Materials System Specification
14-SAMSS-536 7 May 2007
Pad-Mounted, Three Phase
Distribution Transformers
Electrical Substations Equipment Standards Committee Members
Ghamdi, Mohammed Ahmed, Chairman
Carlson, Ronald Wayne, Vice Chairman
Maghrabi, Ibrahim Mohammad
Ramadhan, Mohammad Jafar
Hartman, Ralph August
Helfrich, Cory Allan
Refai, Jobran Ali
Stansbury, Merlin Chip
Lowe, John
Ojan, Jawad Ali
Gopal, Uarutharaja
Nazzawi, Abdullah Omar
Fayez, Hamad Abdullah
Saudi Aramco DeskTop Standards
Table of Contents
1 Scope............................................................ 2
2 Conflicts and Deviations............................... 2
3 References.................................................... 2
4 Qualifications................................................ 3
5 Service Conditions........................................ 4
6 General Requirements.................................. 4
7 Construction Requirements.......................... 5
8 Accessories................................................... 7
9 Insulating Liquid............................................ 9
10 Inspection and Testing................................. 9
Data Schedule................................................... 10
Previous Issue: 29 June 2005 Next Planned Update: 6 May 2012
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Primary contact: Carlson, Ronald Wayne on 966-3-8746128
Copyright©Saudi Aramco 2007. All rights reserved.
Document Responsibility: Electrical Substations Equipment 14-SAMSS-536
Issue Date: 7 May 2007 Pad-Mounted, Three Phase
Next Planned Update: 6 May 2012 Distribution Transformers
1 Scope
1.1 This specification defines the mandatory requirements for design, fabrication
and testing of pad-mounted, compartmental-type, self-cooled, three-phase
distribution transformers with fully shielded separable insulated high-voltage
connectors used in primary distribution loops in industrial and residential areas.
1.2 This specification defines the basic features of the equipment required and shall
take precedence over all standards and codes as referenced. The equipment
manufacturer shall ensure that the applicable standards are adhered to in
addition to this specification.
2 Conflicts and Deviations
2.1 If there are any conflicts between this Specification and associated purchasing,
project or engineering documents, this specification shall take precedence.
2.2 Direct all requests to deviate from this Specification in writing to the Company
or Buyer Representative, who shall follow internal company waiver procedure.
2.3 The designation "Commentary" is used to label a sub-paragraph that contains
comments that are explanatory or advisory. These comments are not mandatory,
except to the extent that they explain mandatory requirements contained in this
SAMSS.
3 References
The following is a summary of all the documents which have been mentioned within
this Specification. The specific part(s) of these documents which are applicable have
been identified throughout this Specification.
3.1 Saudi Aramco References
Saudi Aramco Inspection Requirements
Form 175-140200 Pad-Mounted, Three Phase Distribution
Transformers
Saudi Aramco Forms and Data Sheets
Form NMR-7906 Non-Material Requirements for Transformers:
Small, Medium & Large, Power & Distribution
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Document Responsibility: Electrical Substations Equipment 14-SAMSS-536
Issue Date: 7 May 2007 Pad-Mounted, Three Phase
Next Planned Update: 6 May 2012 Distribution Transformers
3.2 Industry Codes and Standards
American National Standards Institute
ANSI/IEEE C57.12.00 General Requirements for Liquid Immersed
Distribution, Power and Regulating
Transformers
ANSI/IEEE C57.12.26 Standard for Transformers Pad-Mounted,
Compartmental-Type, Self-Cooled, Three-
Phase Distribution Transformers for Use with
Separable Insulated High-Voltage Connectors,
High-Voltage, 34500 Grd Y/19920 Volts and
Below; 2500 kVA and Smaller
ANSI/IEEE C57.12.28 Pad-mounted Equipment-Enclosure Integrity
ANSI/IEEE C57.12.29 Switchgear and Transformers- Pad-Mounted
Equipment- Enclosure Integrity for Coastal
Environments
ANSI/IEEE C57.12.90 Test Code For Liquid-Immersed Distribution,
Power, and Regulating Transformers and
Guide for Short-Circuit Testing of Distribution
and Power Transformers
ANSI/IEEE 386 IEEE Standard for Separable Insulated
Connectors for Power Distribution Systems
Above 600 Volts
National Electrical Manufacturers Association
NEMA TR 1 Transformers, Regulators, and Reactors
American Society for Testing and Materials
ASTM D3487 Standard Specification for Mineral Insulating Oil
Used in Electrical Apparatus
International Electrotechnical Commission
IEC 60296 Specification for New Insulating Oils for
Transformers and Switchgear
4 Qualifications
Transformer designs and materials used in the transformers shall have a minimum of
two (2) years verifiable, satisfactory performance and proven field experience.
