Based on the function performed by the current transformer, it can be classified is follows. Types of transformer different types of transformer. Instrument transformers for metering purposes must have a high degree of accuracy up to class 0. Instrument transformers specifications engineering360. Current and voltage instrument transformers technical and. They provide standardized, useable levels of current or voltage in a variety of power monitoring and measurement applications. With more than 100 years of experience, ge offers a broad array of standard and high accuracy models for revenue metering and system protection applications. Potential and current transformers, ratio and phase angle errors, phasor. A baked varnish coating ensures optimum adhesion between the layers after assembly in the measuring transducer. A complete range of instrument transformers up to 800 kv. Instrument transformer being an analogue device can be attached with the following network systems1. A need to reduce line currents too large for a standard meter. Despite schumachers obvious driving skills and many years of experience, he had no chance of winning.
Instrument current voltage transformers part 1 photo credit. It might appear that the extension of range could be conveniently done by the use of shunts for currents and multiplier for volta. We have broken them up into several different groupings. Morgan lacey in 1925, based on a series of pamphlets entitled transformer abstracts that were. Instrument transformers are also used with protective relays for protection of power system basic function of instrument transformers is to step down the ac system voltage and current. Instrument transformer transformer electric current. The specific performance characteristics of current and voltage instrument transformers are easily determined from the equivalent circuit. Thereby the physical behaviour and the standards regarding instrument transformers are shortly discussed and the necessity of the new perspective for the instrument transformer dimensioning is. Instrument transformers are high accuracy class electrical devices used to isolate or transform. Jan 31, 2015 introduction of instrument transformer a electrical device which help in measurement of high voltage or current. Transformers in conformity with specific country standards can also be supplied as 1675 as 1243, ieee c57. A secondary short circuit will cause the unit to overheat and fail in a very short period of time.
Hence, it is essential to inspect and calibrate those instrument transformers at regular intervals. Find instrument transformers on globalspec by specifications. Ge is an industry leader in the design and manufacturing of high, medium and low voltage instrument transformers. Required to provide accurate data in order to protect and verify revenues, instrument transformers are expected to be highly reliable and operate without fault, often for more than 25 years. The primary winding of the transformer is connected to the high voltage or high current circuit, and the meter or relay is connected to the secondary circuit. Pdf to assess the quality of electricity supply through the power networks it is necessary to use instrument transformers or other devices for. Ge e xd high voltage instrument transformers what is an instrument transformer. Jun 11, 2017 in a power system, the currents and voltages are very large. Current, voltage and combined transformers, oilpaper or gas insulated up to 800. By using low range voltmeter can measure high voltage. An introduction to instrument transformer fundamentals, a discussion on power quality, and a detailed explanation of design considerations to assist in selecting an instrument transformer.
Instrument transformer usually, surface insulation materials made from pressboard and polyester film or pure polyester film are used for electrical insulation. Describes different methods of connecting current transformers cts and voltage transformers vts in singlephase and polyphase service. Instrument transformers are used for measurement and protective application, together with equipment such as meters and relays. Browse products from schneider electric canada in voltage transformers for instrument transformers instrument transformer. Download documents for instrument transformers instrument transformer. Instrument transformers are used to scale down the voltage or current to a standardized value when voltage or current is too large to be conveniently used by a measurement, protection, or control instrument. Thank you for registering for email from schneider electric. Play now summary this 31minute video explains what instrument transformers are and how they are typically used. This book explains the basic measurement techniques, instruments, and methods used in everyday practice. Instrument transformers figure 10 are used for measuring and control purposes. Providing both the underpinning knowledge and basic calculations needed to understand, specify, use and maintain power protection systems, this book also covers the practical techniques required on a daily basis.
Therefore, their direct measurements are not possible. The various types of transformer shown in the figure above are explained in detail below. By using low range ammeter can measure high current. All merlin gerin instrument transformer s are in conformity with iec standards, sections 2099 24, and recommendations 600441iec 600442. Read pdf abb instrument transformer guide voltage instrument transformers applicaton guide. Instrument transformers reduce the line current and voltage being provided to the customers load to. In power system, the currents and voltages are very large. Instrument transformer basic technical information and. These are used with low range ammeter to measure current in high voltage alternating circuits where it is not practical to connect instrument and meters directly to lines. Pdf application of instrument transformers in power quality. A current transformer with bar primary has 300 turns in its secondary winding. Instrument transformer we supply a wide variety of high quality power instrument transformer models.
For current transformers, the value of the reactance x is determined in a special way so that it. These critical signals provide the basis for circuitbreaker operation under fault conditions, and as such are fundamental to network reliability and security. Describe the characteristics and functions of different types of current transformers. In reality, however, it is not possible to neglect the excitation. Thank you for subscribing to updates from schneider electric. Instrument transformer article about instrument transformer. As a normal transformer, its ratio can be specified as, so if voltage ratio of pt is known and the voltmeter reading is known then the high voltage to be measured, can be determined. The matter presented here is prepared by the author for their respective teaching assignments by referring the text books and reference books. Current transformers current transformer normally known as c. Instrument transformers are used in ac system for measurement of electrical quantities i. Call now 9058505122 instrument transformers instrument transformer. Manufacturer of transformers serving the commercial and industrial marketplace requirements for switchgear, motor control and switchboard transformers. Instrument transformer sale, instrument transformers on sale.
