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GB 1094.1-2013: [GB/T 1094.1-2013, Including 2017XG1] Power transformers -- Part 1: General
GB 1094.1-2013
GB
NATIONAL STANDARD OF THE
PEOPLE?€?S REPUBLIC OF CHINA
ICS 29.180
K 41
Replacing GB 1094.1-1996
Power transformers - Part 1: General
(IEC 60076-1:2011, MOD)
Transferred to a recommended standard according to the Standardization
Administration?€?s announcement No. 7, 2017
[Including 2017XG1]
ISSUED ON: DECEMBER 17, 2013
IMPLEMENTED ON: DECEMBER 14, 2014
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People?€?s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 7
3 Terms and definitions ... 8
4 Service conditions ... 26
5 Rating and general requirements ... 29
6 Requirements for transformers having a tapped winding ... 36
7 Connection and connection symbol ... 44
8 Rating plates ... 50
9 Safety, environmental and other requirements ... 53
10 Tolerances ... 55
11 Tests ... 57
12 Electromagnetic compatibility (EMC) ... 69
13 High frequency switching transients ... 69
Annex A (Informative) Technical differences between this Part and IEC 60076-1:2011
and their causes ... 70
Annex B (Informative) Vacuum deflection test for liquid immersed transformers and
pressure deflection test for liquid-immersed type transformers in IEC 60076-1:201173
Annex C (Informative) Examples of three-phase transformer connections ... 76
Annex D (Informative) Check list of information to be provided with enquiry and order
... 79
Annex E (Informative) Examples of specifications for transformers with tappings .. 85
Annex F (Informative) Specification of short-circuit impedance by boundaries ... 90
Annex G (Normative) Temperature correction of load loss ... 91
Annex H (Informative) Facilities for future fitting of condition monitoring systems to
transformers ... 93
Annex I (Informative) Environmental and safety considerations ... 95
Bibliography ... 97
No. 1 Amendment [2017XG1] ... 100
Foreword
Clause 2, Clause 3, 11.2 ~ 11.12, Clause 12, Clause 13, Annex A ~ Annex F, Annex
H, and Annex I of this Part are recommended, and the rest are mandatory.
GB 1094 Power transformers currently includes the following parts:
-- Part 1: General;
-- Part 2: Temperature rise for liquid-immersed transformers;
-- Part 3: Insulation levels, dielectric tests and external clearances in air;
-- Part 4: Guide to the lightning impulse and switching impulse testing - Power
transformers and reactors;
-- Part 5: Ability to withstand short circuit;
-- Part 6: Reactors;
-- Part 7: Loading guide for oil-immersed power transformers;
-- Part 10: Determination of sound levels;
-- Part 10.1: Determination of sound levels - Application guide;
-- Part 11: Dry-type transformers;
-- Part 12: Loading guide for dry-type power transformers;
-- Part 14: Liquid-immersed power transformer using high-temperature insulation
materials;
-- Part 16: Transformers for wind turbine applications.
This Part is Part 1 of GB 1094.
This Part is drafted in accordance with the rules given in GB/T 1.1-2009.
This Part replaces GB 1094.1-1996, Power transformers - Part 1: General. Compared
with GB 1094.1-1996, the main technical changes are as follows:
-- Add the definition of harmonic content;
-- Add a subclause on transport;
-- Add functional method of specification;
-- Add connection symbols for single phase transformers;
-- Add safety and environmental requirements;
-- Add requirements for liquid preservation systems;
-- Add a clause on DC currents in neutral circuits;
-- Adjust the test items;
-- Add contents such as leak testing with pressure for liquid-immersed type
transformers (tightness test), vacuum deflection test for liquid immersed
transformers, pressure deflection test for liquid-immersed type transformers, and
vacuum tightness test on site for liquid-immersed type transformers;
-- Add informative annexes on facilities for condition monitoring to transformers
and environmental and safety considerations.
This Part uses the re-drafting method to modify IEC 60076-1:2011 Power transformers
- Part 1: General.
