INDEX PAGE
1.0 INTRODUCTION .........................................................................................................................3
1.1 General
1.2 Caution Notes
1.3 Health & Safety
2.0 GENERAL INFORMATION........................................................................................................6
2.1 Arrangements for Transport
2.2 Recommended Inspection
2.3 Description
2.4 Handling of Transformer at Site
2.5 Storage
3.0 INSTALLATION.............................................................................................................................12
3.1 Installation Location
3.2 Assembly
3.3 De-Mounted Radiators
3.4 Bushing Installation
3.5 Pressure Relief Valve
3.6 Pressure Vacuum Gauge
3.7 Rapid Pressure Rise Relay
3.8 Lightning Arrestor
3.9 Cooling Fans
3.10 Installation of Conservator
3.11 Cable Boxes
3.12 Closing
3.13 Inspection
3.14 Torque Values
3.15 Oil Levels
3.16 Vacuum
3.17 Vacuum Filling
3.18 Dehydrating Breather
3.19 Explosion Vent / Pressure Relief Device
3.20 Buchholz Relay
3.21 Temperature Indicators
3.22 Cooling Radiators
3.23 Current Transformers
3.24 Earthing Connection
3.25 Paint Work
3.26 Completion of other Installation Works
4.0 COMMISSIONING.........................................................................................................................24
4.1 Pre-Energizing Tests
4.2 Oil Testing
4.3 Insulation Resistance Test
4.4 Insulation Power Factor
4.5 Transformer Turns ratio
4.6 Excitation Current
4.7 Bushing Power Factor
4.8 Winding Resistance Test
4.9 Control Circuit Tests
4.10 Fans and Pumps
4.11 Leak Testing
3
4.12 Determining Dryness
4.13 Final External Inspection
4.14 Energization
4.15 Operation
5.0 MAINTENANCE.............................................................................................................................31
5.1 Routine DGA Testing
5.2 External Inspection
5.3 Periodic Inspection
5.4 Maintenance Schedule
5.5 Care of Oil
6.0 BASIC TROUBLE SHOOTING...................................................................................................38
6.1 Replacement Parts
6.2 PCB Certification
6.3 Important Receiving information
7.0 SAFETY PROCEDURES DURING INTERNAL INSPECTION AND MAINTENANCE/REPAIRS
4
1.0 INTRODUCTION
1.1 GENERAL
1.1.1 VIRGINIA TRANSFORMER CORP transformers are designed, manufactured, and tested to the
highest standards and are well-known for their quality and reliability in service. With proper installation,
commissioning, protection, and timely maintenance during operation, users should receive decades of reliable
service.
1.1.2 The purpose of this Instruction Manual is to provide guidance on the installation, commissioning and
maintenance of oil-filled transformers. This guide is necessarily general in nature.
1. The successful operation of these transformers is dependent upon proper installation, unloading, and
maintenance.
2. The conditions under which they operate will determine, to some extent, the frequency with which they
should be inspected.
3. A regular program of inspection should be established and rigidly carried out.
In addition to this guide, the manufacturer should be consulted for specific recommendations or special
conditions.
These recommendations apply to modern, large, liquid-filled power transformers with high-voltage windings
rated 69 kV and above. However, appropriate passages may be applied to lower-voltage transformers when
similar conditions and similar transformer construction exist.
1. Increased applications of large capacity, high-voltage transformers with reduced basic impulse level
(BIL) has led to the need for increasing care during installation and service.
2. High-voltage transformers, with even higher dielectric and thermal stresses, require a correspondingly
high degree of care during installation and operation.
3. To maintain the dielectric strength of the insulation system, it is essential to avoid moisture and entrapped
gas bubbles. Since the dielectric liquid is an essential portion of the insulation system, liquid quality, and
care in handling of the liquid, are extremely important.
4. Large power transformers are usually shipped without liquid, to reduce weight. To prevent the entrance
of moisture during transit, the tank is filled with dry air or dry nitrogen under pressure. To ensure a
continuous supply of dry gas, a transformer is often shipped with a gas bottle and a pressure regulator
connected to its tank.
NOTE—In some cases, transformers are partially or completely liquid-filled when received, in which case the
instructions relative to initial filling may be disregarded. It may not be necessary to drain this liquid from the
transformer except as required for inspection and repair. However, if any part of the main insulation system is
exposed to air or nitrogen, it may be desirable to drain the oil and refill the unit under vacuum, particularly for
higher voltage units, such as 130 kV and above.
At the installation site, all reasonable precautions should be exercised to avoid exposure of the insulation systems
to moisture. Prior to starting installation of the transformer, a detailed procedure for handling, inspecting,
assembling, vacuum treating, oil filling, and testing of the transformer should be developed.
