STANDARD SPECIFICATIONS AND TECHNICAL PARAMETERS FOR TRANSFORMERS AND REACTORS (66 kV & ABOVE VOLTAGE CLASS) GOVERNMENT OF INDIA MINISTRY OF POWER CENTRAL ELECTRICITY AUTHORITY APRIL 2021
STANDARD SPECIFICATIONS AND TECHNICAL PARAMETERS FOR TRANSFORMERS AND REACTORS (66 kV & ABOVE VOLTAGE CLASS)
Apr 05, 2023
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CENTRAL ELECTRICITY AUTHORITY
Government of India
Ministry of Power
Central Electricity Authority
Power System Engineering & Technology Development Division 3rd Floor, Sewa Bhawan, R.K. Puram, New Delhi – 66,
, As per attached List
: Amendment No. 1 to “Standard Specifications and technical Parameters for Transformers and Reactors (66 kV & above voltage class)”-reg.
As you are aware that “Standard Specifications and technical Parameters for Transformers and Reactors (66 kV & above voltage class)” duly approved by Hon`ble Minister of Power and New and Renewable Energy was circulated by this office vide letter dated 29.04.2021 to all the concerned utilities. Further, the document also empowers the committee under Chairmanship of Member (Power System) with representation from stakeholders (IEEMA, EPTA, CPRI, POWERGRID, NTPC, NHPC, Two STUs) as members and CE (PSETD) as Member Secretary of the committee to carry out updation of the document every two years and any amendment, if there is an urgency. Clause No. 7 of Chapter 2 of the above mentioned document mandates the requirement of Dynamic Short Circuit Test for Transformers.
Representation has been received from multiple organizations citing that presently none of the Transformer manufacturer has got their design of 765 kV class and 500 MVA, 400 kV class transformer tested for dynamic short circuit withstand capability and process of getting the design tested would take approximately 15-18 months and only after successful testing subsequent units can be manufactured which will further take few months depending upon availability of material and capacity in the works. Manufacturers are in no position to deliver the transformer of tested design within next 24 Months. This scenario could delay the completion schedule of many transmission projects, specially associated with the evacuation of renewable generation.
To deliberate the issue of DSC requirement for the above mentioned transformers, a meeting of the committee under Chairmanship of Member (Power System) was held on 28.08.2021. After detailed deliberations
Page 1 of 15
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following amendment in clause 7 of Chapter 2 of “Standard Specification and Technical Parameters for Transformers and Reactors (66 kV and above)” was finalized:
Existing Provision Amended Provision
7.0 DYNAMIC SHORT CIRCUIT TEST REQUIREMENT AND VALIDITY The transformer, the design of which is similar to the offered transformer, should have been successfully tested for short circuit withstand capability as per IS 2026 Part-5 in line with the requirement of CEA (Technical Standards for Construction of Electrical Plants and Electric Lines) Regulations. The criteria for similar transformer is specified in Annexure-J. The relevant Test Report/certificate shall be enclosed along with bid. Further, design review of offered transformer shall be carried out based on the design of reference transformer, which has already been subjected to Short circuit tests in lieu of repetition of Short circuit tests. In case, manufacturer has not conducted short circuit test earlier, the same shall be carried out on offered transformer.
A format (forms part of Annexure-J) filled with data of a typical sample case has been prepared for reference and guidance of utility to compare a Short Circuit tested transformer with the offered transformer in order to verify the similarity criteria as per Annexure J.
7.0 DYNAMIC SHORT CIRCUIT TEST REQUIREMENT AND VALIDITY The transformer the design of which is similar to the offered transformer, should have been successfully tested for short circuit withstand capability as per IS 2026 Part-5 within last 5 years. The criteria for similar transformer is specified in Annexure-J. The relevant Test Report/certificate shall be enclosed along with bid. Further, design review of offered transformer shall be carried out based on the design of reference transformer, which has already been subjected to Short circuit tests in lieu of repetition of Short circuit tests. In case, manufacturer has not conducted short circuit test earlier, the same shall be carried out on offered transformer.
However, considering the fact that dynamic short circuit tested design is not available for 765 kV voltage class Auto Transformer & 500 MVA, 400 kV voltage class Auto Transformer and testing of these transformers would require some more time, the above requirement of Dynamic short circuit (DSC) withstand test for these transformers shall be applicable for the projects for which bid invitation date is after 31st August 2023. For these transformers, theoretical evaluation of the ability to withstand the dynamic effects of short circuit, based on calculation and consideration of the design characteristics and manufacturing practices, shall be carried out as per IS 2026-5/IEC 60076-5.
A format (forms part of Annexure-J) filled with data of a typical sample case
Page 2 of 15
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Textbox
has been prepared for reference and guidance of utility to compare a Short Circuit tested transformer with the offered transformer in order to verify the similarity criteria as per Annexure J
Further, queries have been received in this office on applicability of subject document for the projects awarded before issuance of the document. In this regard, it is clarified that the subject document was issued in April 2021 and shall be applicable for projects which were awarded after the issuance of the document. Similarly, another document “Standard Technical Specification of transformers for Solar Park Pooling Station” was issued in June 2021 and shall be applicable for projects, which were awarded after the issuance of the document.