Ge provides a broad range of customizable instrument transformers supporting hv, mv and lv applications, along with a complete line of control and test switches. The transformers are specifically designed to be used with the electrical equipment which falls into a variety of devices known as instruments. Instrument transformer technologies voltage and current. An introduction to instrument transformer fundamentals, a discussion on power quality and a detailed explanation of design considerations in selecting an instrument transformer. Current and voltage instrument transformers applicaton guide for current transformers, the value of the. Similarly, current transformers take a high current and reduce it to typically 5 amps on the secondary winding so that it can be used with a watthour meter, ammeter. Their role in electrical systems is of primary importance as they are a means of stepping down the current or voltage of a system to measurable values, such as 5a or 1a in the case of a current transformers or 110v or 100v in the case of a voltage transformer. Instrument transformers, geh 230 safety precautions contd 6. Never shortcircuit the secondary terminals of a voltage transformer. Transformer book is still in demand is a tribute to the publishers and to the authors who have carried the torch to light our way for 75 years. Digital processing units with a microprocessor, after analoguedigital conversion of the input signal e. Weidmann has long been a trusted supplier to instrument transformer manufacturers around the world. In any electrical system power system, instrument transformers forms part of main components in metering reading instruments, recording instruments, tariff systems, protection and control system applications.
Instrument transformers weidmann electrical technology ag. Instrument transformers comprise a large category of current and potential transformers for various voltage, frequency and physical size ranges. A leading manufacturer of dry and oilfilled, custom engineered instrument transformers. Some conditions which require a current transformer include. Instrument transformer current transformer potential. Nov 17, 2019 instrument transformers provide electrical isolation between high voltage power circuit and measuring instruments. Current transformer selection ct when using a current transformer, fi rst determine the conditions present and determine the proper size of current transformer to use. Instrument transformers is a generic term which refers to either current transformer ct or voltagepotential transformer vtpt as compared to power transformers.
It covers in detail both analogue and digital instruments, measurements errors and uncertainty, instrument transformers, bridges, amplifiers, oscilloscopes, data acquisition, sensors, instrument controls and measurement systems. Current and voltage instrument transformers technical. Basics, maintenance, and diagnostics vii contents continued page 4. This type of transformer is categorized on the basis of a number of turns in the primary and secondary windings and the induced emf.
Temco manufactures a variety of electrical power transformers. Temco has experience manufacturing and selling quality electrical products since 1968. This section describes the specific classes and uses for instrument. In a power system, the currents and voltages are very large. Scribd is the worlds largest social reading and publishing site. Instrument transformer is an electrical device of high accuracy that is used to transform or isolate current or voltage levels. It might appear that the extension of range could be conveniently done by the use of shunts for currents and multiplier for voltage measurement, as in dc.
Custom instrument transformer voltage combinations available contact our team at temco transformer at 5104902187 to get your quote, place your order and arrange for shipping. It provide low range current and voltage to the protection system. Instrument transformer type, application and functions. Check the manufacturers instruction book for pancake gasket. Which reduces the electrical insulation requirement for measuring instruments and protective circuits and also assures the safety of operators. The paper deals in a general way with the whole field of instrument transformer work, and in a more extensive manner with certain developmets and views for which the authors are more particularly responsible. These current transformers are used along with the measuring devices for. Several measuring instruments can be connected through a single transformer to power. Instrumentation and measurement in electrical engineering.
Introduction of instrument transformer a electrical device which help in measurement of high voltage or current. Contents introduction theory of current transformer selection of current transformers theory and selection of. When used for protection purposes, the instrument transformer outputs must accurately represent the transmission line values during both steadystate and transient conditions. Describe some of the transformer monitoring and protection features. Voltage transformers instrument transformers schneider. Current transformers,voltage transformers and instrument. Instrument transformer free download as powerpoint presentation. Instrument transformers may also be used as an isolation transformer so that secondary quantities may be used in phase shifting without affecting other primary connected devices. Figure 1 works well for most instrument transformers. Instrument transformers videos and books alexander. Analogue devices, directly using the supplied signal, 2. Instrument transformers reduce the line current and voltage being provided to the customers load to safe levels for input to solid state meters. Try our instrument transformer today which is high precision class electrical devices utilized to transform or isolate voltage or the current levels. Instrument transformer in power system, the currents and voltages are very large therefore, their direct measurements are not possible.
1418 15 1102 1260 438 1604 669 385 1369 753 671 1257 847 1541 665 516 1471 14 471 373 679 822 315 1406 1248 988 987 652 283 696 1403 203 1064 1203 877 298 226