power systems loss

Typical No-Load loss and Load loss for Power Transformers according to MVA capacity. No-load loss and Load loss in Power Transformers varies significantly depending on different factors. Here you can find the typical value for the no-load loss and load loss according to power transformers having Load Tap changers and those having none. Different MVA capacity means also having different values for the power transformers' no-load and load loss.

Principles in using single-phase transformers to create a three-phase banks. There can be advantages to using single-phase transformers to make a three- phase bank instead of building a three-phase unit. For instance, it may be impossible or impractical to fabricate or ship a three-phase transformer with an extremely large MVA capacity.

What are the disadvantages in using y-y connection? The Y-Y transformer connection was poorly understood in the early days of power engineering and it received a very bad reputation when it was first used; in fact, this connection was avoided for a long time until its limitations were overcome by good engineering practice. Some of the inherent disadvantages of the Y-Y connection are discussed below:

What are the advantages in using y-y connection? Although care must be exercised when using the Y-Y connection , this connection has certain inherent and important advantages over other three-phase transformer connections. The following are some of the advantages of using y-y connection in an electrical system.

What are the principles behind the y-y configuration? The most obvious way of transforming voltages and currents in a threephase electrical system is to operate each phase as a separate singlephase system. This requires a four-wire system comprised of three phase wires plus a common neutral wire that is shared among the three phases. Each phase is transformed through a set of primary and secondary windings connected phase-to neutral. This is commonly referred to as the Y-Y connection, as illustrated in Figure 9.1. The left-hand part of Figure 9.1 shows the physical winding connections as three separate twowinding transformers.

LOADING POWER TRANSFORMERS BEYOND NAMEPLATE RATING:SIMULATION SOFTWARE VIDEO Power transsformers are one of the most critical asset in any power system network. Transformers undergoe different load cycles that vary depending the time of day and year in power system conditions. For example, the daily load cycle tends to increase during the early hours of the morning before people leave for work and in the evning after they arrive home. Similarly, a yearly load cycle during the hot summer months when high ambient temperature cause consumers to ramp up their air conditioners and use more electrical power. During contingecy conditions, single or variuos network elemaents such as transsmission lines, generators or transformers might be isolated from the power system. As a consequence,transformers can become overloaded by reaching magnitudes above its maximum nameplate capability affecting and possible reducing the overall life of the transformer.During transformer overloads, theextra pow...

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...

CONSTRUCTING POWER TRANSFORMERS: VIDEO Construction of power transformers undergoes a rigorous process. A video presentation of ABB shows the step-by-step process in manufacturing this complex electrical power apparatus. Shown also in this video is the part-by-part construction, from winding, core, tank, accesories up to the delivery of the power transformer is clearly explained in this video. ABB is a major transformer manufacturer throughout the world. ABB power transformers are built and designed to meet the individual customer's needs. This experienced attendance to details lies behind the success of ABB's transformers. This approach is carried throughout the manufacturing process: design, core, winding, drying, tank, quality assurance, assembly, testing, transport and installation and support.

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...

ELECTRIC POWER TRANSFORMER ENGINEERING BOOK DOWNLOAD This is an excellent book that tackles all about transformers, and I mean all kinds of transformers. I recommend this book if you want to know more about Power Transformers. Some of the power transformer discussion is about "Rating & Classification", "Efficiency, Losses, &Regulation", "Construction", "Accesory Equipment" and "Modern & Future Dvelopments". Here are some of the topics that are discussed in this book. Power Transformers Distribution Transformers Phase-Shifting Transformers Rectifier Transformers Dry-Type Transformers Instrument Transformers Step-Voltage Regulators Constant-Voltage Transformers Reactors Again, I highly recommend this book. For me, this a complete source for all your information needs regarding transformers. It even includes procedure for Power Transformer Installation. DOWNLOAD THIS BOOK NOW!

PROTECTING POWER TRANSFORMERS FROM COMMON ADVERSE CONDITIONS PDF Power transformers play a significant role in power system delivery. Proper application of relay elements that monitor a transformer’s thermal state and through-faults can provide both short and long term benefits. These benefits include: •  Transformer overload protection, including cyclic overloads •  Continuous transformer thermal status indication that allows the system operator to make transformer loading decisions based on transformer thermal state •  Cooling system efficiency indication •  Records of cumulative per phase I2t values as seen by the transformer •  Settable I2t alarm thresholds that can notify the system operator of excessive through-fault current seen by the transformer •  Cumulative I2tvalues as a measure to prioritize transformer maintenance Overexcitation is a system condition and is not limited to generating stations. Proper application of Volts/Hz e...