/ Regards
( / Akshay Dubey) % / Deputy Director
Page 3 of 15
New Delhi - 110001
ft-gi,iai-dq +rq qrk rr{r
=r$ ffi-rtooor re|€ : 237't 027 1 I 237 1 1 31 6
Fax :23721487 E-mail : [email protected]
Secretary Govemment of lndia
The complexity of lndian Power System has increased manifold with formation of one of the largest single synchronous grid in the world. ln present scenario, the major assets of a power system would play an important role not only in terms of investment but also in terms of availability and reliability of the system.Transformers and reactors as compensating device are the vital & essential assets in Power delivery system. Reliability and availability of such assets play important role in uninterrupted power supply and smooth operation of a power system.
The "Standard specifications and technical parameters for transformer and reactors (66 kV and above voltage class)" is a much awaited technical document thoroughly updated in line with national and international best practices for the benefit of all stakeholders involved. The manual has specifically been prepared keeping in view the domestic as well as international requirement by incorporation of best design practices, quality control and testing requirements.
The uniform practice across the utilities in the country would place all manufacturers at a level playing field and benefit indigenous manufacturers, reinforcing the vision of Aatma-Nirbhar Bharat. lt would provide a further fillip to 'Make in lndia' initiative. This initiative would simplify the procurement process, bringing in faster delivery, overall efficiency, quality and productivity in the entire value chain of transformer / reactor procurement & operation.
I thank members of the Committee and all contributors including officers of Central Electricity Authority (CEA) for their sincere effo(s & invaluable contribution in bringing out this document. Since the consultation with large number of stake holders has already been held, I would urge for adoption of this standard specifications by the utilities and manufacturers across the country in true spirit in order to achieve the ultimate objective of cost effective uninterrupted (24x7) qualily power to all consumers and smooth operation of the Power System.
Feedback from the users for improvement of the document is welcome
(Alok Kumar)
$tR, w.u.u. {rFfq
& REACTORS
3.0 Guaranteed and other technical particulars II-1
4.0 Standard ratings of transformer and reactor II-2
5.0 Performance II-2
validity
II-7
9.0 Design review II-8
10.0 Service condition II-8
11.0 Construction details II-9
13.0 Insulating oil II-26
unit into service for replacement of one of
the single phase transformer/reactor units
of a three phase bank
II-27
II-30
arrangement
II-32
Transformer)
II-32
20.0 Valves II-40
21.0 Cabling II-43
23.0 SCADA integration II-53
Cabinet/Individual Marshalling Box/
control and power circuit
current transformer
30.0 Drawings/documents/calculations II-62
transformer/reactor
II-69
reactor of different make
4.0 Calculation of losses, weight of core and
current density of winding conductor
III-5
3.0 Quality assurance documents IV-6
4.0 Quality during inspection & testing
(including virtual inspection) and inspection
certificates
IV-7
5.0 Inspection and testing
5.1 Factory test 5.2 Stage inspection 5.3 Type tests on fittings
IV-14
works
IV-17
Transformer/ Reactor at site in presence of
manufacturer’s and purchaser’s
representative
V-2
at site
7.0 Drying of wet winding of transformer/
reactor by application of vacuum, Dry
nitrogen gas filling and heating
V-14
filter machine
11.0 Inspection and testing at site V-22
12.0 Pre-Commissioning checks and tests for
transformers and reactors
16.0 Flow chart for erection activities
V-31
MANAGEMENT
2.1 Winding Resistance Measurement VI-3
2.2 Voltage Ratio Test (only for transformers)
VI-5
2.6 Capacitance and Tan delta of Windings VI-10
2.7 Capacitance and Tan delta of Bushings VI-12
2.8 Short Circuit Impedance (only for transformers)
VI-14
2.9 Operational checks and Inspection of OLTC (only for transformers)
VI-14
2.11 Dissolved Gas Analysis (DGA) and Interpretation
VI-16
VI-34
2.15 Moisture Measurement & Control VI-37
2.16 Thermo Vision Scanning VI-37
3.0 Remnant Life measurement of Paper
insulation
VI-38
transformer/reactor and other maintenance
6.0 Recommended, as-needed, and optional
maintenance tests as per IEEE Std.
