rf+ voltage voltage

rf+ voltage voltage, Total:200 items.

The international standard classification for "rf+ voltage voltage" includes: Chipless working equipment , Electrical engineering in general , Power stations in general , Commercial vehicles .

The Chinese standard classification for "rf+ voltage voltage" includes: Radio Measurement , Metal forming machinery , Basic standards and general methods , , New energy vehicle and other automobiles .

National Metrological Verification Regulations of the People's Republic of China

JJG 494-2005 Verification Regulation of High Voltage Electrostatic Voltmeters
JJG 494-1987 High Voltage Electrostratic Voltmeter
JJG 250-1990 Verification Regulation of Electronic Voltmeter

Hebei Provincial Standard of the People's Republic of China

DB13/T 2005-2014 Resistance divider electronic voltage transformer

Professional Standard - Aerospace

QJ 192-1975 Series of Voltage and Current for Low-voltage Small-power DC Stabilized Power Supply

Guangdong Provincial Standard of the People's Republic of China

DB44/T 991-2012 Voltage Sounder and Voltage Buzzer

Professional Standard - Machinery

JB/T 1808-1995 Electrode Extrusion Hydraulic Press
JB/T 10372-2002 Hydraulic Fluid-pressure Switch
JB/T 7083-2013 Impulse-voltage tester for low-voltage electrical installations
JB/T 1808-2005 Electrode extrusion press
JB/T 7482-1994 Piezoelectric pressure sensor
JB/T 7083-1993 Impulse Voltage Testing Instruments for Low Voltage Apparatus
JB/T 10372-2014 Hydraulic-fluid-power-Pressure Switch

Military Standard of the People's Republic of China-General Armament Department

GJB 8818-2015 Calibration regulations for high-voltage and high-frequency electronic voltmeters

Military Standard of the People's Republic of China-Commission of Science,Technology and Industry for National Defence

GJB/J 5413-2005 Verification regulation for electronic voltmeter of high frequency and voltage

General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China

GB/T 35727-2017 Guideline for standard voltages of medium and low voltage DC distribution system
GB/T 31466-2015 Voltage ratings of electric vehicles high voltage electricity system
GB/T 35727-2017(英文版) Guidelines for Medium and Low Voltage DC Distribution Voltage
GB/T 18481-2001 Power quality--Temporary and transient overvoltages

未注明发布机构

FORD FLTM BB 101-12-2000 TEST OF AUTOMOTIVE ELECTRICAL CABLE FOR DURATION VOLTAGE AND BREAKDOWN VOLTAGE

Taiwan Provincial Standard of the People's Republic of China

CNS 9094-1982 Series Reactors for High Voltage Power Capacitors

Group Standards of the People's Republic of China

T/ZSM 0013-2022 Wire connection tool-Rechargeable battery hydraulic crimping tool

