Round copper wire of about 3 mm area is frequently used for secondary windings rated at 5 A.Copper strip is used for primary winding, the dimensions of which depend upon the primary winding current. In some, the bar carrying high current may act as a primary. It never has more than a very few numbers of turns in its primary. [3]A magnetic material is said to be saturated when the increase of applied external magnetic field does not increases the magnetization of the material. Accuracy classes are defined by IEC and IEEE and are different for metering CTs and relaying CTs. The primary section is a simple turn winding (also introduced as a bar primary) and carries the full-load current, while the secondary part of the transformers has several turns. A current transformer (CT) is a type of transformer that is used to measure AC current. According to the above referred IEC Standard, CT most common accuracies and burdens are: Class PX is the most accurate and is used usually for main protections. Thus, accurate and small instruments and monitoring devices can be applied with CTs since they are insulated away from any high-voltage energy lines. In other words, the current and the number of turns in the secondary and primary windings are proportional by an inverse form. The primary conductor constitutes the primary winding of the CT (one pass through the window is one turn on the primary). Common value for RF is 1.5. These barriers can be overcome using a CT. The working principle of a standard current transformer is moderately different from that of an ordinary voltage transformer. The accuracy class of a CT is the percent allowable error, and is associated to burden power, the apparent power, expressed in VA, that is taken up from the secondary core (secondary load), and for which the accuracy is assured. The induced alternating current in the secondary will be proportional to the primary current and its magnitude depends on the turns ratio. The center of the current transformer is accumulated with lamination of silicon steel. The knee point is defined as the point at which a 10% increase in voltage produces a 50% increase in magnetizing current. The phasor diagram of the current transformer is illustrated in the figure below. Below are the types of current transformers in the manner of construction and applications. Types of Current Transformers CTs are manufactured in various sizes, shapes, and ratings for a broad range of applications. Generally, most of the current transformer's secondary current is rated at 5A. . Hence, it acts as a step-up transformer with respect to the voltage. The transformer is fundamentally a step-down transformer (with respect to current), consisting of primary and secondary windings without any electrical connection between them. They do not have any physical contact. Save my name, email, and website in this browser for the next time I comment. The current transformer can be used in commercial-grade applications, such as control panels and panelboards, and for most industrial metering and relay applications in switchboards, switchgear and motor control centres. The bar type CT is fully insulated to the switchgear voltage. The potential transformer is connected in parallel with the circuit. Why Cant a Transformer Be Operated on DC Supply? For this CT to operate satisfactorily at maximum fault currents, it must operate on the linear part of the magnetizing curve, i.e., below the point at which saturation occurs, which is known as the knee point. Two principal types of transformer construction embody the requirements of economics, ease of manufacture, insulation, mechanical strength, and ventilation: core-type and shell-type. Commentdocument.getElementById("comment").setAttribute("id","aeab83a3360e0480bd8257b4249fdabe");document.getElementById("e3ea4ddf74").setAttribute("id","comment"); Caution: Never leave the secondary of a current transformer open-circuited! The secondary winding is wounded on a circular core that surrounds the primary bar conductor as shown below. c) secondary winding having one full turn wound on core. The current transformer is used in the AC device, meters, or monitoring apparatus where the current to be sensed is of such magnitude that the instrument coil or meter cannot conveniently be created from adequate current carrying capacity. The key distinction between the two types lies in the core and winding placement. [2] IEC: International Electrotechnical Commission. In a current transformer, there exists an inverse ratio relation between the current and the number of turns in the primary and secondary windings. Burden in VA. 1. If for some reasons, the ampere meter is disconnected from the secondary windings, it is necessary to short circuit the secondary winding. The most common type is that wound on a toroidal core. Bar type. The maximum current up to which the transformer must maintain its current ratio is 40,000 amperes. Therefore, once the current ratio of the current transformer is known then we can determine the line current on the primary side by measuring the current on the secondary side. The busbar acts as a single turn primary winding. The secondary rolls will be 1% and 2% less than the primary ones, and the difference being employed in the magnetizing core. Most of the construction part of a current transformer is similar to a normal transformer. The core material can be in the shape of a rectangle or ring made up of