power systems loss

DISTRIBUTION TRANSFORMERS – HERMETICALLY SEALED CATALOGUE GUIDE Hermetically sealed oil-immersed distribution transformers according to standards EN 60076 and EN 50464, up to 36 kV. Characteristics • Rated power from 100 up to 2’500 kVA, operating voltages up to 36 kV, 50 Hz • Hermetically sealed execution without air cushion • Tapping range on primary voltage: ± 2x2,5% or according to customer request • Maximum ambient temperature 40°C, average annual temperature 20°C • Maximum temperature rise of copper 65 K, top oil 60 K, natural air cooling ONAN • Maximum installation altitude 1’000 m above sea level • High voltage bushings: plug-in bushings according to DIN 47636 or porcelain bushings according to DIN 42531 for indoor- or outdoor installation • Low voltage bushings: porcelain bushings according to EN 50386 with or without flat connection plate • Compact and leightweight • 2 loss ranges: normal losses and low-loss design • Routine tests according to EN 60076 • Low-ra...

THREE-PHASE, PAD-MOUNTED DISTRIBUTION TRANSFORMERS INSTRUCTION MANUAL FOR UNDERGROUNDSERVICE A step-by-step guide in receiving, commissioning, testing, etc., of pad-mounted distribution transformers provided to us by GE. The equipment covered by these instructions should be operated and serviced only by competent technicians familiar with good safety practices. These instructions are written for such personnel and are not intended as a substitute for adequate training and experience in safe operating procedures for this type of equipment. Receiving Immediately upon receipt of the equipment, and before putting it into service, inspect the transformer for any damage that may have occurred during shipment or storage. If rough handling is evident, file a damage claim with the transport company immediately and notify the nearest General Electric Sales Office promptly. Tighten any parts that may have loosened during shipment. Handling Lifting lugs are provided for lifting the complete ...

A technical paper completed by Juan Carlos Olivares, Member, IEEE, Yilu Liu, Senior Member, IEEE, Jose M. Cañedo, Member, IEEE,Rafael Escarela-Pérez, Member, IEEE, Johan Driesen, Member, IEEE, and Pablo Moreno, Member, IEEE ABSTRACT This paper examines three methods of reducing distribution transformer losses . The first method analyzes the effects of using aluminum electromagnetic shields in a distribution transformer. The goal of placing electromagnetic shields in the distribution-transformer tank walls is to reduce the stray losses. A 500-kVA shell-type transformer was used in the experiments.

POWER SYSTEM HARMONIC EFFECTS ON DISTRIBUTION TRANSFORMERS AND NEW DESIGN CONSIDERATIONS FOR K FACTOR TRANSFORMERS TECHNICAL PAPER A technical paper completed by N.R Jayasinghe, J.R Lucas, K.B.I.M. Perera ABSTRACT This paper presents the effects of harmonic distortion of load current & voltages on distribution transformers, the standard ways of calculating the harmonic effects & design & development of K Factor transformer, which can operate under a specific harmonic environment. The usage of nonlinear loads on power systems has increased the awareness of the potential reduction of a transformer’s life due to increased heat losses. The performance analysis of transformers in a harmonic environment requires knowledge of the load mix, details of the load current harmonic content & total THD. The additional heating experienced by a transformer depends on the harmonic content of the load current & the design principals of the transformer. Both No load & Load loss...

DISTRIBUTION TRANSFORMER LOSSES: TYPICAL TRANSFORMER OPERATION What are the electrical losses that occur in distribution transformers? Our discussions will focus on the losses that occur in electric utilities’ distribution transformers and how these losses differ from power transformers. Due to the significant number of distribution transformer that an electric utility uses, the analysis and understanding of losses that are present must be carefully considered. A significant part of an electric utility’s total system losses takes place in distribution transformers. The primary reason would be because of the numerous units that are needed to cater the many types of consumers in the highly diversified service franchise areas typical of most electric utility. The losses resulting from the large number of installed units are compounded because individual units need to be inexpensive, yet must carry the high amperages of utilization voltage levels. Furthermore, most electric utilitie...

ANSI C57.12.20-1997: STANDARD FOR OVERHEAD TYPE DISTRIBUTION TRANSFORMERS, 500KVA AND SMALLER: HIGH VOLTAGE, 34500 VOLTS AND BELOW: LOW VOLTAGE, 7970/13800Y VOLTAS AND BELOW ANSI standard C57.12.20-1997 on overhead type distribution transformer Scope: This standard is intended for use as a basis for determining the performance, interchangeability, and safety of the equipment covered, and to assist in the proper selection of such equipment. This standard covers certain electrical, dimensional, and mechanical characteristics and takes into consideration certain safety features of single- and three-phase, 60-Hz, mineral-oil-immersed, self-cooled, overhead-type distribution transformers 500 kVA and smaller, with high voltages 34500 volts and below and low voltages 7970/13800Y volts and below. Such transformers may include one or more of the following features: 1) High-voltage, overcurrent protection 2) High-voltage, overvoltage protection 3) Low-voltage, overcurrent protection 4) Low...