Professional Standard - Aviation

HB/T 6144-2020 Crimping requirement for wires of crimp electrical connectors

Defense Logistics Agency

DLA DSCC-VID-V62/03634 REV B-2012 MICROCIRCUIT, LINEAR, ULTRALOW-NOISE, HIGH PSRR, FAST RF 200-mA LOW-DROPOUT LINEAR REGULATORS, MONOLITHIC SILICON
DLA SMD-5962-09209-2009 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, FIXED VOLTAGE REGULATOR
DLA SMD-5962-08246-2009 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, FIXED VOLTAGE REGULATOR
DLA SMD-5962-09236-2009 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, FIXED VOLTAGE REGULATOR
DLA SMD-5962-08246 REV A-2011 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, FIXED VOLTAGE REGULATOR
DLA SMD-5962-09209 REV A-2011 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, FIXED VOLTAGE REGULATOR
DLA DESC-DWG-88057-1989 RESISTOR, VOLTAGE SENSITIVE (VARISTOR)
DLA SMD-5962-05220-2008 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, ADJUSTABLE AND FIXED VOLTAGE REGULATOR
DLA SMD-5962-09216 REV B-2011 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, ADJUSTABLE AND FIXED VOLTAGE REGULATOR
DLA MIL-T-27/36 C-2012 TRANSFORMER, POWER, STEP DOWN AND STEP UP
DLA MIL-T-27/265 B-2009 TRANSFORMER, POWER, STEP DOWN AND STEP UP
DLA MIL-PRF-27/194 B-2008 TRANSFORMER, POWER, STEPDOWN AND STEP-UP
DLA MIL-T-27/181 C-2009 TRANSFORMER, POWER, STEP-DOWN AND STEP-UP
DLA MIL-T-27/99 C-2012 TRANSFORMER, POWER, STEP-DOWN
DLA MIL-T-27/227 A-2009 TRANSFORMER, POWER, STEP-DOWN
DLA MIL-T-27/295 C-2012 TRANSFORMER, POWER, STEP-DOWN
DLA MIL-PRF-27/192 A-2008 TRANSFORMER, POWER, STEPDOWN
DLA MIL-PRF-27/33 A-2008 TRANSFORMER, POWER, STEP-UP
DLA MIL-PRF-27/134 B-2009 TRANSFORMER, POWER, STEP-DOWN
DLA MIL-T-83720/8 B VALID NOTICE 4-2011 Transformer, Power Step-Up
DLA MIL-PRF-27/27 A-2008 TRANSFORMER, POWER, STEP DOWN
DLA MIL-T-27/189 A NOTICE 2-1998 TRANSFORMERS AND INDUCTORS (AUDIO, POWER AND HIGH-POWER PULSE), INDUCTOR, POWER, TF5S04ZZ
DLA SMD-5962-09211-2010 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, ADJUSTABLE VOLTAGE REGULATOR
DLA SMD-5962-10235 REV A-2012 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, ULTRA LOW DROPOUT, ADJUSTABLE AND FIXED OUTPUT, VOLTAGE AGE REGULATOR
DLA SMD-5962-09210 REV A-2011 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, ADJUSTABLE VOLTAGE REGULATOR
DLA MIL-T-27/156 A VALID NOTICE 4-2004 TRANSFORMER, POWER, STEP-DOWN, TF4S03AJ
DLA MIL-T-27/184 B VALID NOTICE 3-2011 Transformer, Power, Step-Down, TF4S03AH
DLA MIL-T-27/140B (1)-1997 TRANSFORMERS, POWER, STEP-DOWN, TF4S03YY
DLA SMD-5962-09210-2009 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, ADJUSTABLE VOLTAGE REGULATOR
DLA SMD-5962-09212 REV D-2010 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, ADJUSTABLE VOLTAGE REGULATOR
DLA MIL-T-27/183 B VALID NOTICE 4-2011 Transformer, Power, Step-Down and Step-Up, TF45S03JA
DLA SMD-5962-10235-2010 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, ULTRA LOW DROPOUT, ADJUSTABLE AND FIXED OUTPUT, VOLTAGE AGE REGULATOR
DLA SMD-5962-98514 REV D-2012 MICROCIRCUIT, HYBRID, LINEAR, NEGATIVE VOLTAGE REGULATOR
DLA SMD-5962-09213-2011 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, ADJUSTABLE VOLTAGE REGULATOR
DLA MIL-PRF-27/155 B VALID NOTICE 1-2001 TRANSFORMER, POWER, STEPDOWN, TF4S03EA
DLA MIL-T-27/148 A VALID NOTICE 4-2011 Transformer, Power, Step-Down, TF4S03HA
DLA MIL-T-27/154 VALID NOTICE 4-2011 Transformer, Power, Step-Down, TF4S03EB
DLA MS16403 REV D VALID NOTICE 1-1988 TRANSFORMER, POWER, STEP-DOWN AND STEP-UP, TYPE TF4RX03JB221
DLA SMD-5962-09208 REV A-2011 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, ADJUSTABLE VOLTAGE REGULATOR
DLA SMD-5962-09208-2009 MICROCIRCUIT, HYBRID, LINEAR, POSITIVE, LOW DROPOUT, ADJUSTABLE VOLTAGE REGULATOR
DLA DSCC-DWG-01014 REV B-2009 CONNECTOR, PLUG, ELECTRICAL, RF, SERIES TNC, FOR LOW SMOKE CABLES

