Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
GB/T 20840 consists of the following parts under the general title Instrument transformers:
——Part 1: General requirements;
——Part 2: Additional requirements for current transformers;
——Part 3: Additional requirements for inductive voltage transformers;
——Part 4: Additional requirements for combined transformers;
——Part 5: Additional requirements for capacitor voltage transformers;
——Part 6: Additional general requirements for low-power instrument transformers;
——Part 7: Electronic voltage transformers;
——Part 8: Electronic current transformers;
——Part 9: Digital interface for instruments transformers.
This is Part 6 of GB/T 20840.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part shall be used together with GB/T 20840.1-2010 Instrument transformers - Part 1: General requirements. This part follows the compiling structure of GB/T 20840.1 and is an addition and modification of the corresponding clauses thereof. The clauses of GB/T 20840.1 not mentioned in this part are applicable to this part as long as they are reasonable. Where "addition", "modification" or "substitution" is indicated in this part, it means that the relevant provisions of GB/T 20840.1 have been adapted accordingly in this part.
For clauses, subclauses, figures, tables, notes and annexes added on the basis of GB/T 20840.1-2010, this part adopts the following numbering form:
——clauses, subclauses, figures and tables are numbered from 601;
——annexes are numbered 6A and 6B.
This part has been redrafted and modified in relation to IEC 61869-6:2016 Instrument transformers - Part 6: Additional requirements for current transformers.
The following structural changes have been made with respect to IEC 61869-6:2016:
——the title of 3.2 in IEC 61869-6:2016 is deleted, with its contents incorporated into 3.3, and the title of 3.3 is changed to "Definitions related to current or voltage ratings";
——7.2.1.1 of IEC 61869-6:2016 is adjusted to 7.2.1.2 of this part;
——7.3.1, 7.3.4 and 7.3.5 of IEC 61869-6:2016 are adjusted as 7.3.2, 7.3.6 and 7.3.7 of this part;
——the sequence of Annex 6B and Annex 6C of IEC 61869-6:2016 is exchanged in this part.
The main technical differences of this part from IEC 61869-6:2016 and their justifications are as follows:
——the adjustment on technical differences are made for the normative references of this Part to adapt to the technical conditions in China. The adjustments are mainly reflected in Clause 2 "Normative references", which are shown as follows:
IEC 60812:2006 is replaced by GB/T 7826, which is identical to the international standard;
IEC 61000-4-11:2004 is replaced by GB/T 17626.11, which is identical to the international standard;
IEC 61000-4-29:2000 is replaced by GB/T 17626.29, which is identical to the international standard;
IEC 61869-1:2007 is replaced by GB/T 20840.1-2010, which is modified in relation to the international standard;
IEC 61869-2:2012 is replaced by GB/T 20840.2-2014, which is modified in relation to the international standard;
IEC 61869-3:2011 is replaced by GB/T 20840.3-2013, which is modified in relation to the international standard;
——in order to adapt to the voltage conditions in China, in 5.3.601.2, the preferred a.c. voltage is changed from "100V~230V" to "110V, 220V";
——in order to adapt to national conditions of China, in Table 11 of 7.1.2, "gas dew point test" and "measurement of capacitance and dielectric dissipation factor" are adjusted from special tests to routine tests;
——in order to adapt to the climatic conditions in China, in 7.2.601.1, the ambient air temperature during the test is changed from "10℃~30℃" to "5℃~40℃";
——in order to adapt to national conditions of China, in Annex 6A, Figure 6A.2 is drawn according to "fr=50Hz, fs=4,000Hz" instead of "fr=60Hz, fs=4,800Hz".
The following editorial changes have been made in this part:
——IEC 60044-7:1999, IEC 60050-321:1986, IEC 60050-421:1990, IEC 61869 (all parts), IEC 61869-7 and IEEE C37.92-2005 in bibliography of IEC 61869-6:2016 are deleted.
This part was proposed by China Electrical Equipment Industrial Association.
This standard is under the jurisdiction of National Technical Committee on Instrument Transformers of Standardization Administration of China (SAC/TC 222).
