 4.2.2 Capacitance and dissipation factor for dielectric capacitors, fixed capacitor, switched capacitor, capacitance box 1 pf to 100 nf 10 µf 1 pf to 100 nf 1 µf to 10 µf 10 pf to 10 µf 10 µf 10 khz 10 khz 6 10-6 C 4 10-4 C 5 10-4 C 7 10-3 C 5 10-3 C 8 10-3 C 4.2.3 Capacitance and dissipation factor for transformed capacitors, fixed capacitor, switched capacitor 1 nf to 100 nf 1 µf 10 µf 10 nf to 100 nf 1 µf to 10 µf 10 pf to 10 µf 10 µf 4.2.4 Meters, capacitance bridge, LCR meter 10 khz 10 khz 1 nf to 100 µf 1 µf to 10 µf to Original date of accreditation: 31 May 2017 Page 3 of 6 6 10-6 C 5 10-5 C 4 10-4 C 5 10-4 C 7 10-3 C 5 10-3 C 8 10-3 C 4 10-4 C 6 10-4 C The CMC, expressed as an expanded uncertainty of measurement, is stated as the standard uncertainty of measurement multiplied by a coverage factor k = 2, corresponding to a confidence level of approximately 95% SANAS Page 9 of 13
ANNEXURE A Facility Number: 100 Date of Issue: 31 May 2017 Expiry Date: 30 May 2022 ITEM 4.3 Inductance MEASURED QUANTITY OR TYPE OF GAUGE OR INSTRUMENT AND NOMINAL RANGE NOMINAL FREQUENCY CALIBRATION AND MEASUREMENT CAPABILITY EXPRESSED AS AN UNCERTAINTY (±) 4.3.1 Low values (< 1 mh) self inductance and equivalent series resistance, fixed inductor, variable inductor, inductance box 4.3.2 100 µh 3 10-4 L Intermediate values ( 1 mh to 1 H) self inductance and equivalent series resistance, fixed inductor, variable inductor, inductance box 1 mh 10 mh 100 mh 1 H 1 H 100 Hz 2 10-4 L 2 10-4 L 2 10-4 L 3 10-4 L 3 10-4 L 4.3.3 High values (> 1 H) self inductance and equivalent series resistance, fixed inductor, variable inductor, inductance box 10 H 100 Hz 4.3.5 Meters, LCR meter 100 µh 1 mh 10 mh 100 mh 1 H 1 H 10 H 5 AC voltage (up to the MHz range) 5.1 AC/ voltage transfer 100 Hz 100 Hz 5.1.1 AC/ transfer difference at low voltages (typically below or equal to 0.5 V) 2 mv to 200 mv 2 mv to 200 mv 200 mv to 0,5 V 10 Hz to 300 khz 300 khz to 1 MHz 10 Hz to 1 MHz 5.1.2 AC/ transfer difference at low voltages (typically above 0.5 V to 5 V) 4 10-4 L 4 10-4 L 3 10-4 L 2 10-4 L 2 10-4 L 2 10-4 L 3 10-4 L 3 10-4 L 4 10-4 L 4 10-4 U 9 10-4 U 6 10-5 U 0,5 V to 5 V 10 Hz to 1 MHz 6 10-5 U 5.1.3 AC/ transfer difference at higher voltages (typically 5 V) 5 V to 30 V 5 V to 30 V 30 V to 1000 V 5.2 AC voltage up to 1100 V 5.2.1 Sources, multifunction calibrator 2 mv to 200 mv 200 mv to 30 V 200 mv to 30 V 30 V to 1000 V 10 Hz to 100 Hz to 1 MHz 10 Hz to 10 Hz to 1 MHz 10 Hz to to 1 MHz 10 Hz to Original date of accreditation: 31 May 2017 Page 4 of 6 3 10-5 U 1 10-4 U 7 10-5 U 1 10-3 U 4 10-5 U 2 10-4 U 7 10-5 U The CMC, expressed as an expanded uncertainty of measurement, is stated as the standard uncertainty of measurement multiplied by a coverage factor k = 2, corresponding to a confidence level of approximately 95% SANAS Page 10 of 13