Military Standards (MIL-STD)

MIL MIL-G-46898-1974 GASKETING, RF AND PRESSURE (NO S/S DOCUMENT)
MIL MIL-T-27/181C-2009 Transformer, Power, Step-Down and Step-Up
MIL MIL-PRF-27/194B-2008 TRANSFORMER, POWER, STEPDOWN AND STEP-UP
MIL MIL-PRF-83530/1C-2008 Resistors, Voltage Sensitive (Varistors) Style RVS10
MIL MIL-T-27/151C-2012 Transformer, Power, Step-Down
MIL MIL-T-27/223C-2012 Transformers, Power, Step-Down
MIL MIL-T-27/291C-2012 Transformer, Power, Step-Down
MIL MIL-T-27/99C-2012 Transformer, Power, Step-Down
MIL MIL-PRF-27/134B-2009 Transformer, Power, Step-Down
MIL MIL-PRF-27/155C-2011 Transformers, Power, Stepdown
MIL MIL-T-27/295C-2012 Transformer, Power, Step-Down
MIL MIL-T-27/202B-2012 Transformers, Power, Step-Down
MIL MIL-T-27/265B-2009 Transformer, Power, Step Down and Step Up
MIL MIL-T-27/129B-2012 Transformer, Power, Step-Down and Step-Up
MIL MIL-PRF-27/27A-2008 Transformer, Power, Step Down
MIL MIL-PRF-27/193B-2008 TRANSFORMER, POWER, STEPDOWN
MIL MIL-PRF-27/33A-2008 Transformer, Power, Step-Up
MIL MIL-PRF-27/300D-2010 Transformers, Power, Stepdown
MIL MIL-PRF-27/192A-2008 TRANSFORMER, POWER, STEPDOWN
MIL MIL-PRF-27/195A-2008 TRANSFORMER, POWER, STEPDOWN
MIL MIL-PRF-27/157E-2010 Transformer Power, Stepdown,
MIL MIL-T-27/227A-2009 Transformer, Power, Step-Down
MIL MIL-PRF-27/27-1975 TRANSFORMER, POWER, STEP-DOWN, TF5V03ZZ314
MIL MIL-T-27/154-1977 TRANSFORMER, POWER, STEP-DOWN, TF4S03EB
MIL MIL-T-60206-1965 TRANSFORMER, POWER, STEP DOWN, 10525900
MIL MIL-T-27/192-1977 TRANSFORMER, POWER, STEPDOWN, TF5S03ZZ
MIL MIL-T-27/227-1978 TRANSFORMER, POWER, STEP-DOWN, TF5T03ZZ
MIL MIL-T-60193-1965 TRANSFORMER, POWER, STEP DOWN, 10525915

Swedish Institute for Standards

SIS SEN 43 03 14-1963 Flexible R.F. Coaxial Cable
SIS SEN 43 03 15-1963 Flexible R.F. Coaxial Cable
SIS SEN 43 03 18-1963 Flexible R.F. Coaxial Cable
SIS SEN 43 03 10-1963 Flexible R.F. Coaxial Cable
SIS SEN 43 03 28-1963 Flexible R.F. Coaxial Cable
SIS SEN 43 03 12-1963 Flexible R.F. Coaxial Cable
SS-EN 16289:2013 Glass packaging - Screw finishes for pressure capsules - MCA 7,5 RF finish
SIS SS IEC 726:1983 Power transformers - Dry-type power transformers
SIS SEN 43 03 29-1965 Flexible R.F. coaxial cable, type HK 50-12-1
SIS SS 427 01 29-1990 Power transformers — Dry-type power transformers
SIS SS 427 01 29-1991 Power transformers — Dry-type power transformers
SIS SS 428 06 05-1980 Safety switches for max 1000 V a.c
SIS SEN 43 03 21-1964 Flexible R.F. coaxial cable, type HK 75-4-3 A
SIS SEN 43 03 27-1964 Flexible R.F. coaxial cable, type HK 75-4-2