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Document Responsibility: Electrical Substations Equipment 14-SAMSS-536
Issue Date: 7 May 2007 Pad-Mounted, Three Phase
Next Planned Update: 6 May 2012 Distribution Transformers
5 Service Conditions
5.1 Pad-mounted transformers shall be for outdoor application and shall be for
mounting on a precast concrete pad/foundation. Unless otherwise specified, it
shall be suitable for continuous operation at locations up to an altitude of 1000
meters.
5.2 Pad-mounted transformers supplied under this specification shall be suitable for
use in locations that are subject to sand and dust storms, fog, and airborne
contaminants, including NaCl (Sodium Chloride) to 300 ppm and MgCl
(Magnesium Chloride) to 50 ppm.
5.3 Unless otherwise specified, transformers shall be suitable for use in locations
with the following ambient temperatures: Average monthly normal maximum
(hottest month), 45°C; Average daily temperature (hottest month), 40°C;
Maximum daily peak 50°C. The temperature of metal surfaces exposed to direct
solar radiation can reach 75°C.
6 General Requirements
6.1 Refer to Section 2 for direction on conflict resolution between documents. For
example, if there are any conflicts between this Specification and associated
project or engineering documents, this specification shall take precedence.
6.2 Information Required with Quotation
6.2.1 The Vendor shall supply the following information with the Quotation.
This list is in addition to the information requested within the Quotation
Request or Purchase Order Documents:
a) Conformance test certification.
b) User's list of the same or similar equipment which has been in
service for a minimum of two (2) years.
The list shall indicate as a minimum:
1) User company name
2) Installation site
3) Date of installation
6.2.2 The transformer design shall be tested to demonstrate conformity to the
referenced standards. As a minimum, the conformance tests shall consist
of the routine, and design tests specified in ANSI/IEEE C57.12.00. The
"Conformance test certification" mentioned above shall be endorsed by
an independent testing laboratory or a third party approved by the
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Document Responsibility: Electrical Substations Equipment 14-SAMSS-536
Issue Date: 7 May 2007 Pad-Mounted, Three Phase
Next Planned Update: 6 May 2012 Distribution Transformers
Electrical Standards Committee Chairman and shall provide clear,
traceable evidence that the subject tests were performed. If requested,
the Vendor shall provide all the necessary detailed test information
suitable for independent verification of the test data.
6.3 Language
The English language, in accordance with American usage, shall be used at all
times with respect to documents, drawings, labels and technical terms, procured
or prepared by the Vendor pertaining to any work in accordance with this
document.
6.4 Ratings
6.4.1 Transformers shall be rated in accordance with the "Usual Service
Conditions" as specified in ANSI/IEEE C57.12.00.
Commentary Note:
Specified transformer ratings are based on ANSI standard 65°C rise over
a 30°C average ambient. The kVA rating specified on the data sheet has
been increased (derated) as required by Saudi Aramco Engineering
Standards to obtain a satisfactory site rating for ambient temperatures
higher than 30°C.
6.4.2 Transformer voltage range, KVA ratings, and High Voltage tap range
shall be as specified in ANSI/IEEE C57.12.26.
6.5 Saudi Aramco form NMR-7906 provides information on non-material
requirements.
7 Construction Requirements
Construction and performance shall be in accordance with the latest issue of the
referenced standards unless specifically addressed in this document.
7.1 Bushings
7.1.1 Low Voltage
All current carrying parts of low voltage bushings shall be copper.
Connection surfaces shall be silver or tin plated.