Instrument transformers - Part 6: Additional general requirements for low-power instrument transformers
1 Scope
This part of GB/T 20840 covers additional general technical requirements for low-power instrument transformers (LPIT) used for a.c. applications having rated frequencies from 15Hz to 100Hz or used for d.c. applications. This product standard is based on GB/T 20840.1, in addition to the relevant product specific standard.
This part does not cover the specification for the digital output format of instrument transformers.
This part defines the errors in case of analogue or digital output. The other characteristics of the digital interface for instrument transformers are specified in GB/T 20840.9 as an application of the standards, which details layered substation communication architecture.
This part considers additional requirements concerning bandwidth. The accuracy requirements on harmonics and requirements for the anti-aliasing filter are given in Annex 6A.4.
The general block diagram of single-phase LPIT is given in Figure 601.
According to the technology, it is not absolutely necessary that all parts described in Figure 601 are included in the instrument transformer.
As an example, for low-power passive transformers (LPITs without active electronic components), the blocks are composed only with passive components and there is no power supply.
Figure 601 General block diagram of a single-phase LPIT
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
Clause 2 of GB/T 20840.1-2010 is applicable with the following additions:
GB/T 7826 Analysis techniques for system reliability - Procedure for failure mode and effects analysis (FMEA) (GB/T 7826-2012, IEC 60812:2006, IDT)
GB/T 17626.11 Electromagnetic compatibility - Testing and measurement techniques - Voltage dips, short interruptions and voltage variations immunity tests (GB/T 17626.11-2008, IEC 61000-4-11:2004, IDT)
GB/T 17626.29 Electromagnetic compatibility - Testing and measurement techniques - Voltage dips, short interruptions and voltage variations on d.c. input power port immunity tests (GB/T 17626.29-2006, IEC 61000-4-29:2000, IDT)
GB/T 20840.1-2010 Instrument transformers - Part 1: General requirements (IEC 61869-1:2007, MOD)
GB/T 20840.2-2014 Instrument transformers - Part 2: Additional requirements for current transformers (IEC 61869-2:2012, MOD)
GB/T 20840.3-2013 Instrument transformers - Part 3: Additional requirements for inductive voltage transformers (IEC 61869-3:2011, MOD)
IEC 60068-2-6:2007 Environmental testing - Part 2-6: Tests - Test Fc: Vibration (sinusoidal)
IEC 60255-27:2013 Measuring relays and protection equipment - Part 27: Product safety requirements
IEC 60603-7-1:2011 Connectors for electronic equipment - Part 7-1: Detail specification for 8-way, shielded, free and fixed connectors
IEC 61000-4-1:2006 Electromagnetic compatibility (EMC) - Part 4-1: Testing and measurement techniques - Overview of IEC 61000-4 series
IEC 61000-4-2:2008 Electromagnetic compatibility (EMC) - Part 4-2: Testing and measurement techniques - Electrostatic discharge immunity test
IEC 61000-4-3:2006+IEC 61000-4-3:2006/AMD1:2007+IEC 61000-4-3:2006/AMD2:2010 Electromagnetic compatibility (EMC) - Part 4-3: Testing and measurement techniques - Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-4:2012 Electromagnetic compatibility (EMC) - Part 4-4: Testing and measurement techniques - Electrical fast transient/burst immunity test
IEC 61000-4-5:2014 Electromagnetic compatibility (EMC) - Part 4-5: Testing and measurement techniques - Surge immunity test
IEC 61000-4-6:2013 Electromagnetic compatibility (EMC) - Part 4-6: Testing and measurement techniques - Immunity to conducted disturbances, induced by radio-frequency fields
IEC 61000-4-7:2002+IEC 61000-4-7:2002/AMD1:2008 Electromagnetic compatibility (EMC) - Part 4-7: Testing and measurement techniques - General guide on harmonics and interharmonics measurements and instrumentation, for power supply systems and equipment connected thereto
IEC 61000-4-8:2009 Electromagnetic compatibility (EMC) - Part 4-8: Testing and measurement techniques - Power frequency magnetic field immunity test
IEC 61000-4-9:1993+IEC 61000-4-9:1993/AMD1:2000 Electromagnetic compatibility (EMC) - Part 4-9: Testing and measurement techniques - Section 9: Pulse magnetic field immunity test
IEC 61000-4-10:1993+IEC 61000-4-10:1993/AMD1:2000 Electromagnetic compatibility (EMC) - Part 4-10: Testing and measurement techniques - Section 10: Damped oscillatory magnetic field immunity test. Basic EMC Publication