European Committee for Standardization (CEN)

prEN 50109-3-2-1992 Hand crimping tools; tools for the crimp termination of electrical cables and wires for low frequency and radio frequency applications; part 3-2: specification for hand crimpling tools for centre contacts of RF connectors, series SMZ
EN 2591-225:2007 Aerospace series - Elements of electrical and optical connection - Test methods - Part 225: RF high potential withstanding voltage

Association Francaise de Normalisation

NF EN 16289:2013 Glass packaging - Screw caps for pressure caps - MCA 7.5 RF cap
NF H35-129*NF EN 16289:2013 Glass packaging - Screw finishes for pressure capsules - MCA 7,5 RF finish
NF C93-563-2-4*NF EN 50109-2-4:2004 Hand crimping tools - Tools for the crimp termination of electric cables and wires for low frequency and radio frequency applications - Part 2-4 : particular requirements for centre contacts of RF connectors, series SMZ.
NF UTE C93-613:1979 Piezoelectric Devices - Piezoelectric Filters - User's Guide to Piezoelectric Crystal Filters
NF C 15-150-1:1998 Low voltage signs and low voltage supply of high voltage signs (called with neon-tube)
NF C42-164*NF EN 60618:1998 Inductive voltage dividers.

Bureau of Indian Standards

IS 10230-1-1982 IF, RF transformers and inductors (coils): Part 1 General requirements and tests (Superseding IS:1512-1969)
IS 1512-1969 Testing and general requirements for IF transformers and RF coils
IS/IEC 60044-7-1999 Instrument Transformers Part 7 Electronic Voltage Transformers
IS 19053-2024 DC Voltages for HVDC Grids

German Institute for Standardization

DIN EN 2591-225:2009 Aerospace series - Elements of electrical and optical connection - Test methods - Part 225: RF high potential withstanding voltage; German and English version EN 2591-225:2007
DIN EN 129000:1994 Generic specification; fixed RF wound inductors; German version EN 129000:1993
DIN 57100-736:1983 Erection of power installations with rated voltages up to 1000 V; low voltages circuits in high-voltage switchboards [VDE Specification]
DIN IEC/TS 63471:2024-10*VDE V 0676-115-3471:2024-10 DC voltages for HVDC grids
DIN EN 129000/A1:1996 Generic specification; Fixed RF wound inductors; German version EN 129000:1993/A1:1995
DIN EN 60618:1999 Inductive voltage dividers (IEC 60618:1978 + A1:1981 + A2:1997); German version EN 60618:1997 + A2:1997
DIN EN 16289 E:2011-05 Draft Document - Glass packaging - Screw finishes for pressure capsules - MCA 7.5 RF finish; German version prEN 16289:2011
DIN EN 50482 E:2006-04 Draft Document - Instrument transformers - Three-phase inductive voltage transformers having U<(Index)m> up to 52 kV; German version prEN 50482:2005

Deutsche Vereinigung des Gas- und Wasserfachs

DVGW W 633:2004-10 High and low voltage installations in waterworks — Transformers

British Standards Institution (BSI)

BS EN 2591-225:2007 Aerospace series - Elements of electrical and optical connection - Test methods - Part 225: RF high potential withstanding voltage
BS EN 16289:2013 Glass packaging. Screw finishes for pressure capsules. MCA 7,5 RF finish
BS IEC 61196-9:2014 Coaxial communication cables. Sectional specification for RF flexible cables
BS EN IEC 60076-22-5:2021 Power transformers. Power transformer and reactor fittings. Electric pumps for transformers
BS EN IEC 60076-22-6:2021 Power transformers. Power transformer and reactor fittings. Electric fans for transformers
BS PD IEC TS 63471:2023 DC voltages for HVDC grids
BS EN IEC 60076-24:2020 Power transformers. Power transformer and reactor fittings. Electric pumps for transformers
BS IEC 60076-15:2015 Power transformers. Gas-filled power transformers
BS 3026:1958 Specification. Voltages for high-voltage d.c. transmission systems
BS EN 60368-2-2:1999 Piezoelectric filters. Guide to the use of piezoelectric filters. Piezoelectric ceramic filters
BS 7697:1993 Nominal voltages for low voltage public electricity supply systems
BS EN 61243-5:2001 Live working - Voltage detectors - Voltage detecting systems (VDS)