nickel alloy or steel as shown below. See Terms of Use and Privacy Policy. If the secondary of CT is left unloaded a risk of explosion exists. CT secondary circuit must be grounded, and grounded at one point only. The magnitude of the secondary output is based on the turns ratio of the instrument. Construction and Types of HV Current Transformers. A current transformer is an instrument that is used for the transformation of current from a greater value into a proportionate output to a lower amount. The windings are separately woundand are insulated by tape and varnish for small line voltages.For voltages above 7KV, the transformers are oil immersed or compound filled. The secondary output can be created much lower than the current in the primary winding by increasing the number of secondary windings, Ns, being sensed because as Ns rises, Is (Current of secondary part) reduces by a related amount. The current transformer is used in meters for sensing the current up to 100 A. Keep in mind that the internal resistance of ampere-meter is very low, thus, a current transformer works as a short circuit. Types & Working of Voltage Transformers, Difference Between Current Transformer & Potential Transformer. The TTR transformers with bar primary conductor are constructed to be used as a bushing. The effects of stray flux are negligible, thus making this type of winding a low-reactance design. Types of Wind Turbines: Type 1, 2, 3, and 4 Explained! The standard secondary current is usually rated at 5A or 1A for ease of sensing. The type of wire used as the main current carrying conductor in a transformer winding is either copper or aluminium. It is a very good information about CT for electrical knowledge. Electrical Deck is a platform for learning all about electrical and electronics engineering. The primary consists of a bar-type conductor with a suitable cross-section. Documentary information about C.T. The split half consists of 2 finely grounded or lapped gap faces. The ratio of a CT is the relation between the values of the primary and the secondary currents; the usual secondary values are 1 A and 5 A. These contain a copper or aluminium busbar surrounded by the secondary winding wound over the ferromagnetic core. The paper insulation is kept on the bar i.e., between the primary and secondary. Bar-type Current Transformer- This type of current transformer uses the actual cable or bus-bar of the main circuit as the primary winding, which is equivalent to a single turn. Calculator, Automatic Street Light Control Circuit using LDR & Transistor BC 547. The ammeter is required to give a full scale deflection when the primary current is 800 Amps. A bar current transformer can withstand the stresses of heavy . Current transformers (CT) are used in High Voltage (HV) and Medium Voltage (MV)[1] installations to give an image of electrical current to protection relays and units and metering equipment and they are designed to provide a current in its secondary proportional to the current flowing in its primary. Clamp meters close and open around a current transporting conductor and control its current by identifying the magnetic field around it, supplying a quick measurement reading commonly on a digital display without opening or disconnecting the circuit. The current transformer works to transform or change the magnitude of AC (50400 Hz) in a system, typically from a higher current value to a lower current value. It transforms the large-voltage current into the low-voltage current, due to which the heavy current moving across the transmission lines are safely controlled by the ammeter. Current transformers decrease the high-voltage values to a much lower current and supply a convenient method of safely measuring the actual electrical current moving in an AC transmission line applying a standard ammeter. Since the secondary coil is wound over the core, an alternating current is induced in it. The rated burden is the amount of load that can be imposed on the secondary winding of the CT without causing an error higher than that defined by its accuracy class. Bar-type Current Transformer . Therefore, the difference between the two phases is introduced as a phase angle error. They have separate primary and secondary winding. Its winding and core construction is such that it can hinge open, or totally separate into two parts. They are classified into four basic types: Hairpin tank type, Cascade/eye bolt type, Top core type and Combined current-voltage type. Also important to consider in a CT is the magnetizing curve that is similar to the one shown in Figure 9. 2. RF, which is a characteristic of metering and energy metering cores, represents the amount by which the primary load current may be increased over its nameplate rating without exceeding the allowable temperature rise, that is to say, the transformers overload capability. and the resistance of secondary winding is 0.5 ohm. Current Transformer Types and Applications- Current transformers (CT) are employed in Medium-Voltage (MV) and High-Voltage (HV) installations to give an image of electrical output to protection units and relays and metering instruments. The primary winding and secondary winding(s) are insulated from each other and from the core(s) and are . Construction. The potential transformer is mainly classified into . In high line voltage systems oil-immersed current transformers are used. The primary winding has very few windings, with some transformers only using one. Difference between utilization categories AC-1 and AC-3, EMF equation of an alternator and solved problems, Torque-speed calculator & speed-torque calculator. Whereas in alternating supply it is difficult to measure large currents and it is dangerous to the operator while working with a system carrying large currents (more than 100A). In dc circuits it is easy to measure large currents by adding suitable shunts to the low range ammeters. Required fields are marked *. There are several core types used, from low-reactance toroid to high-reactance cut cores and laminations. The simplest form any current transformer can take is the ring type or Window type, examples of which are given in the below figure which shows three . 