power systems loss

STANDARD ORGANIZATIONS FOR SCADA SYSTEM GUIDE Organization body that standardized the use of SCADA system There are many organizations involved in the standardization of SCADA systems. This section details some of these organizations and the roles they play. The Institute of Electrical and Electronics Engineers (IEEE) The IEEE Standards Association (IEEE-SA) is a membership organization that produces Electrical and IT-Related standards that are used internationally. The IEEE has been involved in standardizing technologies for many years. The following standards have been published by the IEEE with respect to SCADA systems: • IEEE Std 999-1992 – IEEE Recommended Practice for Master/Remote Supervisory Control and Data Acquisition (SCADA) Communications. This recommended practice applies to the use of serial digital transmissions by supervisory control and data acquisition (SCADA) systems having geographically dispersed terminals. These types of systems typically utilize dedicated c...

IEEE GUIDE FOR FIELD TESTING OF RELAYING CURRENT TRANSFORMER C57.13.1 A guide for field testing of relaying current transformer In the application of protective relays, the most widely used input quantity is current. A multiplicity of different protective relays either utilizes current directly, combines it with other currents as in differential schemes, or combines it with voltage to make impedance or power measurements. The source of relay input current is from current transformers which may be located on the bushings of power circuit breakers and power transformers, on the bus bars of metal clad switchgear, or installed as separate items of equipment located as required. Relaying accuracy classes have been established in ANSI/IEEE C57.13-1978, Requirements for Instrument Transformers, to specify the performance of relaying current transformers. During faults on the electric power system, relaying current transformers must operate at high overcurrent levels. ANSI classiÞcations,...

BULLETIN 1724D-112: APPLICATION OF CAPACITORS ON RURAL ELECTRIC SYSTEMS How power factor affect the systems loss in distribution system?                                   UNITED STATES DEPARTMENT OF AGRICULTURE                                                                  Rural Utilities Service                                    ...

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...

IEEE STD C57.93-1995: GUIDE FOR INSTALLATION OF LIQUID-IMMERSED POWER TRANSFORMERS This IEEE standard aims to show the appropriate way of shipping, handling, inspecting, installing, and maintaining liquid-immersed power transformers. Power transformers are defined in this guide to be above 501kVA and which its secondary voltage should be equal or above 1000V. Two sizes of transformers are basically discussed in this guide, those which are 10MVA and above with a primary voltage winding of 69kV and above and transformers which are 501kVA to 10MVA (oil or ail cooled) having a primary voltage winding of 69kV and below. 501kVA TO 10 MVA (OA) LIQUID-IMMERSED POWER TRANSFORMERS This type of transformers are said to be usually a station or pad-mount installed transformers. Its tanks are tightly sealed to preserve the liquid or inert gas used as insulation. Radiators which are usually provided by manufacturer for cooling can be welded directly to the tank. Transformers with lower capacity ar...

TRANSFORMER LOSSES AND THE EFFECT OF HARMONIC CURRENTS ON THESE LOSSES TUTORIAL DISCUSSION (From ANNEX D of IEEE STD C57.110-1998) Power transformers with ratings up to 50 MVA are almost always of core form construction. High-voltage and low-voltage windings are concentric cylinders surrounding a vertical core leg of rectangular or circular cross section. The vertical core legs and the horizontal core yoke members that constitute the magnetic circuit are made up of thin steel laminations. In the top and bottom yoke regions there are usually external clamping structures (clamps) that may be made of either metallic or insulating materials. Oil-immersed transformers are contained within a steel tank, while dry-type transformers may be either freestanding or surrounded by a metal enclosure. If direct current is passed through the transformer winding conductors, a simple I 2R loss will be produced, where R is the dc resistance of the winding. However, if an alternating current (ac) of the...

HARMONICS EFFECT TO TRANSFORMER LOSSES How does harmonics contributes to transformer losses? Harmonics or harmonic distortion in electrical definition is a type of disturbance both found in the voltage and current waveform. Most common source of this distortion is primarily associated with non-linear loads like electronic loads. These electronic loads can either be from a single phase or three-phase form. Harmonics is said to be caused by a non-sinusoidal load currents usually are blamed from commercial power supplies and motor drives like personal computers and other electronically driven devices. Harmonic distortions to either voltage or current are also reflective to the other according to the ohm’s law principle. Previously we have discussed that transformer loss are usually categorized as no-load loss (referred sometimes as excitation loss), load loss (also called as impedance loss), and total loss (the sum of no-load loss and load loss). If you try to recall our discussions re...

IEEE STD C37.91-2000: GUIDE FOR PROTECTIVE RELAY APPLICATIONS TO POWER TRANSFORMER Power Transformers are not only one of the most important piece of electrical device in the power system with respect to its functions but also the most expensive among all other devices found in an electrical substation. Furthermore, once a power transformer is out of service during its operation, the electric utility can not simply replace it in a short period of time not unless one has a spare which is also, mind you, can be very impractical. An electric utility can not afford to loss a power transformer because it would also mean a loss in revenue and for a manufacturer’s perspective is a loss in production. A power transformer, in which I think everybody would agree, is a very complicated form of electrical apparatus. While in operation, it is subjected to a quite number of threats which can be unpredictable, one of which is a fault that can be very damaging. Proper care and maintenance are always...