Instituto Colombiano de Normas Técnicas y Certificación

ICONTEC 2207-1986 Electronics. voltage transformer

Association for Electrical, Electronic & Information Technologies (VDE)

VDE 0414-2-1994*DIN VDE 0414-2:1994 Instrument transformers; Voltage transformers (IEC 186 :1987 A1:1988, modified)
VDE 0682-401 A1 E*DIN VDE 0682-401 A1:2004-12 Live working – Voltage detectors – Part 3: Two-pole low-voltage type

Polski Komitet Normalizacyjny (PKN)

PN E06551-1985 Yoltage transformers

Korean Agency for Technology and Standards (KATS)

KS C IEC 60186:2003 Voltage transformers
KS C IEC 60186:2015 Voltage transformers
KS B 6894-2012 Relief valve for hydraulic elevators
KS C IEC 60618-2013(2018) Inductive voltage dividers
KS C 3324-1982 High-voltage drop wires for pole transformer
KS C 3324-2002 High-voltage drop wires for pole transformer
KS R 5013-2002 NOMINAL VOLTAGES AND TEST VOLTAGES FOR AUTOMOTIVE ELECTRIC EQUIPMENTS
KS C 6107-2013 Methods of measurement of radio influence voltage (RIV) of high-voltage apparatus

Austrian Standards

ONORM E 1100 Teil.2-1990 Standard voltages; nominal voltages for low voltage public electricity supply systems

Spanish Association for Standardization (UNE)

UNE 21088-2:1995 ERRATUM VOLTAGE TRANSFORMERS
UNE 21088-2:1995 VOLTAGE TRANSFORMERS
UNE 211620:2020 Distribution cables with extruded insulation, of rated voltage from 3.6 / 6 (7.2) kV up to 20.8 / 36 (42) kV inclusive. Single core and single core with XLPE insulation assembled cables. Cables with aluminium tape screen and polyolefin compound cover (...
UNE 21-301-1991 Rated voltage of low voltage distribution network
UNE 21587:1996 INSTRUMENT TRANSFORMERS. THREE-PHASE VOLTAGE TRANSFORMERS FOR VOLTAGE LEVELS HAVING Um UP TO 52 KV.
UNE-EN 60044-5:2005 Instrument transformers -- Part 5: Capacitor voltage transformers
AENOR UNE 21327:1976 ELECTRONIC VOLTMETERS
UNE-HD 620-9E:2012/1M:2022 Distribution cables with extruded insulation for rated voltages from 3,6/6 (7,2) kV up to and including 20,8/36 (42) kV. Part 9: HEPR insulated single core cables, and single core pre-assembled cables. Section E: Cables with polyolefin compound sheath ...
UNE-HD 620-10E:2012/1M:2020 Distribution cables with extruded insulation for rated voltages from 3,6/6 (7,2) kV up to and including 20,8/36 (42) kV. Part 10: XLPE insulated single core, and single core pre-assembled cables. Section E: Cables with polyolefin compound sheath (types...

Standard Association of Australia （SAA）

AS 4542.1:1999(R2016) Consumer television interfaces - PAL RF
AS 4542.1:1999 Consumer television interfaces - PAL RF

Türk Standardları Enstitüsü

TS 718-1978 VOLTAGE TRANSFORMERS
TS 3472-1980 ELECTRONIC VOLTMETERS

National Standardisation Body (ASRO)

SR CEI 186+A1-1996 Voltage transformers

Ente Nazionale Italiano di Unificazione

UNI EN 16289:2013 Glass packaging - Screw finishes for pressure capsules - MCA 7,5 RF finish

Czech Standards Institute (UNMZ)

CSN 35 1356-1997 Instrument transformers - Three-phase voltage transformers for voltage levels having Um up to 52 kV
CSN 50 0452-1988 Condenser páper. Determination of breakdown voltage at alternating (50 Hz) and direct voltage