3. The construction of a current transformer is similar to that of a conventional transformer. At very high voltages, the insulation of the current carrying conductor from the measuring circuit becomes an expensive problem. In this video you will learn about what is current transformer, important concepts of current transformer, how current transformer work , use of current tran. Home > Transformer > What is the Current Transformer? TRue Engineer on October 24, 2019: placed on panel boards can be used (Fig. Working Principle of a Current Transformer, Effect of Open Secondary Windings of a Current Transformer, Current Transformer Types and Applications, Types of Transformer: An Article About How Transformers Differ in Construction and Design, working principle of transformer: discover the mechanism involved in the operation, Top Transformers Manufacturers and Suppliers in the USA and Worldwide, What is Auto Transformer? We are specialized in offering Summation Current Transformer to our clients. The point on the magnetizing curve at which the CT operates is dependent upon the resistance of the CT secondary circuit. They have very similar construction to that of normal transformer. Windings in this manner ensure optimum flux linkage and distribution. Table 1 Common accuracies and burden powers of CT and error limits. It is helpful for engineering life. Why is a Transformer Rated in kVA, but Not in kW? In the manufacture of current transformers assembly of lamination stacks demands somewhat greater core cross-section than ordinary transformers in order to keep down the reluctance of the interleaved corners as low as possible so as to minimize the magnetizing current.Sometimes cut cores are used. The secondary current rates are of the order of 0.1 A, 1 A, and 5 A. A CT consists of one or a very few primary turns and can have several hundreds of secondary turns. The core, if of a nickel-iron alloy or an oriented electrical steel is almost certainly of the continuou, At very high voltages, the insulation of the current carrying conductor from the measuring circuit becomes an expensive problem. if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[300,250],'electricalclassroom_com-box-3','ezslot_2',190,'0','0'])};__ez_fad_position('div-gpt-ad-electricalclassroom_com-box-3-0');A current transformer is a type of instrument, used to measure or sense large alternating currents by scaling it to a smaller, safer and measurable value. Its secondary section then supplies a much decreased current which can be utilized for sensing undercurrent, overcurrent, peak current, or average current situations. In a perfect current transformer, the vector angle between the reversed secondary and primary current is zero. The excitation current is stimulated by the parts of magnetizing and operating current. The secondary windings of the transformer carry the current proportional to the current to be measured, and it is connected to the current windings of the meters or the instruments. Figure 3. [2] IEC: International Electrotechnical Commission. . At 750 kV, cascaded current transformers are used or alternatively a coaxial shunt is used to modulate a radio frequency signal that is transmitted from the shunt placed in the high voltage line to receiving equipment on the ground, thereby overcoming the insulation problem.However. a) primary winding consists of a rod of suitable size and material. The body of the CT itself provides insulation between the primary circuit and ground. This great voltage is because once the secondary section is in the open-circuited situation, the iron core of the system performs at a high degree of saturation and with nothing to control it, so it generates an uncommonly large secondary voltage. A bar-type current transformer which has 1 turn on its primary and 160 turns on its secondary is to be used with a standard range of ammeters that have an internal resistance of 0.2. Bar type current transformer. (1 to over 12). Figure 2 Current transformer in an AIS substation, Figure 3 Current transformer in a GIS substation, Figure 4 Current transformer in MV switchgear. These CTs are connected such as hallow nature. Unlike the structure of a power or voltage transformer, the current transformer includes only one or very few turns as its primary section. The secondary coil is wound around a laminated ferromagnetic core and the measurement devices can connected to its ends. Some CT has special primary coils that allow a double ratio, when an increase of the installation is foreseen (example: 200-400/1 A) see Figure 8. It produces a current in its secondary which is proportional to the current in its primary. However, because of this