IEC 61000-4-13:2002+IEC 61000-4-13:2002/AMD1:2009 Electromagnetic compatibility (EMC) - Testing and measurement techniques - Harmonics and interharmonics including mains signaling at a.c. power port, low frequency immunity test
IEC 61000-4-16:1998+IEC 61000-4-16:1998/AMD1:2001+IEC 61000-4-16:1998/AMD2:2009 Electromagnetic compatibility (EMC) - Part 4-16: Testing and measurement techniques - Test for immunity to conducted, common mode disturbances in the frequency range 0 Hz to 150 kHz
IEC 61000-4-18:2006+IEC 61000-4-18:2006/AMD1:2010 Electromagnetic compatibility (EMC) - Part 4-18: Testing and measurement techniques - Damped oscillatory wave immunity test
IEC 61025:2006 Fault tree analysis (FTA)
IEC 61076-2-101:2012 Connectors for electronic equipment - Product requirements - Part 2-101: Circular connectors - Detail specification for M12 connectors with screw-locking
IEC 61850-2:2003 Communication networks and systems in substations - Part 2: Glossary
IEC 61850-7-4:2010 Communication networks and systems for power utility automation - Part 7-4: Basic communication structure - Compatible logical node classes and data object classes
IEC/TR 61869-103:2012 Instrument Transformers - The use of instrument transformers for power quality measurement
IEC 62271-100:2008 High-voltage switchgear and controlgear - Part 100: Alternating current circuit-breakers
ISO/IEC/IEEE 21451-4:2010 Information technology - Smart transducer interface for sensors and actuators - Part 4: Mixed-mode communication protocols and Transducer Electronic Data Sheet (TEDS) formats
CISPR 11:2015 Industrial, scientific and medical equipment - Radio-frequency disturbance characteristics - Limits and methods of measurement
EN 50160:2010 Voltage characteristics of electricity supplied by public distribution systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 20840.1 and the following apply.
3.1 General definitions
3.1.601
low-power instrument transformer
LPIT
arrangement, consisting of one or more current or voltage transformer(s) which may be connected to transmitting systems and secondary converters, all intended to transmit a low power analogue or digital output signal to measuring instruments, meters and protective or control devices or similar apparatus
Example: An arrangement consisting of three current sensors, three voltage sensors connected to one merging unit delivering one digital output is considered an LPIT.
Note 1: LPITs are commonly called non-conventional instrument transformers (NCIT).
Note 2: The output power produced by these devices is typically lower than or equal to 1VA.
3.1.602
low-power current transformer
LPCT
low-power instrument transformer for current measurement
3.1.603
low-power voltage transformer
LPVT
low-power instrument transformer for voltage measurement
3.1.604
measuring LPIT
LPIT intended to transmit an output signal to measuring instruments and meters
3.1.605
protective LPIT
LPIT intended to transmit an output signal to protective and control devices
3.1.606
multipurpose LPIT
LPIT intended for both measurement and protection applications
3.1.607
electronic LPIT
LPIT that includes active components
3.1.608
passive LPIT
LPIT that includes only passive components
3.1.609
input signal
signal corresponding to the current or to the voltage applied between the primary terminals of the LPIT
3.1.610
primary sensor
electrical, optical or other device intended to provide information about the input signal in order to transmit it to the secondary converter, either directly or by means of a primary converter
3.1.611
primary converter
electrical, optical or other device that converts the signal coming from one or more primary sensors into a signal suitable for the transmitting system
3.1.612
primary power supply
auxiliary power supply to the primary converter and/or primary sensor
Note: May be combined with secondary power supply (see 3.1.620).
3.1.613
transmitting system
short- or long-distance coupling arrangement between primary and secondary parts intended to transmit the signal
Note: Depending on the technology used, the transmitting system may also be used for power transmission.
3.1.614
secondary converter
arrangement that converts the signal transmitted through the transmitting system into a signal proportional to the input signal, to supply measuring instruments, meters and protective or control devices
Note: For analogue output, the secondary converter directly supplies measuring instruments, meters and protective or control devices. For digital output, the secondary converter is connected to a merging unit before supplying the secondary equipment.