7.1.2 High Voltage
The primary terminations shall be of dead front construction utilizing
externally clamped high voltage epoxy bushing wells suitable for fully
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Document Responsibility: Electrical Substations Equipment 14-SAMSS-536
Issue Date: 7 May 2007 Pad-Mounted, Three Phase
Next Planned Update: 6 May 2012 Distribution Transformers
shielded separable insulated high-voltage connectors in compliance with
ANSI/IEEE 386.
7.2 Compartmentalization
The high-voltage and low-voltage segments shall be compartmentalized by a
suitable metal barrier. The compartments shall be a minimum of 760
millimeters deep unless specified otherwise. Compartment doors shall utilize
stainless steel hinges and hinge pins.
7.3 Cores
Three leg core design is preferred. However, five leg core design is acceptable
provided a core loss test is performed on each core to be used in a core coil
assembly. The core loss test results will be used to match the cores. The core
loss deviation is limited to 10% for cores used in the same core coil assembly.
Commentary Note:
Core loss verified by certified design tests are acceptable and need not be
repeated.
7.4 Impedance
The impedance shall not be less than 4.0% on the lowest voltage tap.
7.5 Interfaces
External fittings for mechanical and electrical field connections such as drain
valves, filter valves and terminals, shall be to ANSI standards. Where an
adapter is used to meet this requirement such an adapter must be permanently
fixed to the transformer.
7.6 Nameplates
7.6.1 Each transformer shall have a nameplate containing the minimum
information as specified for Nameplate C in ANSI/IEEE C57.12.00.
Nameplates shall be in the English language, shall be abrasion-resistant,
stainless steel, and attached with stainless steel hardware. Entries shall
be marked by etching, engraving or other permanent marking method.
7.6.2 The nameplate(s) shall also include the following, which may be on a
separate plate:
1) Manufacturer's plant location
2) Buyer's Purchase Order number
3) Manufacturer's order reference number
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Document Responsibility: Electrical Substations Equipment 14-SAMSS-536
Issue Date: 7 May 2007 Pad-Mounted, Three Phase
Next Planned Update: 6 May 2012 Distribution Transformers
4) Year of manufacture
5) Model number
6) Site KVA rating (value to be inserted by buyer).
7.6.3 Danger and warning labels shall be written in both Arabic and English,
utilizing white characters on a red background. Arabic warning labeling
can be provided by others if approved by the Buyer.
7.7 Paint
7.7.1 A wet paint process is described in the paint system requirements of
ANSI/IEEE C57.12.28. However, an equivalent coating system utilizing
an electrostatic powder coating process is acceptable. The Vendor must
provide evidence that the painting system used is satisfactory for use in
the environmental conditions described in Section 5, Service Conditions
above. The paint color shall be light gray.
Exception:
If otherwise specified by Saudi Aramco, a paint color having a solar
radiation absorption coefficient less than or equal to Munsell 7GY
3.29/1.5 padmount green may be provided.
7.7.2 When specified in the data schedule, the Pad-mounted transformer shall
meet the requirements for Pad-Mounted equipment-enclosure integrity
for Coastal Environments as specified in ANSI/IEEE C57.12.29.
7.8 Mechanical Construction
The transformer tank cover shall be welded or bolted. When bolted, the gasket
shall be neoprene type or equivalent.
7.9 Terminal Arrangement
The high-voltage terminal arrangement shall be for loop feed system.
7.10 Windings
High-voltage windings shall be delta-connected and low-voltage windings shall
be wye-connected. The angular displacement between the high and low voltage
phase voltages shall be 30 degree with the low voltage lagging the high voltage.
8 Accessories
All transformers shall be provided with the following accessories as standard items:
8.1 Pressure Relief Device
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Document Responsibility: Electrical Substations Equipment 14-SAMSS-536
Issue Date: 7 May 2007 Pad-Mounted, Three Phase
Next Planned Update: 6 May 2012 Distribution Transformers
8.2 Temperature Gauge
8.3 Oil Level Gauge
8.4 Pressure Gauge
8.5 Tank Fittings
8.5.1 A one inch NPT upper plug or cap for filling and pressure testing shall
be provided on all transformers.
8.5.2 A one inch NPT drain valve with built-in sampling device shall be
provided for all transformers.