POWER TRANSFORMER LIFE-CYCLE COST REDUCTION CASE STUDY ANALYSIS PDF Using long-term thermal loss-of-life analysis, probability of failure analysis, and economic analysis, it is shown that power transformers may be kept in service longer than is the  present policy in many utilities. This analysis, coupled with the use of on-line dissolved gas analysers (DGA’s) and other improved monitoring equipment can instil confidence in a longer in-service life policy for large transformers. An actual Manitoba Hydro transformer replacement scenario is presented. The cost of the monitoring equipment is significantly less than the potential savings. READ MORE >>>

POWER TRANSFORMER MAINTENANCE AND ACCEPTANCE TESTING PDF This manual contains a generalized overview of the fundamentals of transformer theory and operation. The transformer is one of the most reliable pieces of electrical distribution equipment. It has no moving parts, requires minimal maintenance, and is capable of withstanding overloads, surges, faults, and physical abuse that may damage or destroy other items in the circuit. Often, the electrical event that burns up a motor, opens a circuit breaker, or blows a fuse has a subtle effect on the transformer. Although the transformer may continue to operate as before, repeat occurrences of such damaging electrical events, or lack of even minimal maintenance can greatly accelerate the evenhml failure of the transformer. The fact that a transformer continues to operate satisfactorily in spite of neglect and abuse is a testament to its durability. However, this durability is no excuse for not providing the proper care. Most of the corr...

TRANSFORMER TESTS AND MEASUREMENTS Previously, we have discussed that a Power Transformer is the biggest, heaviest and the most expensive piece of equipment that can be found in a substation. Furthermore, the role it plays in the system is also very important that an electric utility can not afford to loss it during its operation. Proper care and maintenance are always carefully observed to ensure that a power transformer is in its top performance. Making sure that it performs well is a priority in every electric distribution utility much more to a commercial company that depends on electric power for its production and a loss of power means also a loss of revenue. To make sure that a transformer is doing its expected performance and future failures could be avoided, tests and measurements are periodically exercised to know whether the said transformer is doing fine or will it need to be replaced. Due to the complexity of the transformer’s construction and operation, plenty of tests ...

TRANSFORMER ENGINEERING:DESIGN AND PRACTICE BOOK By: Shrikrishna V. Kulkarni, S. V. Kulkarni, S. A. Khaparde CHECK OUT THIS BOOK!

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GUIDE FOR THE EVALUATION OF LARGE POWER TRANSFORMER LOSSES This guide is from United States Department of Agriculture Rural Utilities Service RUS Bulletin 1724-301. Stated in this guide is that Losses and Purchase price should be considered when deciding which transformer to purchase. The purpose of this bulletin is to present a uniform approach that can be used to determine the dollar value of these losses over the life of the transformer. The three different types of transformer losses that should be evaluated separately are: a. Load losses (sometimes called copper or coil losses); b. No-load losses (sometimes called core or iron losses); and c. Auxiliary losses (electric fan losses, other such equipment losses).

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.

EFFECTS OF TRANSFORMER LOADING TO LOSSES Transformers, especially substation transformers are subjected everyday to loads that varies in any given period of time. The behaviour of its transformer loading is dependent to the nature of customers that are connected to it. The load profile of residential loads is not identical to the commercial ones the same with the commercial loads not identical to the industrial ones. It is also a given fact that a substation caters a mixture of these loads thus we can conclude that the transformer loading behaviour of one substation will not be necessarily similar to its adjacent substations. Sample of Transformer Loading Profile

AUXILIARY LOSSES IN POWER TRANSFORMER Beside Load loss and No load loss, another type of loss concerning substation transformers and are usually applicable to power transformers that are rated 5000kVA and above is the auxiliary loss. Auxiliary loss is a type loss that represents the electrical load of the transformer auxiliaries. This are the one that are utilize to operate the cooling fans and pumps of the transformer as discussed in our Load Loss topic. Although some utilities disregard this due to the fact that it does not impact the system’s loss in comparison to the Load and No-load losses, still technically they are still considered as losses. On the other hand, some electric utilities installs meters to properly account the power used in operating its substation auxiliaries thus, this can no longer be considered as losses.