3.1.615
logical device merging unit
logical device (in the meaning of IEC 61850-7-4:2010) to do the time-coherent combination of logical nodes current transformer (TCTR) and/or logical nodes voltage transformer (TVTR) for building a standard digital output
3.1.616
merging unit, MU
physical device (IED according to IEC 61850-2:2003) in which a logical device merging unit is implemented
Note 1: The merging unit may be part of one of the instrument transformers in the field or may be a separate unit, for example, in the control room.
Note 2: The inputs of the merging unit may be proprietary or standardized.
3.1.617
stand-alone merging unit, SAMU
merging unit with standardized inputs (analogue or digital)
Example 1: SAMU may be used with instrument transformers for retrofit purposes.
Example 2: Digital input of the stand-alone merging unit may be specified according to former GB/T 20840.8-2007 digital output or according to GB/T 20840.9. This possibility ensures the compatibility between GB/T 20840.8-2007 and the new GB/T 20840 series.
3.1.618
merging unit clock input
electrical or optical input of the merging unit that may be used to synchronize several merging units if required
3.1.619
merging unit power supply
auxiliary power supply of the merging unit
Note: A merging unit power supply may be combined with the secondary power supply (see 3.1.620).
3.1.620
secondary power supply
auxiliary power supply of the secondary converter
Note: A secondary power supply may be combined with primary power supply (see 3.1.612) or a power supply of other instrument transformers.
Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 Normal and special service conditions 5 Ratings 6 Design and construction 7 Tests 601 Information to be given with enquiries, tenders and orders Annex 6A (Normative) LPIT frequency response and accuracy requirements for harmonics Annex 6B (Informative) Transient performances of low-power voltage transformers Annex 6C (Informative) Transient performances of low-power current transformers Annex 6D (Informative) Test circuits Annex 6E (Informative) Graph explaining the accuracy requirements for multi-purpose low-power current transformer Bibliography
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
GB/T 20840 consists of the following parts under the general title Instrument transformers:
——Part 1: General requirements;
——Part 2: Additional requirements for current transformers;
——Part 3: Additional requirements for inductive voltage transformers;
——Part 4: Additional requirements for combined transformers;
——Part 5: Additional requirements for capacitor voltage transformers;
——Part 6: Additional general requirements for low-power instrument transformers;
——Part 7: Electronic voltage transformers;
——Part 8: Electronic current transformers;
——Part 9: Digital interface for instruments transformers.
This is Part 6 of GB/T 20840.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part shall be used together with GB/T 20840.1-2010 Instrument transformers - Part 1: General requirements. This part follows the compiling structure of GB/T 20840.1 and is an addition and modification of the corresponding clauses thereof. The clauses of GB/T 20840.1 not mentioned in this part are applicable to this part as long as they are reasonable. Where "addition", "modification" or "substitution" is indicated in this part, it means that the relevant provisions of GB/T 20840.1 have been adapted accordingly in this part.
For clauses, subclauses, figures, tables, notes and annexes added on the basis of GB/T 20840.1-2010, this part adopts the following numbering form:
——clauses, subclauses, figures and tables are numbered from 601;
——annexes are numbered 6A and 6B.
This part has been redrafted and modified in relation to IEC 61869-6:2016 Instrument transformers - Part 6: Additional requirements for current transformers.
The following structural changes have been made with respect to IEC 61869-6:2016:
——the title of 3.2 in IEC 61869-6:2016 is deleted, with its contents incorporated into 3.3, and the title of 3.3 is changed to "Definitions related to current or voltage ratings";
——7.2.1.1 of IEC 61869-6:2016 is adjusted to 7.2.1.2 of this part;
——7.3.1, 7.3.4 and 7.3.5 of IEC 61869-6:2016 are adjusted as 7.3.2, 7.3.6 and 7.3.7 of this part;
——the sequence of Annex 6B and Annex 6C of IEC 61869-6:2016 is exchanged in this part.