C57.152-2013
VI-41
Reactor
VI-43
Reactors
VI-46
Annexure–B: Technical Parameters of Bushing Current Transformers & Neutral
Current Transformers
Annexure–C: Guaranteed & Other Technical Particulars
Annexure–D: Test Plan and Procedures
Annexure–E: Standard Manufacturing Quality Plan
Annexure–F: Typical Example for Calculation of Flux Density, Core Quantity, No-
Load Loss and Weight of Copper
Annexure–G: Basic Manufacturing Facility & Manufacturing Environment
Annexure–H: List of Drawings/Documents to be submitted by the manufacturer
Annexure–I: Scope of Design Review
Annexure–J: Criteria for selection of similar reference transformer for dynamic
short circuit withstand test
Annexure–K: Painting Procedure
Annexure–M: Standard Dimensions for Lower Portion of Condenser Bushings
Annexure–N: Connection Arrangement for Bringing Spare Unit into Service for
Replacement of One of the Single Phase Transformer/Reactor Units
of a Three Phase Bank
Annexure-O: Typical Arrangement for Neutral Formation for Single Phase Units
Annexure–P: Physical Interchangeability of Transformers and Reactors of
Different Makes
Annexure–Q:
Standard GA Drawings and Limits of Supply Between Suppliers of Transformer and Dry-Type Cable/GIS Termination for Hydro Plants
Annexure–R: 1100 V Grade Power and Control Cable
Annexure–S: Specification for Oil Storage Tank
Annexure–T: Specification for BDV Test Set & Portable DGA Kit
Annexure–U: Specification for On-line Insulating Oil Drying System (Cartridge type)
Annexure–V: Specification for Oil Sampling Bottles & Oil Syringe
Annexure–W: List of Codes/Standards/Regulations/Publications
Chapter-1
Introduction
The phenomenal growth of Indian Power transmission system has resulted
in the formation of One Nation One Grid, one of the largest single
synchronous Grids in the world. The transmission system establishes the
vital link between the generating source and the distribution system
connected to the ultimate consumer. A Robust, Reliable and Optimally
Planned transmission network would facilitate in achieving ultimate
objective of cost effective delivery of power and providing 24x7 Quality
Power for All consumers at affordable rate. In coming years, huge
generation capacity addition including large scale integration of generation
from renewable sources, expansion of electricity market and exchange of
Power between India & neighboring countries would further require
commensurate expansion & strengthening of the associated Transmission
& Distribution network. The complexity of Indian Power System has
increased manifold over the years. With operation of multiple agencies
(State Utilities, Central Utilities, and Private players) in power sector, high
availability & reliable operation assumes tremendous importance in
present scenario. In such a scenario, the major assets of a power system
would play an important role not only in terms of investment but also in
terms of availability and reliability of the system.
The transformer and reactor are vital and expensive assets in a power
system. The increase in demand for energy will require enhancement in
transformation capacity as well as reactive compensation requirement.
Reliability and availability of such important assets plays an important role
in the smooth operation of a power system. Emphasis needs to be laid on
improved design, quality control during manufacturing, use of right
components/accessories, maintenance and safety during operation of
such vital assets. Generally, due to poor quality of raw material,
workmanship, and manufacturing techniques or due to normal and
abnormal stresses of the system during the operation (like frequent system
faults, over loading, environmental effect, unexpected continuous
operating voltage and over voltage stresses), and poor maintenance
practice, transformers/reactors fail much before their expected life span
(expected life span of about 35 years). The failure of such vital equipment
can have significant economic impact due to high cost, long lead time in
procurement, manufacturing and installation. Long repair time is a matter
of concern in many cases of failure of transformer/reactor. Restoration of
transformer/reactor takes about 3 to 6 months after major repair at
manufacturer’s works depending on the type of repair and procurement of
Chapter-1 : Introduction Page I-2
a new one requires 6-10 months depending on the voltage class of
transformer/reactor.
There is no uniform practice across the utilities in the Country as far as
the technical specification of transformer/reactor is concerned. At present,
same rating/class of transformers/reactors are being designed differently
even for the same user. Even for same specifications, manufacturer review
design for successive tenders considering prevailing market condition. This
results in unnecessary increase in design & manufacturing cycle time,
cost, human efforts & inventories. In view of above there was need to
address this issue and develop a standard/common design & engineering
specification for transformer & reactor incorporating the best practices of
various utilities, latest technological development and future trends, which
would be followed by utilities & manufacturers across the Country. The
objective of this initiative is to formulate a standard document bringing out
critical technical parameters of transformer and reactors which affects the
quality, reliability, efficiency and cost of such assets.
This standardization process shall have following advantages:
• The procurement process will be simplified and delivery time would be
reduced resulting in early completion of project
• Due to standard design, frequent design reviews can be avoided
• Standard ratings and standard civil foundation block would facilitate
interchangeability of different make of transformer / reactor
• Standard fittings and accessories
• Lesser requirement of inventories
Keeping in view above objective, Ministry of Power vide order no.
10/24/2016-PG dated 20.08.16, had constituted a committee under the
Chairmanship of Member (Power System), CEA, with the following
composition:
2. CMD, PGCIL
The Terms of Reference of the Committee are as under:
Chapter-1 : Introduction Page I-3
a) To adopt country wide standard designs of Power transformers for
each class ratings and performance parameter wise (including losses);
b) To reduce lead time, human efforts & errors during the transformer
procurement process by adopting standard losses and detailed
guaranteed technical particular (GTP) format;
c) To adopt specifications and application guides for various fittings and
accessories for the selection and maintenance of transformer
components;
d) To follow the Guidelines for preparation and checking of standard
contract drawings preferred cooler and OLTC control schemes;
e) To adopt standard Manufacturing Quality Plan (MQP) for
manufacturing, testing and packing of transformers to define and
ensure quality for reliability;
f) To enhance the overall efficiency, quality and productivity in the entire
value chain of transformer procurement and operation;
g) To achieve interchangeability of transformers of different make,
procured by different utilities – by standardizing the losses, lay out
and foundation plan of transformers; and
h) To achieve shorter deliveries of power transformers for timely and
speedier completion of projects.
Several rounds of meetings were held in CEA with stake holders, utilities
and manufacturers of transformer, reactor & their accessories for
standardization of Technical Specification so that both utilities and
manufacturers across the Country are benefitted and follow a uniform
practice. Although the terms of reference was focused exclusively for
transformer, but the standardization process has been extended to
cover the specification for the reactor of 220kV and above voltage
system as well.
transformers/reactors of 66 kV and above voltage class. The
document does not cover transformers suitable for Static Var
Compensator (SVC), Static Compensator (STATCOM), traction
transformers, welding transformers, testing transformers, mining
transformers, furnace transformers and inverter transformer for
Renewable generators.
manufacturing, transportation, erection, testing, commissioning and
condition monitoring of transformer/reactor. The commercial
aspects, contractual terms, scope of works for OEM/contractor etc.
may be defined by the utility as per its requirement and practice.
Chapter-1 : Introduction Page I-4
Some important points considered while preparing this document are as
under:
1. The purpose of this document is: (a) to standardize the ratings; (b)
bring uniformity in the design by fixing major technical parameters
including maximum permissible losses, eliminating the need for
capitalisation of losses; (c) facilitate physical inter-changeability of
different makes by standardizing the common mounting
arrangement/foundation plan; (d) improve manufacturing facility,
reliability & quality of supply of Transformer/Reactor from all
manufacturers; (e) achieve cost effective production & faster delivery;
and (f) adoption of Condition Based Maintenance (CBM) practices
across the utilities in the country to assess the health of assets.
2. Attempt has been made to standardize and restrict the number of
ratings of Power Transformers and Reactors at different voltage levels
so that the manufacturers shall have to design and manufacturer
fewer ratings resulting in requirement of less inventory of
components and faster delivery. In the process the focus will be on
quality of production which will be in overall interest of utilities,
manufacturers and the system.
Transformers and reactors have been standardized based on general
practice and most commonly used ratings in India.
POWER/ AUTO TRANSFORMERS:
1. 500 MVA (765/√3)/(400/√3)/33 kV Single Phase Auto
Transformer
Transformer
Three Phase Auto Transformer
Transformer
5. 105 MVA (400/√3)/(220/√3)/33 kV *(400/√3)/(230/√3)/33 kV
Single Phase Auto Transformer
Chapter-1 : Introduction Page I-5
Three Phase Auto
*400/110/33 kV
*220/110 kV
*220/110 kV
Three Phase Power Transformer
11. 100MVA 220/33 kV
Three Phase Power Transformer
Three Phase Power Transformer
Three Phase Power Transformer
Transformer
Transformer
Transformer
Sr. No. MVA Rating Line Voltage Rating Phase Type
1. 315 MVA Generation Voltage/(800/√3)kV Single GT
2. 265 MVA Generation Voltage/(800/√3)kV Single GT
3. 315 MVA Generation Voltage/(420/√3)kV
420(765/3) kV
Tran
sfor
mer
Tran
sfor
mer
1. 110 MVAR 765/3 kV Single Phase
Chapter-1 : Introduction Page I-6
3. 125 MVAR 420 kV Three Phase
4. 80 MVAR 420 kV Three Phase
5. 63 MVAR 420 kV Three Phase
6. 50 MVAR 420 kV Three Phase
7. 50 MVAR 245 kV Three Phase
8. 25 MVAR 245kV Three Phase
Note: Primary voltage rating for Generator Transformers (GTs) could not be
standardized as it depends on generator parameters and system
requirement. The MVA ratings of GTs for thermal plants have been
standardized for different voltage class. The MVA rating for GTs for Hydro
plant may be decided by the respective utility. Although some ratings of
Generator Transformers (GTs) could not be included due to certain technical
limitations, the utility may take the help of this document for such ratings of
GTs as far as possible.
In view of objectives and benefits highlighted in following paragraphs,
utilities are advised to procure transformers and reactors of these
ratings only as far as possible. The transformers/reactors of other
ratings should be procured only under special circumstances, for
example to match with the rating of existing transformer and for
parallel operation.
4. The fixation of maximum permissible loss values for transformers
(No-load loss, Load loss, I2R loss and auxiliary loss) and reactors (I2R
loss and total loss) has been done in consultation with utilities and
manufacturers. The method of calculation of losses has been given
along with a typical example for verifying the guaranteed values and
for measurement at manufacturer works so that all utilities across
the country get transformer and reactor of similar quality and
efficiency. Manufacturer shall…
Government of India
Ministry of Power
Central Electricity Authority
Power System Engineering & Technology Development Division 3rd Floor, Sewa Bhawan, R.K. Puram, New Delhi – 66,
, As per attached List
: Amendment No. 1 to “Standard Specifications and technical Parameters for Transformers and Reactors (66 kV & above voltage class)”-reg.
As you are aware that “Standard Specifications and technical Parameters for Transformers and Reactors (66 kV & above voltage class)” duly approved by Hon`ble Minister of Power and New and Renewable Energy was circulated by this office vide letter dated 29.04.2021 to all the concerned utilities. Further, the document also empowers the committee under Chairmanship of Member (Power System) with representation from stakeholders (IEEMA, EPTA, CPRI, POWERGRID, NTPC, NHPC, Two STUs) as members and CE (PSETD) as Member Secretary of the committee to carry out updation of the document every two years and any amendment, if there is an urgency. Clause No. 7 of Chapter 2 of the above mentioned document mandates the requirement of Dynamic Short Circuit Test for Transformers.
Representation has been received from multiple organizations citing that presently none of the Transformer manufacturer has got their design of 765 kV class and 500 MVA, 400 kV class transformer tested for dynamic short circuit withstand capability and process of getting the design tested would take approximately 15-18 months and only after successful testing subsequent units can be manufactured which will further take few months depending upon availability of material and capacity in the works. Manufacturers are in no position to deliver the transformer of tested design within next 24 Months. This scenario could delay the completion schedule of many transmission projects, specially associated with the evacuation of renewable generation.
To deliberate the issue of DSC requirement for the above mentioned transformers, a meeting of the committee under Chairmanship of Member (Power System) was held on 28.08.2021. After detailed deliberations
Page 1 of 15
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Textbox
following amendment in clause 7 of Chapter 2 of “Standard Specification and Technical Parameters for Transformers and Reactors (66 kV and above)” was finalized:
Existing Provision Amended Provision
7.0 DYNAMIC SHORT CIRCUIT TEST REQUIREMENT AND VALIDITY The transformer, the design of which is similar to the offered transformer, should have been successfully tested for short circuit withstand capability as per IS 2026 Part-5 in line with the requirement of CEA (Technical Standards for Construction of Electrical Plants and Electric Lines) Regulations. The criteria for similar transformer is specified in Annexure-J. The relevant Test Report/certificate shall be enclosed along with bid. Further, design review of offered transformer shall be carried out based on the design of reference transformer, which has already been subjected to Short circuit tests in lieu of repetition of Short circuit tests. In case, manufacturer has not conducted short circuit test earlier, the same shall be carried out on offered transformer.
A format (forms part of Annexure-J) filled with data of a typical sample case has been prepared for reference and guidance of utility to compare a Short Circuit tested transformer with the offered transformer in order to verify the similarity criteria as per Annexure J.
7.0 DYNAMIC SHORT CIRCUIT TEST REQUIREMENT AND VALIDITY The transformer the design of which is similar to the offered transformer, should have been successfully tested for short circuit withstand capability as per IS 2026 Part-5 within last 5 years. The criteria for similar transformer is specified in Annexure-J. The relevant Test Report/certificate shall be enclosed along with bid. Further, design review of offered transformer shall be carried out based on the design of reference transformer, which has already been subjected to Short circuit tests in lieu of repetition of Short circuit tests. In case, manufacturer has not conducted short circuit test earlier, the same shall be carried out on offered transformer.
However, considering the fact that dynamic short circuit tested design is not available for 765 kV voltage class Auto Transformer & 500 MVA, 400 kV voltage class Auto Transformer and testing of these transformers would require some more time, the above requirement of Dynamic short circuit (DSC) withstand test for these transformers shall be applicable for the projects for which bid invitation date is after 31st August 2023. For these transformers, theoretical evaluation of the ability to withstand the dynamic effects of short circuit, based on calculation and consideration of the design characteristics and manufacturing practices, shall be carried out as per IS 2026-5/IEC 60076-5.
A format (forms part of Annexure-J) filled with data of a typical sample case
Page 2 of 15
PC
Textbox
has been prepared for reference and guidance of utility to compare a Short Circuit tested transformer with the offered transformer in order to verify the similarity criteria as per Annexure J
Further, queries have been received in this office on applicability of subject document for the projects awarded before issuance of the document. In this regard, it is clarified that the subject document was issued in April 2021 and shall be applicable for projects which were awarded after the issuance of the document. Similarly, another document “Standard Technical Specification of transformers for Solar Park Pooling Station” was issued in June 2021 and shall be applicable for projects, which were awarded after the issuance of the document.
/ Regards
( / Akshay Dubey) % / Deputy Director
Page 3 of 15
New Delhi - 110001
ft-gi,iai-dq +rq qrk rr{r
=r$ ffi-rtooor re|€ : 237't 027 1 I 237 1 1 31 6
Fax :23721487 E-mail : [email protected]
Secretary Govemment of lndia
The complexity of lndian Power System has increased manifold with formation of one of the largest single synchronous grid in the world. ln present scenario, the major assets of a power system would play an important role not only in terms of investment but also in terms of availability and reliability of the system.Transformers and reactors as compensating device are the vital & essential assets in Power delivery system. Reliability and availability of such assets play important role in uninterrupted power supply and smooth operation of a power system.
The "Standard specifications and technical parameters for transformer and reactors (66 kV and above voltage class)" is a much awaited technical document thoroughly updated in line with national and international best practices for the benefit of all stakeholders involved. The manual has specifically been prepared keeping in view the domestic as well as international requirement by incorporation of best design practices, quality control and testing requirements.
The uniform practice across the utilities in the country would place all manufacturers at a level playing field and benefit indigenous manufacturers, reinforcing the vision of Aatma-Nirbhar Bharat. lt would provide a further fillip to 'Make in lndia' initiative. This initiative would simplify the procurement process, bringing in faster delivery, overall efficiency, quality and productivity in the entire value chain of transformer / reactor procurement & operation.
I thank members of the Committee and all contributors including officers of Central Electricity Authority (CEA) for their sincere effo(s & invaluable contribution in bringing out this document. Since the consultation with large number of stake holders has already been held, I would urge for adoption of this standard specifications by the utilities and manufacturers across the country in true spirit in order to achieve the ultimate objective of cost effective uninterrupted (24x7) qualily power to all consumers and smooth operation of the Power System.
Feedback from the users for improvement of the document is welcome
(Alok Kumar)
$tR, w.u.u. {rFfq
& REACTORS
3.0 Guaranteed and other technical particulars II-1
4.0 Standard ratings of transformer and reactor II-2
5.0 Performance II-2
validity
II-7
9.0 Design review II-8
10.0 Service condition II-8
11.0 Construction details II-9
13.0 Insulating oil II-26
unit into service for replacement of one of
the single phase transformer/reactor units
of a three phase bank
II-27
II-30
arrangement
II-32
Transformer)
II-32
20.0 Valves II-40
21.0 Cabling II-43
23.0 SCADA integration II-53
Cabinet/Individual Marshalling Box/
control and power circuit
current transformer
30.0 Drawings/documents/calculations II-62
transformer/reactor
II-69
reactor of different make
4.0 Calculation of losses, weight of core and
current density of winding conductor
III-5
3.0 Quality assurance documents IV-6
4.0 Quality during inspection & testing
(including virtual inspection) and inspection
certificates
IV-7
5.0 Inspection and testing
5.1 Factory test 5.2 Stage inspection 5.3 Type tests on fittings
IV-14
works
IV-17
Transformer/ Reactor at site in presence of
manufacturer’s and purchaser’s
representative
V-2
at site
7.0 Drying of wet winding of transformer/
reactor by application of vacuum, Dry
nitrogen gas filling and heating
V-14
filter machine
11.0 Inspection and testing at site V-22
12.0 Pre-Commissioning checks and tests for
transformers and reactors
16.0 Flow chart for erection activities
V-31
MANAGEMENT
2.1 Winding Resistance Measurement VI-3
2.2 Voltage Ratio Test (only for transformers)
VI-5
2.6 Capacitance and Tan delta of Windings VI-10
2.7 Capacitance and Tan delta of Bushings VI-12
2.8 Short Circuit Impedance (only for transformers)
VI-14
2.9 Operational checks and Inspection of OLTC (only for transformers)
VI-14
2.11 Dissolved Gas Analysis (DGA) and Interpretation
VI-16
VI-34
2.15 Moisture Measurement & Control VI-37
2.16 Thermo Vision Scanning VI-37
3.0 Remnant Life measurement of Paper
insulation
VI-38
transformer/reactor and other maintenance
6.0 Recommended, as-needed, and optional
maintenance tests as per IEEE Std.
C57.152-2013
VI-41
Reactor
VI-43
Reactors
VI-46
Annexure–B: Technical Parameters of Bushing Current Transformers & Neutral
Current Transformers
Annexure–C: Guaranteed & Other Technical Particulars
Annexure–D: Test Plan and Procedures
Annexure–E: Standard Manufacturing Quality Plan
Annexure–F: Typical Example for Calculation of Flux Density, Core Quantity, No-
Load Loss and Weight of Copper
Annexure–G: Basic Manufacturing Facility & Manufacturing Environment
Annexure–H: List of Drawings/Documents to be submitted by the manufacturer
Annexure–I: Scope of Design Review
Annexure–J: Criteria for selection of similar reference transformer for dynamic
short circuit withstand test
Annexure–K: Painting Procedure
Annexure–M: Standard Dimensions for Lower Portion of Condenser Bushings
Annexure–N: Connection Arrangement for Bringing Spare Unit into Service for
Replacement of One of the Single Phase Transformer/Reactor Units
of a Three Phase Bank
Annexure-O: Typical Arrangement for Neutral Formation for Single Phase Units
Annexure–P: Physical Interchangeability of Transformers and Reactors of
Different Makes
Annexure–Q:
Standard GA Drawings and Limits of Supply Between Suppliers of Transformer and Dry-Type Cable/GIS Termination for Hydro Plants
Annexure–R: 1100 V Grade Power and Control Cable
Annexure–S: Specification for Oil Storage Tank
Annexure–T: Specification for BDV Test Set & Portable DGA Kit
Annexure–U: Specification for On-line Insulating Oil Drying System (Cartridge type)
Annexure–V: Specification for Oil Sampling Bottles & Oil Syringe
Annexure–W: List of Codes/Standards/Regulations/Publications
Chapter-1
Introduction
The phenomenal growth of Indian Power transmission system has resulted
in the formation of One Nation One Grid, one of the largest single
synchronous Grids in the world. The transmission system establishes the
vital link between the generating source and the distribution system
connected to the ultimate consumer. A Robust, Reliable and Optimally
Planned transmission network would facilitate in achieving ultimate
objective of cost effective delivery of power and providing 24x7 Quality
Power for All consumers at affordable rate. In coming years, huge
generation capacity addition including large scale integration of generation
from renewable sources, expansion of electricity market and exchange of
Power between India & neighboring countries would further require
commensurate expansion & strengthening of the associated Transmission
& Distribution network. The complexity of Indian Power System has
increased manifold over the years. With operation of multiple agencies
(State Utilities, Central Utilities, and Private players) in power sector, high
availability & reliable operation assumes tremendous importance in
present scenario. In such a scenario, the major assets of a power system
would play an important role not only in terms of investment but also in
terms of availability and reliability of the system.
The transformer and reactor are vital and expensive assets in a power
system. The increase in demand for energy will require enhancement in
transformation capacity as well as reactive compensation requirement.
Reliability and availability of such important assets plays an important role
in the smooth operation of a power system. Emphasis needs to be laid on
improved design, quality control during manufacturing, use of right
components/accessories, maintenance and safety during operation of
such vital assets. Generally, due to poor quality of raw material,
workmanship, and manufacturing techniques or due to normal and
abnormal stresses of the system during the operation (like frequent system
faults, over loading, environmental effect, unexpected continuous
operating voltage and over voltage stresses), and poor maintenance
practice, transformers/reactors fail much before their expected life span
(expected life span of about 35 years). The failure of such vital equipment
can have significant economic impact due to high cost, long lead time in
procurement, manufacturing and installation. Long repair time is a matter
of concern in many cases of failure of transformer/reactor. Restoration of
transformer/reactor takes about 3 to 6 months after major repair at
manufacturer’s works depending on the type of repair and procurement of
Chapter-1 : Introduction Page I-2
a new one requires 6-10 months depending on the voltage class of
transformer/reactor.
There is no uniform practice across the utilities in the Country as far as
the technical specification of transformer/reactor is concerned. At present,
same rating/class of transformers/reactors are being designed differently
even for the same user. Even for same specifications, manufacturer review
design for successive tenders considering prevailing market condition. This
results in unnecessary increase in design & manufacturing cycle time,
cost, human efforts & inventories. In view of above there was need to
address this issue and develop a standard/common design & engineering
specification for transformer & reactor incorporating the best practices of
various utilities, latest technological development and future trends, which
would be followed by utilities & manufacturers across the Country. The
objective of this initiative is to formulate a standard document bringing out
critical technical parameters of transformer and reactors which affects the
quality, reliability, efficiency and cost of such assets.
This standardization process shall have following advantages:
• The procurement process will be simplified and delivery time would be
reduced resulting in early completion of project
• Due to standard design, frequent design reviews can be avoided
• Standard ratings and standard civil foundation block would facilitate
interchangeability of different make of transformer / reactor
• Standard fittings and accessories
• Lesser requirement of inventories
Keeping in view above objective, Ministry of Power vide order no.
10/24/2016-PG dated 20.08.16, had constituted a committee under the
Chairmanship of Member (Power System), CEA, with the following
composition:
2. CMD, PGCIL
The Terms of Reference of the Committee are as under:
Chapter-1 : Introduction Page I-3
a) To adopt country wide standard designs of Power transformers for
each class ratings and performance parameter wise (including losses);
b) To reduce lead time, human efforts & errors during the transformer
procurement process by adopting standard losses and detailed
guaranteed technical particular (GTP) format;
c) To adopt specifications and application guides for various fittings and
accessories for the selection and maintenance of transformer
components;
d) To follow the Guidelines for preparation and checking of standard
contract drawings preferred cooler and OLTC control schemes;
e) To adopt standard Manufacturing Quality Plan (MQP) for
manufacturing, testing and packing of transformers to define and
ensure quality for reliability;
f) To enhance the overall efficiency, quality and productivity in the entire
value chain of transformer procurement and operation;
g) To achieve interchangeability of transformers of different make,
procured by different utilities – by standardizing the losses, lay out
and foundation plan of transformers; and
h) To achieve shorter deliveries of power transformers for timely and
speedier completion of projects.
Several rounds of meetings were held in CEA with stake holders, utilities
and manufacturers of transformer, reactor & their accessories for
standardization of Technical Specification so that both utilities and
manufacturers across the Country are benefitted and follow a uniform
practice. Although the terms of reference was focused exclusively for
transformer, but the standardization process has been extended to
cover the specification for the reactor of 220kV and above voltage
system as well.
transformers/reactors of 66 kV and above voltage class. The
document does not cover transformers suitable for Static Var
Compensator (SVC), Static Compensator (STATCOM), traction
transformers, welding transformers, testing transformers, mining
transformers, furnace transformers and inverter transformer for
Renewable generators.
manufacturing, transportation, erection, testing, commissioning and
condition monitoring of transformer/reactor. The commercial
aspects, contractual terms, scope of works for OEM/contractor etc.
may be defined by the utility as per its requirement and practice.
Chapter-1 : Introduction Page I-4
Some important points considered while preparing this document are as
under:
1. The purpose of this document is: (a) to standardize the ratings; (b)
bring uniformity in the design by fixing major technical parameters
including maximum permissible losses, eliminating the need for
capitalisation of losses; (c) facilitate physical inter-changeability of
different makes by standardizing the common mounting
arrangement/foundation plan; (d) improve manufacturing facility,
reliability & quality of supply of Transformer/Reactor from all
manufacturers; (e) achieve cost effective production & faster delivery;
and (f) adoption of Condition Based Maintenance (CBM) practices
across the utilities in the country to assess the health of assets.
2. Attempt has been made to standardize and restrict the number of
ratings of Power Transformers and Reactors at different voltage levels
so that the manufacturers shall have to design and manufacturer
fewer ratings resulting in requirement of less inventory of
components and faster delivery. In the process the focus will be on
quality of production which will be in overall interest of utilities,
manufacturers and the system.
Transformers and reactors have been standardized based on general
practice and most commonly used ratings in India.
POWER/ AUTO TRANSFORMERS:
1. 500 MVA (765/√3)/(400/√3)/33 kV Single Phase Auto
Transformer
Transformer
Three Phase Auto Transformer
Transformer
5. 105 MVA (400/√3)/(220/√3)/33 kV *(400/√3)/(230/√3)/33 kV
Single Phase Auto Transformer
Chapter-1 : Introduction Page I-5
Three Phase Auto
*400/110/33 kV
*220/110 kV
*220/110 kV
Three Phase Power Transformer
11. 100MVA 220/33 kV
Three Phase Power Transformer
Three Phase Power Transformer
Three Phase Power Transformer
Transformer
Transformer
Transformer
Sr. No. MVA Rating Line Voltage Rating Phase Type
1. 315 MVA Generation Voltage/(800/√3)kV Single GT
2. 265 MVA Generation Voltage/(800/√3)kV Single GT
3. 315 MVA Generation Voltage/(420/√3)kV
420(765/3) kV
Tran
sfor
mer
Tran
sfor
mer
1. 110 MVAR 765/3 kV Single Phase
Chapter-1 : Introduction Page I-6
3. 125 MVAR 420 kV Three Phase
4. 80 MVAR 420 kV Three Phase
5. 63 MVAR 420 kV Three Phase
6. 50 MVAR 420 kV Three Phase
7. 50 MVAR 245 kV Three Phase
8. 25 MVAR 245kV Three Phase
Note: Primary voltage rating for Generator Transformers (GTs) could not be
standardized as it depends on generator parameters and system
requirement. The MVA ratings of GTs for thermal plants have been
standardized for different voltage class. The MVA rating for GTs for Hydro
plant may be decided by the respective utility. Although some ratings of
Generator Transformers (GTs) could not be included due to certain technical
limitations, the utility may take the help of this document for such ratings of
GTs as far as possible.
In view of objectives and benefits highlighted in following paragraphs,
utilities are advised to procure transformers and reactors of these
ratings only as far as possible. The transformers/reactors of other
ratings should be procured only under special circumstances, for
example to match with the rating of existing transformer and for
parallel operation.
4. The fixation of maximum permissible loss values for transformers
(No-load loss, Load loss, I2R loss and auxiliary loss) and reactors (I2R
loss and total loss) has been done in consultation with utilities and
manufacturers. The method of calculation of losses has been given
along with a typical example for verifying the guaranteed values and
for measurement at manufacturer works so that all utilities across
the country get transformer and reactor of similar quality and
efficiency. Manufacturer shall…
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