CAUTION: Lethal voltages will be present inside all transformer tanks, enclosures, and at all external
connection points. Installation and maintenance should be performed only by experienced and qualified
personnel accustomed to working with such electrical equipment. De-energize the transformer before
performing any maintenance or service work.
1.1.3 The transformer, along with all its accessories and fittings should be installed, commissioned, operated and
maintained under the supervision of a competent electrical engineer in accordance with relevant statuary
5
requirements and good engineering practice, including Code of Practice, where applicable, and properly used
within the terms of specification.
1.1.4 For the Domestic/International Standards & Codes of Practice, reference should be made to the current
edition publications of ANSI/IS/IEC/BS or equivalent standards.
1.1.5 A list of Standards & Codes of Practice for selection, construction, application and operation of various
transformers will be furnished on request to suppliers.
1.2 CAUTION NOTES
1.2.1 No transformer should have rated service voltage applied to it until ALL preliminary work and precommissioning
tests and checks have been satisfactorily completed.
1.2.2 No high voltage tests should be applied to any transformer without making reference to the supplier.
1.2.3 A transformer which has been commissioned and then removed from service for a long period of time
should be rechecked prior to re-energizing and placing the transformer back into service.
1.3 HEALTH AND SAFETY
1.3.1 Materials or components that are liable to be exposed or handled in normal operation and maintenance, and
which present any hazard to health, are covered here.
1.3.2 During design of an electrical distribution system including a transformer, care should be taken with all of
the following aspects:
a) selection of transformer installation site having adequate ventilation; normal operating temperature;
protection against fire, moisture, explosion, etc.
b) selection of electrical protection at both primary and secondary site against overload, short circuit, earth
fault, etc.
c) provision for regular inspection and maintenance
1.3.3 In addition to the instruction given in this manual, IS / BS / IEC or equivalent standards and local regulation
should also be referred to for other details regarding design, materials and performance.
1.3.4 Excessive and prolonged skin contact with transformer oil (mineral oil) should be avoided. For further
information regarding oil handling, please refer to the guidelines 'Effect of Mineral Oil on the Skin’ & 'Cancer of
the skin caused by Oil’.
1.3.5 A list of standards applicable to distribution transformer is as follows:
a) Power Transformer - IEC:76
b) Bushings for alternating voltage above 1000V - IEC:137
c) Loading guide for oil immersed transformer - IEC:354
2.0 GENERAL INFORMATION
2.1 Arrangements for Transport
2.1.1 Each oil-filled transformer is thoroughly dried out before dispatch. Oil, whether in the transformer tank or
in separate drums, has been thoroughly filtered prior to shipment.
2.1.2 Parts that are liable to be damaged in transit are removed and dispatched in separate cases from the
transformer itself. Accessories such as radiators, bushings, explosion-vent, dehydrating breathers, buchholz
relays, temperature indicators, pressure relief device, conservator, etc., may be removed before shipment.
Distribution transformers can be shipped complete, in standard shipping containers.
6
2.1.3 Weatherproof blanking plates are provided where necessary. Due to transport limitation, and for
convenience of storage/handling at site, if a unit can be dispatched completely assembled, then the transformer is
usually dispatched from the factory with oil covering the core and winding, with the balance of oil shipped in
separate sealed drums, and the other accessories or fittings shipped in separate packages.
2.1.4 The transport oil quantity and the parts removed for transport are generally indicated on Sheet 34 (that
indicates parts shipped separately) or the Packing List that is furnished along with the unit during delivery.
Re-assembly of these parts should be carried out in such a manner that the tank is open to the atmosphere for a
minimum amount of time.
2.1.5 Impact recorders may be used at the discretion of the manufacturer or requested by the user to monitor the
equipment during shipment.