The main technical differences of this part from IEC 61869-6:2016 and their justifications are as follows:
——the adjustment on technical differences are made for the normative references of this Part to adapt to the technical conditions in China. The adjustments are mainly reflected in Clause 2 "Normative references", which are shown as follows:
IEC 60812:2006 is replaced by GB/T 7826, which is identical to the international standard;
IEC 61000-4-11:2004 is replaced by GB/T 17626.11, which is identical to the international standard;
IEC 61000-4-29:2000 is replaced by GB/T 17626.29, which is identical to the international standard;
IEC 61869-1:2007 is replaced by GB/T 20840.1-2010, which is modified in relation to the international standard;
IEC 61869-2:2012 is replaced by GB/T 20840.2-2014, which is modified in relation to the international standard;
IEC 61869-3:2011 is replaced by GB/T 20840.3-2013, which is modified in relation to the international standard;
——in order to adapt to the voltage conditions in China, in 5.3.601.2, the preferred a.c. voltage is changed from "100V~230V" to "110V, 220V";
——in order to adapt to national conditions of China, in Table 11 of 7.1.2, "gas dew point test" and "measurement of capacitance and dielectric dissipation factor" are adjusted from special tests to routine tests;
——in order to adapt to the climatic conditions in China, in 7.2.601.1, the ambient air temperature during the test is changed from "10℃~30℃" to "5℃~40℃";
——in order to adapt to national conditions of China, in Annex 6A, Figure 6A.2 is drawn according to "fr=50Hz, fs=4,000Hz" instead of "fr=60Hz, fs=4,800Hz".
The following editorial changes have been made in this part:
——IEC 60044-7:1999, IEC 60050-321:1986, IEC 60050-421:1990, IEC 61869 (all parts), IEC 61869-7 and IEEE C37.92-2005 in bibliography of IEC 61869-6:2016 are deleted.
This part was proposed by China Electrical Equipment Industrial Association.
This standard is under the jurisdiction of National Technical Committee on Instrument Transformers of Standardization Administration of China (SAC/TC 222).
Instrument transformers - Part 6: Additional general requirements for low-power instrument transformers
1 Scope
This part of GB/T 20840 covers additional general technical requirements for low-power instrument transformers (LPIT) used for a.c. applications having rated frequencies from 15Hz to 100Hz or used for d.c. applications. This product standard is based on GB/T 20840.1, in addition to the relevant product specific standard.
This part does not cover the specification for the digital output format of instrument transformers.
This part defines the errors in case of analogue or digital output. The other characteristics of the digital interface for instrument transformers are specified in GB/T 20840.9 as an application of the standards, which details layered substation communication architecture.
This part considers additional requirements concerning bandwidth. The accuracy requirements on harmonics and requirements for the anti-aliasing filter are given in Annex 6A.4.
The general block diagram of single-phase LPIT is given in Figure 601.
According to the technology, it is not absolutely necessary that all parts described in Figure 601 are included in the instrument transformer.
As an example, for low-power passive transformers (LPITs without active electronic components), the blocks are composed only with passive components and there is no power supply.
Figure 601 General block diagram of a single-phase LPIT
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
Clause 2 of GB/T 20840.1-2010 is applicable with the following additions:
GB/T 7826 Analysis techniques for system reliability - Procedure for failure mode and effects analysis (FMEA) (GB/T 7826-2012, IEC 60812:2006, IDT)
GB/T 17626.11 Electromagnetic compatibility - Testing and measurement techniques - Voltage dips, short interruptions and voltage variations immunity tests (GB/T 17626.11-2008, IEC 61000-4-11:2004, IDT)
GB/T 17626.29 Electromagnetic compatibility - Testing and measurement techniques - Voltage dips, short interruptions and voltage variations on d.c. input power port immunity tests (GB/T 17626.29-2006, IEC 61000-4-29:2000, IDT)
GB/T 20840.1-2010 Instrument transformers - Part 1: General requirements (IEC 61869-1:2007, MOD)