There are technical differences between this Part and IEC 60076-1:2011. The terms
which are involved in these differences have been marked by vertical single lines (|) on
the outer page margins; Annex A gives a list of corresponding technical differences and
their causes.
This Part also makes the following editorial changes:
-- Change ?€?Ei?€? and ?€?Ii?€? in the key of 3.13.3 in IEC 60076-2011 to ?€?E2i?€? and ?€?I2i?€?
respectively;
-- Combine Figure 1a), Figure 1b) and Figure 1c) in IEC 60076-1:2011 into one
figure;
-- Remove the content of ?€?Note?€? of 7.1.2 in IEC 60076-1:2011;
-- Make the example under 7.2.4 in IEC 60076-1:2011 the content of 7.2.5;
-- Adjust the layout of Table 1 in IEC 60076-1:2011;
-- Modify the tap-position in Table B.2 and Table B.3 in IEC 60076-1: 2011;
-- Add the informative Annex A, where the technical differences between this Part
and IEC 60076-1:2011 and the causes are listed;
-- Add the informative Annex B, where the contents ?€? vacuum deflection test for
liquid immersed transformers and pressure deflection test for liquid-immersed
type transformers ?€? not adopted from IEC 60076-1:2011, are listed;
Power transformers - Part 1: General
1 Scope
This part of GB 1094 applies to three-phase and single-phase power transformers
(including auto-transformers) with the exception of certain categories of small and
special transformers such as:
-- single-phase transformers with rated power less than 1 kVA and three-phase
transformers less than 5 kVA;
-- transformers, which have no windings with rated voltage higher than 1 000 V;
-- transformers;
-- traction transformers mounted on rolling stock;
-- starting transformers;
-- testing transformers;
-- welding transformers;
-- explosion-proof and mining transformers;
-- transformers for deep water (submerged) applications.
When standards do not exist for such categories of transformers (in particular
transformer having no winding exceeding 1000 V for industrial applications), this Part
may still be applicable either as a whole or in part.
This standard does not address the requirements that would make a transformer suitable
for mounting in a position accessible to the general public.
For those categories of power transformers and reactors which have their own standards,
this Part is applicable only to the extent in which it is specifically called up by cross-
reference in the other product standard. Such product (standards) exist for:
-- reactors in general (GB/T 1094.6);
-- dry-type transformers (GB 1094.11);
-- self-protected transformers (IEC 60076-13);
-- gas-filled power transformers (IEC 60076-15);
-- corrosion protection, according to the kind of installation and the installation
environment (see 4.2), the purchaser shall choose classes of protection in ISO
12944 or by agreement between purchaser and manufacturer;
-- load rejection conditions for generator transformers more severe than those given
in 5.3 above;
-- commissioning at extremely low temperature;
-- special wiring method;
-- special installation location and layout method;
-- installation in public places;
-- special grounding method of neutral points.
Transformer specification for operation under such abnormal conditions shall be subject
to agreement between the supplier and purchaser.
Supplementary requirements, within defined limits, for the rating and testing of
transformers designed for other than normal service conditions listed in Clause 4, such
as high temperature of cooling air or altitude above 1 000 m are given in GB 1094.2.
5.6 Highest voltage for equipment Um and dielectric tests levels
For line terminals, unless otherwise specified by the purchaser, Um shall be taken to be
equal to or slightly larger than the rated voltage of each winding.
For transformer windings with a highest voltage for equipment greater than 72.5 kV,
the purchaser shall specify whether any neutral terminals for that winding are to be
directly earthed in service or not, and if not, the Um for the neutral terminals shall be
specified by the purchaser.
Unless otherwise specified by the purchaser, dielectric test levels shall be taken to be
the lowest applicable value corresponding to Um, given in GB 1094.3.
5.7 Additional information required for enquiry
5.7.1 Transformer classification
The kind of transformer, for example, separate winding transformer, auto-transformer
or series transformer shall be specified by the user.
5.7.2 Winding connection and number of phases
The required winding connection shall be specified by the user in accordance with the
requirements given in Clause 7.