“An impact recorder, which records the g-force magnitudes of impacts versus time, should be affixed firmly
to a structural component of the transformer main tank to minimize any high-frequency resonance that may
occur as a result of unsupported structures. In addition,
หน้าดัชนี1.0 INTRODUCTION ......................................................................................................................... 3ทั่วไป 1.11.2 หมายเหตุความระมัดระวัง1.3 สุขภาพและความปลอดภัย2.0 GENERAL INFORMATION........................................................................................................ 62.1 จัดเตรียมสำหรับการขนส่ง2.2 ตรวจสอบแนะนำ2.3 คำอธิบาย2.4 การจัดการหม้อแปลงไฟฟ้าที่2.5 เก็บ3.0 INSTALLATION............................................................................................................................. 123.1 ตำแหน่งการติดตั้ง3.2 แอสเซมบลี3.3 Radiators ยกเลิกติด3.4 ติดตั้งบูช3.5 วาล์วแรงดันบรรเทา3.6 ความดันเกจสุญญากาศ3.7 รีเลย์แรงดันอย่างรวดเร็วขึ้น3.8 ฟ้าผ่า Arrestor3.9 พัดลมระบายความร้อน3.10 ติดตั้งระบายความร้อน3.11 กล่องเคเบิ้ลปิดที่ 3.123.13 ตรวจสอบ3.14 ค่าแรงบิด3.15 ระดับน้ำมัน3.16 สุญญากาศ3.17 บรรจุสูญญากาศ3.18 ลมที่ขจัดน้ำออกไป3.19 กระจายระบาย / อุปกรณ์บรรเทาความดัน3.20 บุคโฮลซ์รีเลย์3.21 ตัวบ่งชี้ที่อุณหภูมิ3.22 Radiators ที่ระบายความร้อน3.23 ปัจจุบัน3.24 earthing เชื่อมต่อระดับ 3.25 งานสีสวย 3.26 อื่น ๆ งานติดตั้งเสร็จสมบูรณ์4.0 COMMISSIONING......................................................................................................................... 244.1 ก่อนคอร์ทดสอบ4.2 ทดสอบน้ำมัน4.3 ทดสอบความต้านทานฉนวน4.4 ตัวประกอบกำลังของฉนวน4.5 อัตราส่วนการเปลี่ยนหม้อแปลง4.6 ปัจจุบันในการกระตุ้น4.7 กระแทกตัวประกอบกำลังไฟฟ้า4.8 ทดสอบความต้านทานขดลวด4.9 ควบคุมวงจรทดสอบ4.10 และปั๊ม4.11 รั่วไหลในการทดสอบ34.12 กำหนดความแห้งกร้าน4.13 ตรวจสอบภายนอกสุดท้าย4.14 energization4.15 การดำเนินงาน5.0 MAINTENANCE............................................................................................................................. 315.1 ทดสอบ DGA ตามปกติ5.2 ตรวจสอบภายนอก5.3 ตรวจสอบเป็นครั้งคราว5.4 กำหนดการบำรุงรักษา5.5 ดูแลน้ำมัน6.0 BASIC TROUBLE SHOOTING................................................................................................... 386.1 อะไหล่ทดแทน6.2 รับรอง PCBข้อมูลสำคัญรับ 6.37.0 ขั้นตอนความปลอดภัยในระหว่างการตรวจสอบภายในและการบำรุงรักษา/ซ่อมแซม41.0 แนะนำทั่วไป 1.11.1.1 เวอร์จิเนีย CORP หม้อแปลงหม้อแปลงออกแบบ ผลิต และทดสอบการมาตรฐานสูงสุดและเป็นที่รู้จักสำหรับคุณภาพและความน่าเชื่อถือในบริการของพวกเขา ติดตั้งที่เหมาะสมทดสอบการเดินระบบ ป้องกัน และบำรุงรักษาเวลาในการดำเนินการ ผู้ควรรับของที่เชื่อถือได้บริการ1.1.2 วัตถุประสงค์ของคู่มือนี้จะให้คำแนะนำในการติดตั้ง ทดสอบการเดินระบบ และบำรุงรักษาหม้อแปลงไฟฟ้าน้ำมันเติม คำแนะนำนี้ไม่จำเป็นทั่วไปในธรรมชาติ1. การดำเนินงานที่ประสบความสำเร็จของหม้อเหล่านี้จะขึ้นติดตั้งเหมาะสม การโหลด และmaintenance.2. The conditions under which they operate will determine, to some extent, the frequency with which theyshould be inspected.3. A regular program of inspection should be established and rigidly carried out.In addition to this guide, the manufacturer should be consulted for specific recommendations or specialconditions.These recommendations apply to modern, large, liquid-filled power transformers with high-voltage windingsrated 69 kV and above. However, appropriate passages may be applied to lower-voltage transformers whensimilar conditions and similar transformer construction exist.1. Increased applications of large capacity, high-voltage transformers with reduced basic impulse level(BIL) has led to the need for increasing care during installation and service.2. High-voltage transformers, with even higher dielectric and thermal stresses, require a correspondinglyhigh degree of care during installation and operation.3. To maintain the dielectric strength of the insulation system, it is essential to avoid moisture and entrappedgas bubbles. Since the dielectric liquid is an essential portion of the insulation system, liquid quality, andcare in handling of the liquid, are extremely important.4. Large power transformers are usually shipped without liquid, to reduce weight. To prevent the entranceof moisture during transit, the tank is filled with dry air or dry nitrogen under pressure. To ensure acontinuous supply of dry gas, a transformer is often shipped with a gas bottle and a pressure regulatorconnected to its tank.NOTE—In some cases, transformers are partially or completely liquid-filled when received, in which case theinstructions relative to initial filling may be disregarded. It may not be necessary to drain this liquid from thetransformer except as required for inspection and repair. However, if any part of the main insulation system isexposed to air or nitrogen, it may be desirable to drain the oil and refill the unit under vacuum, particularly forhigher voltage units, such as 130 kV and above.At the installation site, all reasonable precautions should be exercised to avoid exposure of the insulation systemsto moisture. Prior to starting installation of the transformer, a detailed procedure for handling, inspecting,assembling, vacuum treating, oil filling, and testing of the transformer should be developed.CAUTION: Lethal voltages will be present inside all transformer tanks, enclosures, and at all externalconnection points. Installation and maintenance should be performed only by experienced and qualifiedpersonnel accustomed to working with such electrical equipment. De-energize the transformer beforeperforming any maintenance or service work.1.1.3 The transformer, along with all its accessories and fittings should be installed, commissioned, operated andmaintained under the supervision of a competent electrical engineer in accordance with relevant statuary5
requirements and good engineering practice, including Code of Practice, where applicable, and properly used
within the terms of specification.