IEEE STD C57.12.01-1998: STANDARD GENERAL REQUIREMENTS FOR DRY-TYPE DISTRIBUTION AND POWER TRANSFORMERS INCLUDING THOSE WITH SOLID-CAST AND/OR RESIN-ENCAPSULATED WINDINGS IEEE standard C57.12.01-1998 on distribution transformer Abstract: Electrical, mechanical, and safety requirements of ventilated, nonventilated, and sealed dry-type distribution and power transformers or autotransformers, single and polyphase, with a voltage of 601 V or higher in the highest voltage winding, are described. Information that can be used as a basis for the establishment of performance, interchangeability, and safety requirements of equipment described, and for assistance in the proper selection of such equipment, is given. Introduction: This standard, together with its companion standards documents, represents a new milestone in standards for dry-type transformers, which are becoming increasingly more important with the elimination of askarel insulating fluids in new transformers. This standard is the...

DISTRIBUTION TRANSFORMER INSTRUCTION MANUAL ACCORDING TO SUNBELT TRANSFORMERS What are the procedures followed in dealing with the operation of distribution transformers? SHIPPING Distribution transformers are shipped completely sealed. Core and coils are assembled in a tank with the insulating liquid covering the coils. This method of construction preserves the quality of insulation, the cooling and insulating liquid by preventing contamination from external sources. INSPECTION ON RECEIPT When a transformer is received, a thorough external inspection should be made before the unit is removed from the truck. If there is evidence of damage and/or indication of rough handling in transit, an inspector representing the carrier should be requested and the manufacturer immediately notified. HANDLING The transformer should always be handled in the normal upright position unless information from the manufacturer indicates that it can be handled otherwise. Where a transformer cannot be handl...

AMORPHOUS-METAL FOR DISTRIBUTION TRANSFORMER APPLICATION How does amorphous distribution transformers help in reducing losses in a distribution system? Distribution transformers with amorphous-metal cores were introduced in the early 1980s and have now accumulated many years of in-service time. The amorphous-metal core design results in transformer core losses approximately 70% less than silicon-steel core designs. For example, the core loss for a new 50-kVA amorphous-core transformer might be only 30 watts instead of the 100 watts typical for a 50-kVA unit of conventional low-loss design. Winding losses and impedance are about the same for amorphous-core transformers and silicon-core transformers. The purchase price of a amorphous-core transformer is approximately 25% higher than a conventional-design transformer of the same size and type. From a loss-economics point of view, each distributor should evaluate the equivalent first cost of reduced core losses for each size and type ...

BASIC PARTS OF A SINGLE-PHASE DISTRIBUTION TRANSFORMER AS SEEN BY THE NAKED EYE Basic parts of a distribution transformer that can be virtually seen. Distribution transformers constructions are relatively less complicated compared to a substation transformer. Although both have exactly similar principle of operation and that is to transform voltage from a higher level to a smaller voltage level, their basic parts differs significantly. Distribution transformers are basically categorized into two; pad-mounted and pole-mounted distribution transformers. Pad-mounted distribution transformers are also known as mini-substation transformers. Comparing pad-mounted to pole-mounted, pole-mounted distribution transformers are the type of transformer that we usually see especially in developing countries. Found below are the basic parts of a single-phase pole-mounted distribution transformers we usually see; Transformer tank – this encloses the oil insulation and winding of the transformer....

BASICS OF DISTRIBUTION TRANSFORMERS ACCORDING TO POWERTRANSFORMER.US Review on the basics of a distribution transformer’s principle of operation and construction. Distribution Transformers convert high-voltage electricity to lower voltage levels acceptable for use in homes and business. Electrical energy is passed through distribution transformers to reduce high-distribution voltage levels down to end-use levels. Nearly all energy used in the United States passes through at least one distribution transformer before being consumed by an end-use appliance, motor, or other piece of equipment. Transformers are found in all sectors of the economy: residential, commercial, and industrial. General Purpose Distribution Transformers  They are generally used for supply appliance, lighting, motorized machine and power loads from electrical distribution systems. They are either ventilated or totally enclosed, and are available with either aluminum or copper windings in standard ratings fr...

CLASSIFICATION OF DISTRIBUTION TRANSFORMERS IN AN ELECTRICAL DISTRIBUTION SYSTEM How are distribution transformers being classified according to different parameters? In dealing with distribution transformers, several parameters are always in consideration that describes the factors that a distribution transformer must have. Distribution transformers are classified into several different categories based on certain factors such as: Type of Insulation used – distribution transformer insulation does not only ensures isolation of the transformer windings from other transformer parts (i.e. tank) but also serves as a coolant during rise of temperature. The transformer insulation can be liquid-immersed or dry-type. Liquid-immersed distribution transformers typically use oil to insulate the core and the windings. This oil can either be mineral or synthetic that should be non-flammable. Dry-type on the other hand uses gaseous or dry compound as an insulating medium. Number of phases – d...

DISTRIBUTION TRANSFORMERS IN AN ELECTRICAL DISTRIBUTION SYSTEM Role of Distribution Transformers in an electric utility and its functions? Before voltages are converted into a level which can be utilized by a typical electric utility customer, voltage transformation occurs first in the distribution transformers. The function of a distribution transformer does not differ much of that a power transformer. The only obvious disparity is its voltage level. A distribution transformer basically reduces voltages from medium voltage level to low-voltage level of which that can be readily used by the end-users like in residential and commercials establishments. This voltage level is also termed as the final voltage transformation since this is the level used by the customers. A distribution transformer in an electric distribution system can be either a pole-mounted transformer which is mounted and found attached to a utility pole or a pad-mounted transformer which can be located underground, ...