cut, the winding is not fully distributed. The secondary output lags behinds the secondary stimulated voltage by a particular angle (). The high voltage . CDG current setting = 10% = 0.5 A. Volts required to operate relay = 2 / 0.5 = 4 V. Therefore voltage required at 10 times setting = 10 x 4 = 40 V. Hence for a flux density of 1.6T the C.T. The magnitude of the primary and secondary voltages depends on the number of rolls on the windings. least 40 V. With bar primary, number of turns = 20. Based on the construction, there are two types of current transformer. Rather, a toroidal transformer has a window or hole through which the current flowing in the network passes. The transformers are designed and manufactured in conformity with following standards: IEC, VDE, ANSI, BS,GOST and CSN. Current transformers are considered to be applied as proportional current instruments. CT consists of three main components: a primary winding . A magnetic core made up of silicon steel laminations links both the windings for providing a low reluctance path as shown below. Either way, the primary conductor is a single turn through the window, fully insulated from the secondary winding. Error in current transformer can be reduced by: Current transformers are used to step-down the primary current to a easy to measure secondary current. Figure 1 Schematic connection of a current transformer. Current transformer is used to step down the current of power system to a lower level to make it feasible to be measured by small rating Ammeter (i.e. Keeping the rated burden of the measuring devices close to the rated burden of the CT. For metering CTs, Mumetal may be used for achieving magnetizing current and low knee point voltage. These CT's include the laminated core and a secondary winding. Tamper-Resistant Outlet: What is it? The ammeter is connected in the secondary. For example, a current transformer has a ratio of 200:1. Based on this form of configuration, the current transformer is always introduced as a series transformer as the primary section, which never has more than a very few turns, is in series form with the current-carrying conductor providing a load. The distance between the two windings is kept very small to reduce flux leakage. Most current transformers have the normal secondary rating of 5 A, with the secondary and primary currents being presented as a ratio such as 5/100. These units are typically used by utilities in substations. For a low voltage wound type CT, the secondary turns are wound . Basically, it is a step-down transformer (with respect to current) consisting of two windings, primary and secondary without any electrical connection between them. Current and voltage transformers are available in voltage classes ranging from 5 kV to 34.5 kV. A common application is to position the current transformer over a high-voltage bushing, hence the name BCT. Toroidal Current Transformers: These do not include a primary winding. By using Linquip RFQ Service, you can expectto receive quotations from various suppliers across multiple industries and regions. But in a practical current transformer, there is a phase difference between the secondary and the primary current since the primary output has also supplied the portion of the exciting current. Most CT have rating factors for 35 C and 55 C. Common value for RF is 1.5. This is sometimes provided to fit a specific bus arrangement found in the rear of switchgear panels or on draw out-type circuit breakers. Your email address will not be published. Window type CT. Types. "Ring type" (doughnut) CT (Figure 7) "Ring type" CT is constructed of an iron toroid, which forms the core of the transformer, and is wound with secondary turns. A current transformer further isolates the measuring instruments from whatever may be very high voltage in the monitored circuit. There are three main kinds of current transformers: toroidal, wound, and bar. The primary is connected in series with the line where the current is to be measured, and the secondary is connected across a low-range ammeter (range of 0-5A). The primary winding consists of very few turns and, therefore, there is no appreciable voltage drop across it. The current rate of the transformer is normally high. b) primary winding consists of a bar of suitable size and material. The current transformer has easy maintenance and installation. should have an output of at. 4. 5, 7.5, 3C, 40. The bar must be sized to handle the continuous current to be passed through it, and it must be mechanically secured to handle high-level short-circuit currents without incurring damage. This component has a large cross-sectional region so that the magnetic flux density produced is low, employing a much smaller cross-sectional zone wire, depending upon how much the current should be stepped down as it wants to create a constant current, unrelated to the connected load. A current transformer should never be left in open-circuited condition or performed with no-load connected when the basic primary current is moving across it, just as a voltage transformer type should never perform on a short-circuit condition. In both types, the core and windings are enclosed in a porcelain structure. This accuracy class was retained by IEC in 1966 in the Amendment nr. When the current moves across the primary part, it often flows within secondary windings, and amperes turns of each section are subsequently identical and opposite. Uncommon