GB/T 20840.2-2014 Instrument transformers - Part 2: Additional requirements for current transformers (IEC 61869-2:2012, MOD)
GB/T 20840.3-2013 Instrument transformers - Part 3: Additional requirements for inductive voltage transformers (IEC 61869-3:2011, MOD)
IEC 60068-2-6:2007 Environmental testing - Part 2-6: Tests - Test Fc: Vibration (sinusoidal)
IEC 60255-27:2013 Measuring relays and protection equipment - Part 27: Product safety requirements
IEC 60603-7-1:2011 Connectors for electronic equipment - Part 7-1: Detail specification for 8-way, shielded, free and fixed connectors
IEC 60794-2:2002 Optical fibre cables – Part 2: Indoor cables - Sectional specification
IEC 60794-3:2014 Optical fibre cables – Part 3: Outdoor cables - Sectional specification
IEC 61000-4-1:2006 Electromagnetic compatibility (EMC) - Part 4-1: Testing and measurement techniques - Overview of IEC 61000-4 series
IEC 61000-4-2:2008 Electromagnetic compatibility (EMC) - Part 4-2: Testing and measurement techniques - Electrostatic discharge immunity test
IEC 61000-4-3:2006+IEC 61000-4-3:2006/AMD1:2007+IEC 61000-4-3:2006/AMD2:2010 Electromagnetic compatibility (EMC) - Part 4-3: Testing and measurement techniques - Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-4:2012 Electromagnetic compatibility (EMC) - Part 4-4: Testing and measurement techniques - Electrical fast transient/burst immunity test
IEC 61000-4-5:2014 Electromagnetic compatibility (EMC) - Part 4-5: Testing and measurement techniques - Surge immunity test
IEC 61000-4-6:2013 Electromagnetic compatibility (EMC) - Part 4-6: Testing and measurement techniques - Immunity to conducted disturbances, induced by radio-frequency fields
IEC 61000-4-7:2002+IEC 61000-4-7:2002/AMD1:2008 Electromagnetic compatibility (EMC) - Part 4-7: Testing and measurement techniques - General guide on harmonics and interharmonics measurements and instrumentation, for power supply systems and equipment connected thereto
IEC 61000-4-8:2009 Electromagnetic compatibility (EMC) - Part 4-8: Testing and measurement techniques - Power frequency magnetic field immunity test
IEC 61000-4-9:1993+IEC 61000-4-9:1993/AMD1:2000 Electromagnetic compatibility (EMC) - Part 4-9: Testing and measurement techniques - Section 9: Pulse magnetic field immunity test
IEC 61000-4-10:1993+IEC 61000-4-10:1993/AMD1:2000 Electromagnetic compatibility (EMC) - Part 4-10: Testing and measurement techniques - Section 10: Damped oscillatory magnetic field immunity test. Basic EMC Publication
IEC 61000-4-13:2002+IEC 61000-4-13:2002/AMD1:2009 Electromagnetic compatibility (EMC) - Testing and measurement techniques - Harmonics and interharmonics including mains signaling at a.c. power port, low frequency immunity test
IEC 61000-4-16:1998+IEC 61000-4-16:1998/AMD1:2001+IEC 61000-4-16:1998/AMD2:2009 Electromagnetic compatibility (EMC) - Part 4-16: Testing and measurement techniques - Test for immunity to conducted, common mode disturbances in the frequency range 0 Hz to 150 kHz
IEC 61000-4-18:2006+IEC 61000-4-18:2006/AMD1:2010 Electromagnetic compatibility (EMC) - Part 4-18: Testing and measurement techniques - Damped oscillatory wave immunity test
IEC 61025:2006 Fault tree analysis (FTA)
IEC 61076-2-101:2012 Connectors for electronic equipment - Product requirements - Part 2-101: Circular connectors - Detail specification for M12 connectors with screw-locking
IEC 61850-2:2003 Communication networks and systems in substations - Part 2: Glossary
IEC 61850-7-4:2010 Communication networks and systems for power utility automation - Part 7-4: Basic communication structure - Compatible logical node classes and data object classes
IEC/TR 61869-103:2012 Instrument Transformers - The use of instrument transformers for power quality measurement
IEC 62271-100:2008 High-voltage switchgear and controlgear - Part 100: Alternating current circuit-breakers
ISO/IEC/IEEE 21451-4:2010 Information technology - Smart transducer interface for sensors and actuators - Part 4: Mixed-mode communication protocols and Transducer Electronic Data Sheet (TEDS) formats
CISPR 11:2015 Industrial, scientific and medical equipment - Radio-frequency disturbance characteristics - Limits and methods of measurement
EN 50160:2010 Voltage characteristics of electricity supplied by public distribution systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 20840.1 and the following apply.