Institute of Electrical and Electronics Engineers (IEEE)

IEEE C57.168-2023 IEEE Guide for Low-Frequency Dielectric Testing for Distribution, Power, and Regulating Transformers
IEEE Std C57.168-2023 IEEE Guide for Low-Frequency Dielectric Testing for Distribution, Power, and Regulating Transformers
IEEE 176-1987 Piezoelectricity
IEEE Std C62.41-1991 IEEE Recommended Practice on Surge Voltages in Low-Voltage AC Power Circuits
IEEE Std C37.29-1981 Low-voltage ac power circuit protectors used in enclosures
ANSI/IEEE Std C62.41-1980 IEEE Guide for Surge Voltages in Low-Voltage AC Power Circuits
IEEE 404-1993 Cable joints for use with extruded dielectric cable rated 5000 V through 138000 V and cable joints for use with laminated dielectric cable rated 2500 V through 500000 V

Yugoslav Association for Standardization

JUS N.C6.134-1993 Coaxial cables for cable distribution systems and common antena systems RF 75-5-6 F/V ,RF 75-5-6 S/V,RF75-5-6 F/P,RF 75-5-6 S/P
JUS N.H1.018-1987 Power transformers. Dry-type povver transformers

Japanese Industrial Standards Committee (JISC)

JIS C 4802:1990 Discharge coils for high voltage power capacitors
JIS D 5005:1989 Nominal voltages and test voltages for automotive electric equipments

Gosstandart of Russia

GOST R 71590-2024 Thermistors. Method for measuring stabilization voltage and determining the change in stabilization voltage with change in current
GOST 21342.9-1976 Varistors. Method of measuring voltage and current

Danish Standards Foundation

DS/IEC 618:1983 Inductive voltage dividers with Amendment Nr.1
DANSK DS/IEC/IEEE 63253-5713-8:2024 Station Service Voltage Transformers (SSVT)

Society of Automotive Engineers (SAE)

SAE AIR1404 DC Resistivity Vs RF Impedance of EMI Gaskets

Asociación Española de Normalización (AENOR)

AENOR UNE-EN 16289:2013 Glass packaging - Screw finishes for pressure capsules - MCA 7,5 RF finish

International Electrotechnical Commission (IEC)

IEC 60217:1967 Electronic voltmeters
IEC 60076-24:2020 Power transformers - Part 24: Specification of voltage regulating distribution transformers (VRDT)
IECQ CS 042200-GB0001-2015 Varistors: Metal Oxide Varistor
IEC/IEEE 63253-5713-8:2024 Station Service Voltage Transformers (SSVT)
IEC 60076-22-6:2021 Power transformers - Part 22-6: Power transformer and reactor fittings - Electric fans for transformers

GCC Standardization Organization

GSO IEC 61243-5:2014 Live working - Voltage detectors - Part 5: Voltage detecting systems (VDS)

Comitato Elettrotecnico Italiano

CEI UNEL 35023:2020 Power cables for nominal voltage U equal to 1 kV - Voltage drops
CEI EN IEC 60076-24:2021 Power transformers Part 24: Specification of voltage regulating distribution transformers (VRDT)

National Electrical Manufacturers Association（NEMA)

NEMA HVM S1-2018 High Voltage and Medium Voltage Motors

Argentine Institute of Standardization

IRAM 2001-N.P.-1946 Voltage and frequency

Magyar Szabványügyi Testület

MSZ 7254-1970 Electrical insulating material arc detection high voltage, low voltage arc

Associação Brasileira de Normas Técnicas

ABNT P-EB-157-1963 Multi-level radio noise voltage power transformers and distributors

European Committee for Electrotechnical Standardization（CENELEC）

EN IEC 60076-22-6:2021 Power transformers - Part 22-6: Power transformer and reactor fittings - Electric fans for transformers

Electronic Components, Assemblies and Materials Association

ECA 272-1963 Voltage Jump for Voltage Regulator and Reference Tubes, Definition and Measurement of