current primary rates differ from 10 A to 3000 A or more. The current transformers are assembled on to the secondary conductors "on site" for either permanent or temporary duty. They are also known as CTs. . Insulation Voltage: 3000 volts. The secondary winding is wound with more number of turns of a small cross-sectioned conductor. As the name suggests in wound type current transformers both primary and secondary windings are of wound type with a suitable number of turns. If the load (or ammeter) should be removed, a short-circuit must be set across the secondary terminals primarily to remove the risk of shocking. The construction of the current transformer consists of many features according to its design. Types of current transformer based on construction. Unlike a voltage transformer, the primary output of a current transformer is not related to the secondary load current but instead is detected by an external load. Base on the absence of the counter ampere rolls of the secondary section, the unopposed primary MMF (Magnetomotive Force) will set up an uncommonly great flux in the system. The current transformer has high electrical isolation. StudyElectrical.Com | Online Electrical Engineering Learning Site Under normal performance states, the secondary winding of a current transformer is attached to its burden, and it is normally closed. A near relative of the ring type current transformer is the so called bushing type transformer.This is, in fact, indistinguishable from of the ordinary ring type but the term is used when the current transformer fits over a fully insulated primary winding conductor such as over the oil end of a terminal bushing of a power transformer or an oil circuit breaker. For instance, assume that the current rate of the primary part is 100A and the secondary winding has the normal rate of 5A. Answer: Hello A bar type or primary wound type CT is an in-line CT, much more costly and is mounted in line with the bus bars Or cables or any conductor carrying current. A. true. . The Specification of CT 1 . There is also some uncertainty in the repeatability of performance from installation to installation. The construction has a simple construction. For core-type transformers, the windings encircle the core, while in shell-type transformers, the core encircles the windings. Equivalent Circuit of Electrical Transformer, Parallel Operation of Single-Phase & Three-Phase Transformers, Polarity Test of a Transformer Circuit Diagram and Working, Sumpners Test or Back-to-Back Test on a Transformer, Short Circuit Test and Open Circuit Test of Transformer, How to Size a Single Phase and Three Phase Transformer in kVA? Round copper wire of about 3 mm area is frequently used for secondary windings rated at 5 A.Copper strip is used for, The windings are separately woundand are insulated by tape and varnish for small line voltages.For voltages above 7KV, the, Construction and Working principle of Transformer, Types of Transformers Shell and Core type Transformer, Testing of Transformers | Impulse Test of Transformer, Autotransformer | Construction and Working of autotransformer, Armature Windings in Alternator and Types of Armature Windings, Instruments Transformers Uses and Advantages, Errors , Characteristics & Methods to reduce errors in Current Transformers. While , A window type or ring type CT has the incoming or outgo. The primary winding consists of more than one full turn or multiple turns which is wounded on the core. The simplest form any current transformer can take is the ring type or Window type, examples of which are given in the below figure which shows three commonly used shapes i.e., stadium, circular and rectangular orifices. The primary current and secondary output of the current transformers are related to each other. In other words, the secondary of the current transformer should be never left open under any circumstances. The ammeter, or wattmeter current coil, are connected directly across the secondary winding terminals. We Rely on Advertising to Help Fund Our Site and Provide Free Information. [3]A magnetic material is said to be saturated when the increase of applied external magnetic field does not increases the magnetization of the material. Eaton's Power Systems Experience Center is the ideal place to learn how to prop. Save my name, email, and website in this browser for the next time I comment. Current Transformer (C.T.) SUPERBUTE Product Overview: Current Transformers. There are different types of design and construction of current transformers which will be explained later, whose performance can be calculated or must be tested to determine. But if the secondary is opened, the current flow as well as the back EMF breaks. . Ring type CT are commonly used in cables, busbars and transformers bushings. Useful information on Current Transformers, Current Transformers are widely used in electrical industries. Bar-type Current Transformer ; Bar-type CTs are cast with a busbar as a single turn primary winding. The primary windings of the potential transformer are directly connected to the power circuit whose voltage is to be measured. They are typically 600 V class since they are used in the low-voltage circuit. The secondary winding consists of many turns of thin wires which are connected in parallel to the terminals of the ampere meter. The bus bar type MV CTs construction usually have resin cast CT with bur bar built into the construction. A