3.1 General definitions
3.1.601
low-power instrument transformer
LPIT
arrangement, consisting of one or more current or voltage transformer(s) which may be connected to transmitting systems and secondary converters, all intended to transmit a low power analogue or digital output signal to measuring instruments, meters and protective or control devices or similar apparatus
Example: An arrangement consisting of three current sensors, three voltage sensors connected to one merging unit delivering one digital output is considered an LPIT.
Note 1: LPITs are commonly called non-conventional instrument transformers (NCIT).
Note 2: The output power produced by these devices is typically lower than or equal to 1VA.
3.1.602
low-power current transformer
LPCT
low-power instrument transformer for current measurement
3.1.603
low-power voltage transformer
LPVT
low-power instrument transformer for voltage measurement
3.1.604
measuring LPIT
LPIT intended to transmit an output signal to measuring instruments and meters
3.1.605
protective LPIT
LPIT intended to transmit an output signal to protective and control devices
3.1.606
multipurpose LPIT
LPIT intended for both measurement and protection applications
3.1.607
electronic LPIT
LPIT that includes active components
3.1.608
passive LPIT
LPIT that includes only passive components
3.1.609
input signal
signal corresponding to the current or to the voltage applied between the primary terminals of the LPIT
3.1.610
primary sensor
electrical, optical or other device intended to provide information about the input signal in order to transmit it to the secondary converter, either directly or by means of a primary converter
3.1.611
primary converter
electrical, optical or other device that converts the signal coming from one or more primary sensors into a signal suitable for the transmitting system
3.1.612
primary power supply
auxiliary power supply to the primary converter and/or primary sensor
Note: May be combined with secondary power supply (see 3.1.620).
3.1.613
transmitting system
short- or long-distance coupling arrangement between primary and secondary parts intended to transmit the signal
Note: Depending on the technology used, the transmitting system may also be used for power transmission.
3.1.614
secondary converter
arrangement that converts the signal transmitted through the transmitting system into a signal proportional to the input signal, to supply measuring instruments, meters and protective or control devices
Note: For analogue output, the secondary converter directly supplies measuring instruments, meters and protective or control devices. For digital output, the secondary converter is connected to a merging unit before supplying the secondary equipment.
3.1.615
logical device merging unit
logical device (in the meaning of IEC 61850-7-4:2010) to do the time-coherent combination of logical nodes current transformer (TCTR) and/or logical nodes voltage transformer (TVTR) for building a standard digital output
3.1.616
merging unit, MU
physical device (IED according to IEC 61850-2:2003) in which a logical device merging unit is implemented
Note 1: The merging unit may be part of one of the instrument transformers in the field or may be a separate unit, for example, in the control room.
Note 2: The inputs of the merging unit may be proprietary or standardized.
3.1.617
stand-alone merging unit, SAMU
merging unit with standardized inputs (analogue or digital)
Example 1: SAMU may be used with instrument transformers for retrofit purposes.
Example 2: Digital input of the stand-alone merging unit may be specified according to former GB/T 20840.8-2007 digital output or according to GB/T 20840.9. This possibility ensures the compatibility between GB/T 20840.8-2007 and the new GB/T 20840 series.
3.1.618
merging unit clock input
electrical or optical input of the merging unit that may be used to synchronize several merging units if required
3.1.619
merging unit power supply
auxiliary power supply of the merging unit
Note: A merging unit power supply may be combined with the secondary power supply (see 3.1.620).
3.1.620
secondary power supply
auxiliary power supply of the secondary converter
Note: A secondary power supply may be combined with primary power supply (see 3.1.612) or a power supply of other instrument transformers.
Contents of GB/T 20840.6-2017
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Normal and special service conditions
5 Ratings
6 Design and construction
7 Tests
601 Information to be given with enquiries, tenders and orders
Annex 6A (Normative) LPIT frequency response and accuracy requirements for harmonics
Annex 6B (Informative) Transient performances of low-power voltage transformers
Annex 6C (Informative) Transient performances of low-power current transformers
Annex 6D (Informative) Test circuits
Annex 6E (Informative) Graph explaining the accuracy requirements for multi-purpose low-power current transformer
Bibliography