1.1.4 For the Domestic/International Standards & Codes of Practice, reference should be made to the current
edition publications of ANSI/IS/IEC/BS or equivalent standards.
1.1.5 A list of Standards & Codes of Practice for selection, construction, application and operation of various
transformers will be furnished on request to suppliers.
1.2 CAUTION NOTES
1.2.1 No transformer should have rated service voltage applied to it until ALL preliminary work and precommissioning
tests and checks have been satisfactorily completed.
1.2.2 No high voltage tests should be applied to any transformer without making reference to the supplier.
1.2.3 A transformer which has been commissioned and then removed from service for a long period of time
should be rechecked prior to re-energizing and placing the transformer back into service.
1.3 HEALTH AND SAFETY
1.3.1 Materials or components that are liable to be exposed or handled in normal operation and maintenance, and
which present any hazard to health, are covered here.
1.3.2 During design of an electrical distribution system including a transformer, care should be taken with all of
the following aspects:
a) selection of transformer installation site having adequate ventilation; normal operating temperature;
protection against fire, moisture, explosion, etc.
b) selection of electrical protection at both primary and secondary site against overload, short circuit, earth
fault, etc.
c) provision for regular inspection and maintenance
1.3.3 In addition to the instruction given in this manual, IS / BS / IEC or equivalent standards and local regulation
should also be referred to for other details regarding design, materials and performance.
1.3.4 Excessive and prolonged skin contact with transformer oil (mineral oil) should be avoided. For further
information regarding oil handling, please refer to the guidelines 'Effect of Mineral Oil on the Skin’ & 'Cancer of
the skin caused by Oil’.
1.3.5 A list of standards applicable to distribution transformer is as follows:
a) Power Transformer - IEC:76
b) Bushings for alternating voltage above 1000V - IEC:137
c) Loading guide for oil immersed transformer - IEC:354
2.0 GENERAL INFORMATION
2.1 Arrangements for Transport
2.1.1 Each oil-filled transformer is thoroughly dried out before dispatch. Oil, whether in the transformer tank or
in separate drums, has been thoroughly filtered prior to shipment.
2.1.2 Parts that are liable to be damaged in transit are removed and dispatched in separate cases from the
transformer itself. Accessories such as radiators, bushings, explosion-vent, dehydrating breathers, buchholz
relays, temperature indicators, pressure relief device, conservator, etc., may be removed before shipment.
Distribution transformers can be shipped complete, in standard shipping containers.
6
2.1.3 Weatherproof blanking plates are provided where necessary. Due to transport limitation, and for
convenience of storage/handling at site, if a unit can be dispatched completely assembled, then the transformer is
usually dispatched from the factory with oil covering the core and winding, with the balance of oil shipped in
separate sealed drums, and the other accessories or fittings shipped in separate packages.
2.1.4 The transport oil quantity and the parts removed for transport are generally indicated on Sheet 34 (that
indicates parts shipped separately) or the Packing List that is furnished along with the unit during delivery.
Re-assembly of these parts should be carried out in such a manner that the tank is open to the atmosphere for a
minimum amount of time.
2.1.5 Impact recorders may be used at the discretion of the manufacturer or requested by the user to monitor the
equipment during shipment.
“An impact recorder, which records the g-force magnitudes of impacts versus time, should be affixed firmly
to a structural component of the transformer main tank to minimize any high-frequency resonance that may
occur as a result of unsupported structures. In addition,
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