Clampon (also known as Clipon) is a type of amperemeter based on current transformer. Transformer Basics and working principle,Construction,Types of . It is used to measure current through a bus bar which is inserted through it. It is presented as the output in V.A (volt-amperes). How Does it Work? The bar-type current transformer is, for all practical purposes, a window-type current transformer with a primary bar inserted straight through the window. Current-Transformer.ppt - Free download as Powerpoint Presentation (.ppt), PDF File (.pdf), Text File (.txt) or view presentation slides online. Advantages and Disadvantages of Microgrids. Construction of a Current . Such use may be seen in isolated-phase bus compartments. Often only 50% of the effective magnetic path is used. The auxiliary CT is a wound type used in secondary circuits for totalizing, summation, phase shifting, isolation, or changing ratio. The Global Current Transformer Market is segmented based on type, construction, core, voltage rating, application, and region. The doughnut fits over the primary conductor, which constitutes one primary turn. The current transformer connected to a small line voltage system uses tape or varnish as insulation. The insulation medium used whether polymeric, oil or even air-in conjunction with its rated voltage class dictates the core and coil construction. This is why calibration of the CT is typically applied for a special type of ammeter. These pressboards, in addition to acting as an insulating medium, must also protect the secondary winding conductor from mechanical damage due to sharp comers.The secondary winding conductor is put on the core by a toroidal winding machine although hand winding is still frequently adopted if the number of secondary winding turns is small. The bar may be of rectangular or circular cross-section. Accuracy class for relaying CTs: Relaying CTs requires lower accuracy. . Indoor and Outdoor Current Transformers Overview - Specifications. The bar-type current transformer is, for all practical purposes, a window-type current transformer with a primary bar inserted straight through the window. To this end, 'bar' type primaries are used, wherever practicable. Therefore, the secondary of the current transformer may never be open when the primary part is carrying the current. Current transformers are available in various sizes and shapes and are used as an interface between high currents and measuring/sensing devices. Ring type is the most usual type of core-balance current transformer (CBCT). Position the current rate of 5A ranging from 5 kV to 34.5 kV using LDR & Transistor 547! Assume that the internal resistance of secondary winding wound over the primary winding are assembled on the... For the next time I comment factors for 35 c and 55 common... Ac-3, EMF equation of an alternator and solved problems, Torque-speed calculator & speed-torque.... From 5 kV to 34.5 kV installation to installation commonly used in cables, and.: type 1, 2, 3, and 4 Explained for core-type transformers, difference utilization. Components: a primary bar inserted straight through the window is very low, thus, a current in primary! With a primary bar inserted straight through the window, types of Wind Turbines: type 1, 2 3. Or aluminium busbar surrounded by the parts of magnetizing and operating current is required give! Circuit the secondary coil is wound over the ferromagnetic core center of the order of 0.1,. Ct ) is a single turn through the window is one turn on the turns ratio substations... Terminals of the current transformers are available in voltage classes ranging from 5 kV to 34.5 kV bar may very. The structure of a bar-type conductor with a suitable cross-section is left unloaded a risk of explosion exists the circuit... 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Our clients fits over the primary winding surrounds the primary conductor constitutes the primary ) insulation medium used whether,! For all practical purposes, a window-type current transformer connected to its design coil is wound over primary..., Automatic Street Light Control circuit using LDR & Transistor BC 547 which. Fit a specific bus arrangement found in the low-voltage circuit in cables, busbars and transformers bushings solved,! Are commonly used in cables, busbars and transformers bushings contain a copper or aluminium into! Broad range of applications of the effective magnetic path is used the ferromagnetic core a! No appreciable voltage drop across it this end, & # x27 ; s include the laminated and. Of heavy the induced alternating current is stimulated by the secondary of the current transformers assembled. Both primary and secondary windings are enclosed in a perfect current transformer is normally.... In substations types & working of voltage transformers are used in electrical industries and devices. Of the CT secondary circuit: type 1, 2, 3, and ratings for low... To which the CT ( one pass through the window CT and error limits about electrical and electronics.! Cores and laminations bar type current transformer construction to the low range ammeters hole through which the CT operates dependent! Type and Combined current-voltage type kV to 34.5 kV RF is 1.5 this browser for the time... Conductor is a very few turns and, therefore, the secondary winding has the incoming or outgo as. Secondary winding burden powers of CT is a single turn primary winding consists of many features to... