This document and its content, is for authorized company use only1.1 Objective The specification establishes requirements for design, construction and testing of high voltage transformers for onshore and offshore service.The specification contains three parts. Section 2 is valid for all transformers, section 3 is applicable to liquid-immersed transformers, and section 4 is applicable for dry insulated transformers.The referred standards are either based on IEC or based on IEEE. The standards have been referred to by one common number as shown in section 5.3. The IEEE standards are applicable in US or Canada, while IEC standards are applicable elsewhere.SR-47869 - The requirements in this document shall be used in addition to IOGP S-720 specification and datasheet ST518The specification can be used for low voltage transformers, such as 690 - 400 V transformers.1.2 Target group The target group for this document is personnel involved in preparing technical and operational requirements and standards to be applied in project development work for oil and gas.1.3 Provision Provision is made in Management System (TR3020 Electrical, Technical Requirements and Standards).2.1 Neutral points For Neutral Earth Resistors (NER), see requirements in TR3120.2.2 Terminals and wiring Reference is made to TR3120 section 4.11 regarding marking of internal components and wiring.Reference is made to TR3120 section 4.17 regarding light fixture and space heaters inside cabinets.Reference is made to TR3120 section 4.8 regarding earthing of the transformer (high voltage equipment).2.3 Labelling Reference is made to TR3120 regarding the requirements for labelling.2.4 Vibration damper SR-47917 - Use of vibration dampers shall be evaluated to ensure that transformers do not cause unwanted vibration and noise to their surroundings.2.5 Painting SR-98074 - Painting shall be in accordance to TR0042 and IOGP S-715.3.1 Insulating liquid SR-98075 - Use of insulation liquids for allowing temperatures above 105°C, e.g. listed in IEC 60076-14, shall not be used for transformers with U m equal to or above 170 kV for IEC specifications due to the limited experience of dielectric withstand capability of such insulating liquids.The high temperature design should be based on hybrid insulation system. The average temperature rise of the transformer windings at rated power should not exceed 95 K, and the top oil temperature should not exceed 60 K. Reference to other requirements in IEC 60076-14.Minimum thermal class for the high-temperature solid insulation should be 155 °C.SR-47936 - Liquid filled units shall be equipped with man holes to perform access to OLTC, bushings and other internal inspection points if relevant.3.3 Bushings Type of bushings will be described in datasheet.SR-47958 - For plug-in type bushing or equivalent touch proof solution, a portable earthing device shall be delivered, if not otherwise stated.SR-47959 - It shall be provision for measuring voltage at the bushing to be able to check if the transformer is energized.3.4 Tank Transformers with U m equal to or above 24 kV should have a diaphragm-type oil preservation system to avoid direct contact between the transformer oil and air. A flexible diaphragm or bladder should be used for this purpose.SR-47972 - 316L stainless steel shall be used for fasteners (screws, bolts, nuts, etc.) up to and including a diameter of 10 mm. For diameters above 10 mm fasteners shall be hot dip galvanised in accordance with ASTM A153 or coated with PTFE with anticorrosion pre-treatment.The requirement for fasteners does not apply to fasteners inside the transformer tank.4.1 Windings See section 2.3 in this document for general requirements. The insulation level will be according to:List 2 in table 3 of section 12.1 for the IEC-based specification IEC 60076-11. The highest indicated basic lightning impulse level stated in table 5 in section 5.10 for the IEEE based specification IEEE C57.12.01 and IEEE C57.12.91.155°C (insulation class F) for IEC based specifications (IEC 60076-11) 150°C for IEEE based specifications (IEEE C57.12.01 and IEEE C57.12.91).The windings should be solid-casted or VPI. Reference is made to IOGP S-720 datasheet.SR-47991 - All terminals shall be of copper type. This also applies when aluminium windings is specified.4.2 Protective housing See requirements in TR3120. SR-48004 - The transformer shall be in a housing that is cooled by external air or waterSR-48006 - Doors and panels shall be hinged. There shall be isolating bars behind the doors. The bars shall be coloured yellow and black (zebra stripes) if not otherwise required by national regulation.4.3 Testing SR-48016 - The following non-routine tests shall always be performed (ref IEC 60076-11 or IEEE C57.12.01 and IEEE C57.12.91 respectively):Temperature-rise test together with the planned protective housing unless otherwise agreed upon. Partial discharge measurement special test. Determination of capacitances windings-to-earth and between windings for all converter transformers.If several identical transformers are ordered, the non-routine test can be performed on one transformer only.Shall (requirement) Requirement strictly to be followed in order to confirm to the document and from which no deviation is permitted, unless a deviation permit is approved.Should (recommendation) Indicates that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required, or that (in the negative form) possibility or course of action is deprecated but not prohibited.May Indicates a course of action permissible within the limits of the document. Can Statements of possibility and capability, whether material, physical or causal.AC Alternating current AF Air Forced AN Air Natural Converter transformer Transformer feeding a converter load CT Current Transformer DEH Direct Electric Heating IP Ingress Protection NER Neutral Earth Resistor OCTC Off Circuit Tap Changer OFWF Oil Forced Water Forced OLTC On Load Tap Changer ONAF Oil Natural Air Forced ONAN Oil Natural Air Natural• Consolidated with latest versions og EC standards and IOGP standard S-720• Reference update latest versions og EC standards.• Removed requirement who is covered in standards.• Created and implementet an datasheet ST518 in Docmap for in accordance with IOGP S-720Changed some requirement to information element to understand the purpose of some of the requirement.Changes in version 3.02: Document updated from template to template. Wording " hanged toInsignificant changes, performed by system administrator, on behalf of author/owner.Changes in version 3.01: Published in new minor version as part of the GEM-project (Governing Element Management). TR-document is digitalized, and each requirement element is now identified with a unique ID.• General: Editorial changes, updated EC I IEEE references and added references to• Section 2.1: Deleted requirements for base case transformers• Section 2.3: Deleted requirement for uniform winding insulation and included reference to EC 61378-1• Section 2.5: Removed requirement for 110 % core dimensioning is required for all type of transformers• Section 2.11: New section added for vibration dampers• Section 3.6: Updated text and that bushing type will be described in datasheet• Section 3.7: Removed requirement for CT for thermal image• Section 4.3: The transformer core shall be dimensioned for continuous operation at 110 % of rated voltage referred to the principal tapping and rated power.• Section 4.6: Fire class updated from F0 to F15.3 References The documents listed below include provisions and guidelines which, through reference in this specification, constitute provisions and guidelines of this specification.SR-48025 - Latest issue of the referred document shall be used unless otherwise agreed.Other recognized standards may be used provided it can be shown that they meet or exceed the requirements and guidelines of the standards referenced below.Note that references in this specification (e.g. references to clause numbers in standards) are based on year of issue as listed below.Table 1: Standards that are the basis for transformer specificationTest Code for Dry-Type Distribution and Power Transformers2011 IEC 60076-1 Power transformers, Part 1: General 2010 2010 IEEE C57.12.00 IEEE C57.12.90 General Requirements for Liquid- Immersed Distribution, Power, and Regulating Transformers Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers 2011 2010 IEC 60076-2 Power transformers, Part 2: Temperature rise IEEE C57.12.00 General Requirements for Liquid- Immersed Distribution, Power, and Regulating Transformers 2013 2010 IEC 60076-3 IEEE C57.12.00 General Requirements for Liquid- Immersed Distribution, Power, and Regulating Transformers Power transformers, Part 3: Insulation levels, dielectric tests and external clearances in air 2006 2010 IEC 60076-5 IEEE C57.12.00 Power transformers, Part 5: Ability to withstand short circuit General Requirements for Liquid- Immersed Distribution, Power, and Regulating Transformers 2005 2010 IEC 60076-7 IEEE C57.12.00 General Requirements for Liquid- Immersed Distribution, Power, and Regulating Transformers Power transformers, Part 7: Loading guide for oil- immersed power transformers 2005 2010 IEC 60076-10 IEEE C57.12.90 Power transformers, Part 10: Determination of sound levels Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers2004 IEC 60076-11 Power transformers, Part 11: Dry-type transformers 2005 2011 IEEE C57.12.01 IEEE C57.12.91 General Requirements for Dry-Type Distribution and Power Transformers, Including Those with Solid-Cast and/or Resin Encapsulated Windings. Test Code for Dry-Type Distribution and Power Transformers 2008 2005 IEC 60076-12 IEEE C57.12.01 Power transformers, Part 12: Loading guide for dry-type power transformers General Requirements for Dry-Type Distribution and Power Transformers, Including Those with Solid-Cast and/or Resin Encapsulated Windings 2013 IEEE 1276 2000 IEC 60076-14 IEEE Guide for the application of High-Temperature Insulation Materials in Liquid-Immersed Power Transformers Power transformers, Part 14: Design and application of liquid-immersed power transformers using high- temperature insulation materials 2003 2012 IEC 60214-1 IEEE C57.131 Requirements for Load Tap Changers Tap-changers, Part 1: Performance requirements and test methods 2011 1998 IEC 61378-1 IEEE C57.18.10 Converter Transformers, Part 1: Transformers for industrial applications Practices and Requirements for Semiconductor Power Rectifier Transformers 2008 2004 IEC 60137 IEEE C57.19.00 Insulated bushings for alternating voltages above 1000 V General Requirements and Test Procedure for Power Apparatus Bushings 2012 2006 IEC 60296 IEEE C57.106 Fluids for electrotechnical applications – unused mineral insulating oils for Guide for Acceptance and Maintenance of Insulating Oil in EquipmentTR0042 Surface preparation and protective coating TR3120 Electrical equipment, general requirements2012 2008 IEC 61869-2 IEEE C57.13 Requirements for Instrument Transformers Instrument transformers – Part 2: Additional requirements for current transformers 2011 NA NA NA IEC 60076-16 Power transformers, Part 16: Transformers for wind turbine applications