Following the application of the vacuum for the site operation, the distance from the
reference point to the tank wall shall be measured again. The deflection under vacuum
is the difference between this measurement and the previous measurement.
The vacuum shall then be released and another measurement of the distance from the
reference point to the tank wall shall be taken. The permanent deflection is the
difference between this measurement and the first measurement.
Alternative equivalent methods of measurement may be used and additional
measurements on the opposite side of the transformer may be required to compensate
for tank movement during the test.
Normally, the expected deflection under vacuum and the permanent deflection shall be
calculated and declared by the manufacturer before the test.
If the expected value is exceeded, the test shall be repeated to determine whether the
tank size is stable. If unstable, remedial measures shall be taken, such as additional
reinforcement of the tank.
Note: For the relevant provisions on vacuum deflection test for liquid immersed
transformers in IEC 60076-1:2011, refer to Annex B.
11.10 Pressure deflection test for liquid-immersed type transformers
Where specified, the deflection of the tank when pressure is applied and the permanent
deflection of the tank when the pressure is released shall be measured. For tanks that
are specifically designed to be flexible for liquid expansion (corrugated), this test is not
applicable.
The test shall be carried out on the transformer when it is complete in all relevant
respects and filled with liquid. It shall be carried out on all separate compartments that
contain liquid.
Unless otherwise specified, the test pressure in the tank shall be 35 kPa over the normal
operating pressure. If the transformer is fitted with pressure relief devices, the pressure,
applied during this test shall exceed the pressure required to operate the pressure relief
device by at least 10 kPa. Pressure relief devices shall therefore need to be blanked off
during this test.
Note 1: The specified overpressure may conveniently be applied by adjusting the height
of a liquid column (for example by lifting a separate conservator attached to a
crane).
Before the application of pressure, the liquid level in the tank shall be at a normal height
and a suitable reference point shall be established. The reference point shall be
independent of the transformer and fixed on a structural member or floor of the site.
The reference point shall be as close as possible to the point where the maximum
deformation is expected to occur under pressure, and the influence of the deformation
amount shall also be taken into consideration. The distance from the reference point to
the tank wall shall be measured and recorded.
Following the application of the additional pressure, the distance from the reference
point to the tank wall shall be measured again. The difference between the two
measured distances is the pressure deformation.
Alternative equivalent methods of measurement may be used and additional
measurements on the opposite side of the transformer may be required to compensate
for tank movement during the test.
Then the pressure shall be reduced to the initial value and the third distance
measurement performed. The difference between this measurement and the first
measurement is the permanent deflection.
Normally, the expected deflection under vacuum and the permanent deflection shall be
calculated and declared by the manufacturer before the test.
If the limit value is exceeded, the test shall be repeated to determine whether the tank
size is stable. If unstable, remedial measures shall be taken, such as additional
reinforcement of the tank.
Note 2: For the relevant provisions on pressure deflection test for liquid-immersed type
transformers specified in IEC 60076-1:2011, refer to Annex B.
11.11 Vacuum tightness test on site for liquid-immersed type transformers
This test is applicable to transformers designed to be vacuum filled in their own tanks
on site and transported without liquid. Following erection on-site but before liquid
filling, the ability of a transformer that requires the application of vacuum for filling or
other site operations to hold a vacuum without admitting air shall be demonstrated as
follows:
A vacuum to the highest level required by the site operation shall be applied for a period
of two hours or until a stable vacuum level is obtained. The vacuum pump shall then be
stopped. Keep it for 10 minutes, then record the first vacuum pressure value, and then
measure it again 30 minutes later. The pressure increase shall be less than 200 Pa/h.
11.12 Check of core and frame insulation
This test shall be carried out on all liquid-immersed type transformers which
incorporate insulation separating core and frame and/or frame and tank.
For transformers where the core and frame earth connections are not accessible when
the transformer is liquid filled, the insulation shall be tested at 500 V DC for 1 min
without breakdown before the active part is installed in the tank.