66kv Transformer Fault Analysis For a 66kV transformer secondary winding deformation fault case, we elaborated
This paper introduces the relevant current standards of power transformers, including national Transformer standards, industry standards, local Transformer standards, group standards, International Electrotechnical Commission (IEC) standards, etc., and comprehensively summarizes the products (technical conditions, testing, transportation, etc.), key The performance and selection of raw materials and components, handover test and preventive test, the standard name and scope of application at each stage, and the standard content to focus on.
It provides current standard support for transformer design, manufacturing, factory acceptance, on-site handover acceptance, operation and maintenance, etc., and also provides technical basis for transformer technical evaluation and fault analysis.
The power system is a system of electric energy production, transmission, distribution and consumption composed of power generation, transformation, transmission, distribution and consumption. Transformers are extremely important substation equipment in power generation, transformation and distribution. It is transmitted to the place where power energy is needed through the transmission line through the transformer. A power transformer is a transformer that converts the AC voltage and current values of one power system into different voltage and current values of another power system to transmit electrical energy;
The distribution transformer is reduced from a higher voltage to the last-level distribution transformer, and is directly used as a power transformer for distribution. Ensuring the safe and economical operation and normal life of transformers and improving their reliability and availability is not only the key to reducing the cost of the power industry, but also the key to ensuring the development of various fields of the national economy.
As early as 1965, the Soviet Union proposed to unify the most common transformer components and parts in a range of transformer series that have been finalized, and if possible, in several series and complete sets of accessories, which is of great importance to the smooth development of the transformer manufacturing industry. Significant; while developing standards for transformers, separate standards for components and parts must also be developed.
With the rapid development of the power system, the number of transformers has increased sharply, the voltage level has developed to 1000kV, and the capacity has developed to 1500MVA. The standard system of transformer product performance, key raw material and component performance, handover acceptance, preventive test and other standard systems is relatively complete, which is of great significance for ensuring and improving product quality.
Product standards are the technical basis for product procurement, design, production, testing, acceptance, use and maintenance;
The handover acceptance standard is to check the quality of the transformer after long-distance transportation and installation, and to establish a comparison benchmark for the long-term operation of the transformer;
Preventive testing standards are designed to detect defects in transformers in operation, prevent accidents or equipment damage.
This paper sorts out the current standards for power transformers in terms of product performance, key raw materials and component performance, handover acceptance, preventive test, etc., and provides current standard support for transformer design, manufacturing, factory acceptance, on-site handover acceptance, operation and maintenance, etc. Provide technical basis for transformer technical evaluation and fault analysis.
The IEC 60076 series of standards falls under International Electrotechnical Commission Technical Committee 14 on Transformers (IEC/TC 14). The GB/T 1094 series of standards are equivalent to the IEC 60076 series of standards but have been modified accordingly. They are the most commonly used product standards for transformers, with a total of 16 items.
IEC 60076 is the basis of this series of standards and mainly proposes ratings and general requirements, requirements for a transformer with tapped windings, connection and connection group designation, nameplate, safety, environmental and other requirements, deviations, routine test items , Type test items, special test items, electromagnetic compatibility, high-frequency operation transients, etc.
Compared with the 2003 version, GB/T 1094.3-2017 mainly adjusted the insulation test sequence and test items; increased the requirements for the operation impact test of the transformer with the highest voltage of 126kV; adjusted the induction withstand voltage (voltage) test based on Ur, And adjusted the pre-applied voltage, measuring voltage, measuring time and partial discharge limit of partial discharge measurement; added the insulation level of transformer windings with nominal voltage of 750 kV and 1000 kV of the system. In GB/T 1094.11, GB/T 1094.13~GB/T 1094.16 are dry-type, self-protection liquid-filled natural cooling, liquid-immersed, gas-filled, and wind power transformer product standards using high-temperature insulating materials.
Standard name: Power transformers – Part 1: General
Standard number: IEC 60076-1-2011
Scope: Applicable to three-phase and single-phase transformers (including autotransformers), but excluding some small and special transformers
Standard name: Power transformers – Part 2: Temperature rise for liquid-immersed transformers
Standard number: IEC 60076-2-2011
Scope: Applicable to liquid immersed transformers, specifies the signs of transformer cooling methods, transformer temperature rise limits and temperature rise test methods
Standard name: Power transformers – Part 3: Insulation levels, dielectric tests and external clearances in air
Standard number: IEC 60076-3-2011
Scope: specifies the relevant insulation tests and minimum insulation test levels used for power transformers. Applicable to power transformers specified in GB/T 1094.1
Standard name: Power transformers – Part 4: Guide to the lightning impulse and switching impulse testing – Power transformers and reactors
Standard number: IEC 60076-4-2011
Scope: is to provide a guideline and make some clarifications to the current methods of lightning impulse and operational impulse testing of power transformers
Standard name: Power transformers – Part 5: Ability to withstand short circuit；
Standard number: IEC 60076-5-2011；
Scope: specifies the requirement that the power transformer should be free from damage under the action of overcurrent caused by external short circuit. The calculation procedure to characterize the heat resistance ability of power transformers to withstand this kind of overcurrent and the special test and theoretical evaluation method to bear the corresponding dynamic stability ability are described;
Standard name: Power transformers – Part 7: Loading guide for oil-immersed power transformers；
Standard number: IEC 60076-7-2011；
Scope: Applicable to oil-immersed transformers, expounds the influence of transformer operation under different ambient temperature and load conditions on its life;
Standard name: Power transformers-Part 8: Application guide；
Standard number: IEC 60076-8-2011；
Scope: suitable for power transformers complying with the IEC 60076 series of standards;
Standard name: Power transformers – Part 10 : Determination of sound levels；
Standard number: IEC 60076-10-2011；
Scope: specifies the measurement methods for sound pressure and sound intensity, which are used to determine the sound power level of transformers, reactors and their installed cooling equipment
Standard name: Power transformers – Part 10 -1: Determination of sound levels – Application guide；
Standard number: IEC 60076-10-1-2011；
Scope: Provide manufacturers and users with a supporting document on how to use the measurement techniques described in GB/T 1094.10. Describes noise sources and characteristics, discusses various factors that may affect the accuracy of measurement methods, and points out why factory measurements differ from field measurements
Standard name: Power transformers – Part 11: Dry-type transformer；
Standard number: IEC 60076-11-2011；
Scope: Applicable to dry-type power transformers (including autotransformers) whose maximum voltage is 40.5kV and below, and at least one winding is higher than 1.1kV; dry-type power transformers suitable for various structures and processes transformer
Standard name: Power transformers – Part 12: Loading guide for dry-type power transformers；
Standard number: IEC 60076-12-2011；
Scope: It is suitable for dry-type transformers within the scope specified in GB/T 1094.11, and provides an estimation method for the insulation aging rate and life loss of dry-type transformers. This method expresses the aging rate and life loss of transformer insulation as the operating temperature and time of the transformer. and load function
Standard name: Power transformers – Part 13: Self-protected liquid-filled transformers；
Standard number: IEC 60076-13-2011；
Scope: Suitable for indoor or outdoor high-voltage/low-voltage self-protected liquid-filled natural cooling transformers with rated power from 50k VA to 1000 k VA, whose primary winding (high voltage) maximum voltage is suitable for equipment below 24 kV; secondary winding (low voltage) ) The maximum voltage is 1.1k V for equipment below 24k V
Standard name: Power transformers – Part 14: Liquid-immersed power transformers using high-temperature insulation materials；
Standard number: IEC 60076-14-2011；‘
Scope: specifies the technical specification, design, test and load information of liquid immersed transformers using high temperature insulating materials or using high temperature insulating materials and conventional insulating materials, and applies to power transformers designed by IEC 60076-1
Standard name: Power transformers – Part 15: Gas-filled power transformers
Standard number: IEC 60076-15-2011
Scope:This applies to three-phase and single-phase gas-filled power transformers (including autotransformers), but does not include some small and special transformers;
Standard name: Power transformers – Part 16: Transformers for wind turbine applications;
Standard number: IEC 60076-16-2011;
Scope: Suitable for dry-type and liquid-immersed transformers for wind power generation with rated capacity from 100 to 10000k VA, the maximum voltage of the equipment is not more than 40.5k V, and the working voltage of at least one winding is not more than 1.1k V
Standard name: Power transformers-Part 18: Measurement of frequency response;
Standard number: IEC 60076-18-2011;
Scope: It specifies the method and equipment for measuring the frequency response of the equipment on site and when it leaves the factory. It can be used for the measurement of new equipment as well as the measurement of equipment in operation. The interpretation and analysis of the measurement results are not part of the normative content of this part, and only some guiding suggestions are given.
Standard name: Power Transformers-Part 2 0 : Energy Efficiency
Standard number: IEC TS 60076-20-2017
Scope: For transformers to which IEC 60076-1 applies
Standard name: 220kV~750kV oil-immersed power transformers using technical conditions
Standard number: DL/T 272-2012
Scope: Specifies the basic requirements to be followed when using oil-immersed power transformers. Suitable for oil-immersed power transformers with a frequency of 50Hz, 220~750kV
Standard name: Technical parameters and requirements for 750kV and 1000kV oil-immersed power transformers
Standard number: NB/T 42020-2013
Scope: specifies the terms and definitions, operating conditions, performance parameters, technical requirements, test items, test methods and requirements, identification, lifting, packaging, transportation and storage, installation and safety of 750, 1000kV single-phase oil-immersed power transformers . Single-phase oil-immersed power transformers for 750 and 1000kV rated at 50Hz
Standard name: Technical guidelines for 10kV on-load capacity regulating transformers
Standard number: DL/T 1853-2018
Scope: specifies the product model, technical requirements and test requirements of the 10kV three-phase oil-immersed on-load capacity regulating transformer. It is suitable for capacity and voltage regulation transformers with rated frequency of 50Hz, 10kV and rated capacity of 100(30)～630(200)k VA. The capacity regulation and voltage regulation involved are not suitable for occasions that require parallel operation and require frequent capacity adjustments (more than 6 times a day) or frequent voltage adjustments (more than 15 times a day).
Standard name: Three-phase oil-immersed capacity regulating transformer
Standard number: JB/T 10778-2020
Scope: specifies the terms and definitions of three-phase oil-immersed capacity regulating transformers, use conditions, product models, capacity regulating and voltage regulating types and capacity conversion methods, performance parameters, technical requirements, tests, nameplates, signs, lifting, packaging, transportation and storage. Suitable for 6 and 10kV, three-phase, oil-immersed, rated frequency 50Hz, “Y-D conversion” capacity regulation mode and rated capacity of 30 (10) ~ 630 (200) k VA non-excitation capacity regulation and voltage regulation distribution transformers And “Y-D conversion” capacity adjustment mode and rated capacity of 100 (30) ~ 630 (200) k VA or “series-parallel conversion” capacity adjustment mode and rated capacity of 100 (25) ~ 630 (160) k VA. On-load capacity regulation and voltage regulation distribution transformers and on-load capacity regulation and non-excitation voltage regulation distribution transformers
Standard name: Combined transformer
Standard number: JB/T 10217-2013
Scope: specifies the terms and definitions, conditions of use, product classification and product model, basic parameters, technical requirements, test methods, inspection rules, nameplates, signs, lifting, packaging, transportation and storage of combined transformers. Suitable for oil-immersed combined transformers with voltage level of 6~35k V, rated frequency of 50Hz, and rated capacity of 30~2500k VA
Standard name: 10kV low maintenance on-load voltage regulation and distribution transformer technical specification
Standard number: T/CEC 163-2018
Scope: specifies the product model, operating conditions, technical parameters and requirements, testing, marking, packaging, transportation and storage of 10kV low-maintenance on-load voltage regulators and distribution transformers. It is suitable for three-phase oil immersion and less maintenance on-load voltage regulation distribution transformers with rated frequency of 50Hz, 10k V and capacity of 100~630k VA
Standard name: 6k V ~ 1000k V power transformer sound level
Standard number: JB/T 10088-2016
Scope: specifies the A-weighted sound level limit for the addition of the no-load sound power level of the power transformer and the sound power level of the load current. It is suitable for 6~1000kV grade silicon steel core oil-immersed power transformers and 6~35kV grade silicon steel core dry-type power transformers.
“Test Guidelines for Power Transformers” JB/T 501-2006, as the basic standard for transformer test methods, has been widely used by transformer manufacturers, testing institutions, and operation and maintenance personnel.
“Transformer product model compilation method” JB/T 3837-2016 unified the transformer model compilation method. The connotation of green products should take into account the characteristics of low energy consumption, low pollutant discharge, low toxicity, easy recovery and reuse, high health and safety, and high quality; scientifically determine the key stages and key indicators of green product evaluation, and establish evaluation methods and indicator systems. . T/CEEIA 366-2019 is a group standard of China Electrical Equipment Industry Association and a technical specification for the evaluation of green design products of power transformers.
The key raw materials of transformers mainly include electrical steel, winding wire, insulating cardboard, insulating molded parts, outlet devices, insulating oil, and the key components mainly include protective devices such as bushings, tap switches, outlet devices, etc., mainly including pressure relief valves, gas relays Wait. Key raw material and component standards.
At present, IEC/TC 14 has formulated the IEC 60076-22 series of transformer product group component standards, including air coolers, water coolers, pumps, communication components, etc. At present, some standards have been officially released, and some standards are still being formulated.
Standard name: Degrees of protection provided by enclosures(IP code)
Standard number: IEC 60529-2013
Scope: Applicable to the protection classification of electrical equipment with a rated voltage not exceeding 72.5kV and protected by an enclosure
Standard name: Fluids for electrotechnical applications – Unused mineral insulating oils for transformers and switchgear
Standard number: IEC 60296-2012
Scope: specifies the terms and definitions, classification and marking, requirements and test methods, inspection rules and marking, packaging, transportation and storage of unused mineral insulating oils. It is suitable for transformers, switches and similar electrical equipments that need to use oil as insulation and heat transfer medium. It is obtained from petroleum distillate as raw material and obtained after refining. Unused mineral insulating oil with and without additives. Generator oil can refer to this standard. Excludes mineral insulating oils made from reclaimed oils.
Standard name: Insulated bushings for alternating voltages above 1000V
Standard number: IEC 60137-2017
Scope: Specifies the characteristics and tests of insulating bushings. It is suitable for bushings used in electrical equipment, transformers, switches and other power equipment and devices in the three-phase AC system with a maximum voltage of 1000V and a frequency of 15-60Hz as defined in Chapter 3. After the agreement between the supplier and the buyer, it can be partially or completely applied to the following situations: bushings for non-three-phase AC systems, bushings for high-voltage DC systems, bushings for test transformers, and bushings for capacitors. The special requirements and tests for transformer bushings also apply to reactor bushings. Suitable for sleeves made and sold separately. Bushings that form part of electrical equipment and cannot be tested in accordance with this standard shall be tested together with the electrical equipment.
Standard name: Tap-changers Part 1: Performance requirements and test methods
Standard number: IEC 60214-1-2014
Scope: specifies the terms and definitions of tap-changers, conditions of use, technical requirements for on-load tap-changers, technical requirements for motor mechanisms of on-load tap-changers, technical requirements for off-excitation tap-changers, Technical requirements of motor-drive mechanism, nameplate, warning signs of off-circuit tap-changer and manufacturer’s instruction manual
Standard name: Tap-changers Part 2: Application guide
Standard number: IEC 60214-2-2019
Scope: The purpose is to assist in the selection of a tap-changer designed to be assembled with the tap-changer of a transformer or reactor, and it also helps to understand the various types of tap-changers and their accessories. Including on-load tap-changers (resistive and reactive) and off-circuit tap-changers
Standard name: Power transformers – Part 22-1: Power transformer and reactor fittings – Protective devices
Standard number: IEC 60076-22-1-2019
Scope: Suitable for protective devices installed on liquid-immersed power transformers according to IEC 60076-1, and reactors with or without oil conservators installed indoors or outdoors according to IEC 60076-6. Provides an overview of the operating conditions, mechanical and electrical requirements common to all equipment related to the safety of machinery with a function of signalling abnormal operating conditions. It also outlines the specific operating requirements of each device and, in some cases, preferred dimensions in relation to interchangeability, as well as type and routine tests to be performed.
Standard name: Power transformers – Part 22-2: Power transformer and reactor fittings – Removable radiators
Standard number: IEC 60076-22-2-2019
Standard name: Power transformers – Part 22-3: Power transformer and reactor fittings – Insulating liquid to air heat exchangers
Standard number: IEC 60076-22-3-2019
Standard name: Power transformers – Part 22-4: Power transformer and reactor fittings – Insulating liquid to water heat exchangers
Standard number: IEC 60076-22-4:2019
Standard name: Power transformers – Part 22-5: Power transformer and reactor fittings – Electric pumps for transformers
Standard number: IEC 60076-22-5:2021
Standard name: Power transformers – Part 22-7: Power transformer and reactor fittings – Accessories and fittings
Standard number: IEC 60076-22-7:2020
Scope: Suitable for protective devices installed on liquid-immersed power transformers according to IEC 60076-1, and reactors with or without oil conservators installed indoors or outdoors according to IEC 60076-6. Outlines operating conditions, mechanical and electrical requirements common to all equipment. It also outlines the specific operating requirements of the device and, in some cases, preferred dimensions in relation to interchangeability, as well as type and routine tests to be performed.
The electrical equipment handover test is mainly used to judge whether the newly installed electrical equipment that has passed the test according to the relevant factory test standards of the country where the transformer is installed has suffered insulation damage or whether its performance has changed during transportation and installation, and whether it meets the requirements of the power system. It also provides basic data for subsequent operation, maintenance and failure analysis.
Preventive testing is an important link in the operation and maintenance of power equipment, and it is one of the effective means to ensure the safe operation of the power system. The preventive test procedure is the insulation supervision work of the power system.
In order to meet the quality inspection and power grid operation needs of 750kV EHV electrical equipment after on-site installation, the on-site handover and preventive test technology of 750kV electrical equipment was studied, and the State Grid Corporation enterprise standard “Preventive Test of 750kV EHV Electrical Equipment” was formulated. Rules”.
Power transformer products (technical conditions, testing, transportation, etc.), performance and selection of key raw materials and components, handover tests, and preventive tests are comprehensive, clear, targeted and applicable.
Familiarity, understanding, correct use, and strict implementation of standards for scientific researchers, designers, manufacturers, and users (purchasers, operation and maintenance personnel, etc.) of transformers and key raw materials and components are the key points to ensure the quality of power transformer manufacturing. and basic guarantee of safe operation.
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