TRANSFORMER HANDBOOK: ABB This Transformer Handbook prepared by ABB contains a wide range of power and distribution transformers that aims to serve as a guide in understanding, selection, ordering, operation and maintenance of this transformers. The construction of this devices follows standards to the likings of the customers including but not limited to IEC, CENELEC, and ANSI/IEEE. This Handbook although focuses on ABB products, does not significantly differs to the common practice in specifying transformers and ABB based this handbook on their knowledge and experience. Listed below are the main topics that were discussed in this handbook: Every point found in the list are carefully considered. Also, a portion of this handbook tackles all the available standards that are relevant to transformer information. Transformer Types and their Application Quality, Internal Control, Sustainability Loss Capitalization and Optimum Transformer Design Information Required with Enquiry and...

IEEE STD C57.91-1995: GUIDE FOR LOADING MINERAL-OIL-IMMERSED TRANSFORMERS Applications of loads in excess of nameplate rating involve some degree of risk. While aging and long time mechanical deterioration of winding insulation have been the basis for the loading of transformers for many years, it is recognized that there are additional factors that may involve greater risk for transformers of higher megavoltampere and voltage ratings. The risk areas that should be considered when loading transformers beyond nameplate rating are listed below. This guide is applicable to loading 65 C mineral-oil-immersed distribution and power transformers. Guides for loading, IEEE Std C57.91-1981 (prior edition), IEEE Std C57.92-1981, and IEEE Std C57.115-1991 (redesignation of IEEE Std 756) are all combined in this document as the basic theory of transformer loading is the same, whether the subject is distribution transformers, power transformers 100 MVA and smaller, or transformers larger than 100 M...

IEEE STD 62-1995: GUIDE FOR DIAGNOSTIC FIELD TESTING OF ELECTRIC POWER APPARATUS-PART 1: OIL FILLED POWER TRANSFORMERS, REGULATORS, AND REACTORS Majority of the power transformers used by electric utilities are oil-filled including regulators and reactors. Since it is important to have these power apparatus in their top performance, it is therefore imperative to keep its reliability and useful life to the maximum. The early detection of possible defects is very important in this nature of operation. One way of keeping this requirement met is through regular diagnostic evaluation. By testing and measurements, maintenance engineers can be able to know the present condition of these electrical apparatus. However, in order for them to have a reference point they should first establish a benchmark values that future results could be compared to. With these values a clear evaluation can be obtained and to know how the apparatus is doing. Usually this benchmark value is from the first measure...

C57.120.1991 IEEE LOSS EVALUATION GUIDE FOR POWER TRANSFORMERS AND REACTORS   This IEEE loss evaluation guide was made to help electrical practitioners provide a method of establishing the economic value of the electric power intended to supply the losses of a transformer or reactor. With the use of this C57.120.1991 standard, decision-makers can have a guide for the proper weighing of alternatives when it comes to transformer selection that considers the cost-benefit relationship between these choices. Normally, it is a loss evaluation relative to economic benefit of a high-first-cost, low-loss unit against one with a lower-first-cost but with higher losses. Beside the users of transformers, transformer manufacturers can also benefit with this standard by using this as guide a mean to optimize their design and provide the most economical unit to bid and manufacture.

IEEE STANDARD FOR TRANSFORMERS TABLE OF CONTENTS Listed below are some of the IEEE subscription for Power, Distribution and Regulating Transformers. Unapproved drafts are proposed IEEE standards. As such, these documents are subject to change. So, take a precautionary actions in using this standards. Because these drafts are unapproved, they must not be utilized for any conformance/compliance purposes. 1-2000 (R2005) IEEE Recommended Prasctice--General Principles for Temperature Limits in the Rating of Electric Equipment and for the Evaluation of Electrical Insulation 62-1995 (R2005) IEEE Guide for Diagnostic Field Testing of Electric Power Apparatus--Part 1: Oil Filled Power Transformers, Regulators, and Reactors 259-1999 (R2004)    IEEE Standard Test Procedure for Evaluation of Systems of Insulation for Dry-Type Specialty and General Purpose Transformers 315-1975 (R1993) IEEE Graphic Symbols for Electrical and Electronics Diagrams (Including Reference Designat...

Losses in the transmission lines most especially in the overhead bare type of conductors does not only depends on the load it carries or the resistance it possesses. Although these are the major factors to consider, we can not deny the fact that the temperature also contributes a lot. Resistance of any metallic object tends to increase as temperature rises. As a result, we can say that line losses in transmission lines are directly proportional to the temperature.

Corona Loss Power lost due to corona process. On overhead power lines, this loss is expressed in watts per meter (W/m) or kilowatts per kilometer (kW/km). Corona A luminous discharge due to ionization of the air surrounding an electrode caused by a voltage gradient exceeding a certain critical value. Corona, Overhead Power Lines Corona occurring at the surfaces of power-line conductors and their fittings under the positive or negative polarity of the power-line voltage.

The objective of this IEEE standard entitled Standard Definition of Terms Relating to Corona and Field Effects of Overhead Power Lines is to obtain uniformity in the use of terms relating to the areas of corona and the electromagnetic environment of power lines. Its scope is to define the most widely used terms specific to or associated with overhead power-line corona and fields. Here, we are focus more on terms that are relevant to Power System's Loss topic like corona and electric fields that can influence the level of losses in a transmission line. For a complete access on the said standard, you can refer to the link below for the pdf copy.

IEEE Std 524 of 2003 entitled IEEE Guide to the Installation of Overhead Transmission Line Conductors’ scope is focused in providing general recommendations in the selection of tools, equipments and methods that have been found to be practical for the stringing of overhead groundwires and overhead transmission line conductors. The standard also provides a comprehensive list of definitions for equipment and tools used in stringing and for stringing terms commonly employed.