ANNEXURE A Facility Number: 100 Date of Issue: 31 May 2017 Expiry Date: 30 May 2022 ITEM MEASURED QUANTITY OR TYPE OF GAUGE OR INSTRUMENT AND NOMINAL RANGE NOMINAL FREQUENCY CALIBRATION AND MEASUREMENT CAPABILITY EXPRESSED AS AN UNCERTAINTY (±) 5.2.2 Meters, ac voltmeter, 2 mv to 200 mv 2 mv to 200 mv 200 mv to 30 V 200 mv to 30 V 30 V to 1000 V 6 AC current 10 Hz to 300 khz 300 khz to 1 MHz 10 Hz to to 1 MHz 10 Hz to 5 10-4 U 1 10-3 U 4 10-5 U 1 10-4 U 7 10-5 U 6.1 AC/ current transfer 6.1.1 AC/ transfer difference 10 ma to 20 A 20 Hz to 10 khz 8 10-5 I 6.2 AC current up to 100A 6.2.1 Sources, Multifunction calibrator 10 ma to 20 ma 20 ma to 200 ma 200 ma to 2 A 2 A to 11 A 20 Hz to 10 khz 20 Hz to 10 khz 20 Hz to 10 khz 20 Hz to 10 khz 6.2.2 Meters, ac meter, multimeter, multifunction transfer standard 10 ma to 200 ma 20 Hz to 5 khz 10 ma to 200 ma 5 khz to 10 khz 200 ma to 2 A 20 Hz to 5 khz 200 ma to 2 A 5 khz to 10 khz 2 A to 11 A 20 Hz to 2 A to 11 A to 10 khz 7 AC power 7.1 AC power and energy 7.1.1 Single phase Energy Meter (f< = 400 Hz) 0,01 A to 100 A 60 V to 250 V 7.1.3 a Three phase Energy Meter (Active) 0,01 A to 100 A 110 V to 415 V 7.1.3 b Three phase Energy Meter (Reactive) 0,01 A to 100 A 110 V to 415 V 6 10-5 I 9 10-5 I 2 10-4 I 6 10-4 I 5 10-4 I 2 10-3 I 9 10-4 I 9 10-3 I 6 10-4 I 4 10-3 I 50 HZ 8 10-4 E @ 1 PF 15 10-4 E @ 0,5 PF 50 HZ 8 10-4 E @ 1 PF 15 10-4 E @ 0,5 PF 50 HZ 8 10-4 E @ 0 PF 15 10-4 E @ 0,8 PF Original date of accreditation: 31 May 2017 Page 5 of 6 The CMC, expressed as an expanded uncertainty of measurement, is stated as the standard uncertainty of measurement multiplied by a coverage factor k = 2, corresponding to a confidence level of approximately 95% SANAS Page 11 of 13
ANNEXURE A Facility Number: 100 Date of Issue: 31 May 2017 Expiry Date: 30 May 2022 ITEM MEASURED QUANTITY OR TYPE OF GAUGE OR INSTRUMENT AND NOMINAL RANGE NOMINAL FREQUENCY CALIBRATION AND MEASUREMENT CAPABILITY EXPRESSED AS AN UNCERTAINTY (±) 8 High voltage and current 8.1 High voltage (for voltages < 1100 V see 1) 8.1.1 High voltage sources 1 kv to 40 kv 1 10-2 U 8.3 AC high voltage and voltage transformers (for voltages <1 100 V see 5.2 ) 8.3.1 Sources 1 kv to 28 kv 1 10-2 U A Thermometry equipment (Electrical equivalent Indicators -273 ºC to 2 000 ºC 0,1 K Transmitters -273 ºC to 2 000 ºC 0,1 K Calibrators -273 ºC to 2 000 ºC 0,1 K Cold junction compensation 0 ºC to 30 ºC 0,1 K B Oscilloscopes up to 250 MHz Voltage 1 mv/div to 50 V/div 0,5 % AC Voltage 1 mv/div to 50 V/div 0,5 % Horizontal time-base 2 ns/div to 5 sec/div 0,5 % Bandwidth 50 khz to 250 MHz 5 % Original date of accreditation: 31 May 2017 Page 6 of 6 The CMC, expressed as an expanded uncertainty of measurement, is stated as the standard uncertainty of measurement multiplied by a coverage factor k = 2, corresponding to a confidence level of approximately 95% ISSUED BY THE SOUTH AFRICAN NATIONAL ACCREDITATION SYSTEM Field Manager SANAS Page 12 of 13
ADDENDUM 1: Amendment Record Proposed By: Section Change STC / FM All Complete revision SANAS Page 13 of 13