8.6 High Voltage Switches
Each transformer shall have a combination of three switches which will provide
a loop feed and transformer isolation function. Switch characteristics shall be as
follows:
8.6.1 Internal, oil immersed
8.6.2 Each switch shall be 3-pole, 2-position (close-open) gang-operated.
8.6.3 Operating mechanism shall be manually charged, stored-energy, quick-
make/quick-break type in which open and close operations are
independent of operating handle speed.
8.6.4 Load-break and have a minimum continuous current and load-break
rating of 200 amps.
8.7 High Voltage Current-Limiting Fuses
Fuses shall provide interrupting capacity of 50,000A (minimum). The
transformer manufacturer shall size the fuses unless the fuse rating is specified
on the Purchase Order. Fuse selection/design shall be as follows:
8.7.1 Transformers rated up to including 750kVA:
Drywell, hookstick operated fuse holders equipped with general purpose
current limiting fuses, Fuse holders may be either load break or non-load
break.
8.7.2 Transformers rated more than 750kVA:
Oil immersed current limiting and oil immersed internally mounted
bayonet expulsion fuse coordinated to provide full protection.
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Document Responsibility: Electrical Substations Equipment 14-SAMSS-536
Issue Date: 7 May 2007 Pad-Mounted, Three Phase
Next Planned Update: 6 May 2012 Distribution Transformers
Exception:
Current limiting fuses with drywell canisters are acceptable on
transformers rated 1000 KVA and 4.16 KV or larger.
9 Insulating Liquid
All transformers shall be shipped filled with insulating oil. The oil shall be virgin
hydrocarbon mineral oil specifically manufactured for use as electrical insulating oil.
The oil shall contain no additives, and shall meet IEC 60296 Class 1 or ASTM D3487
Type 1. The transformers shall be supplied with labels stating that they are PCB free.
10 Inspection and Testing
10.1 Inspection
Visual inspection as specified in Saudi Aramco Inspection Requirement Form
175-140200 will include checks for satisfactory workmanship, materials,
freedom from surface defects and for compliance with this Specification,
Purchase Order and Quotation Request.
10.2 Testing
All electrical tests shall be carried out in strict accordance with ANSI/IEEE
C57.12.90 and NEMA TR 1 in so far as this is applicable, and in accordance
with other requirements and standards when specified.
10.3 Conformance/Design Tests
Conformance tests shall be performed on a representative sample transformer of
the design offered by the Vendor.
10.4 Routine Tests
The following routine tests will be performed on each transformer:
1) Winding resistance
2) Ratio
3) Polarity and Phase Relation
4) No-load losses and Excitation Current
5) Impedance Voltage and Load loss
6) Dielectric (Induced potential)
7) Leak test
Revision Summary
7 May 2007 Major revision.
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Document Responsibility: Electrical Substations Equipment 14-SAMSS-536
Issue Date: 7 May 2007 Pad-Mounted, Three Phase
Next Planned Update: 6 May 2012 Distribution Transformers
Data Schedule
Attachment to 14-SAMSS-536
Pad-Mounted Distribution Transformers
Description Buyer's Required Values Vendor's Proposed Values
Three Phase, Three Phase, Three Phase,
60 Hertz, 60 Hertz, 60 Hertz,
Oil-immersed, Oil-immersed, Oil-immersed,
Self cooled, Self cooled, Self cooled,
65°C rise, * 65°C rise, * 65°C rise, *
Delta Primary, Delta Primary, Delta Primary,
WYE secondary WYE secondary WYE secondary
kVA rating 75 kVA ( )
(check as required) 112.5 kVA ( )
150 kVA ( )
225 kVA ( )
300 kVA ( )
500 kVA ( )
750 kVA ( )
1000 kVA ( )
1500 kVA ( )
Primary Voltage
Secondary Voltage
Primary taps: Four 2½% below ( )
Two 2½% above
and two 2½% below ( )
Impedance (4.0% min)
Winding material _____________________ ______________________
High voltage,
internal, loop
feed switch,
current rating
(300 amp min)
High Voltage Fuses: By Manufacturer ( )
________________ Buyer specified (AMPS: )
Enclosure Integrity Standard: ( )
Coastal: ( )
• See paragraph 6.4.1 for temperature rating requirements.~!
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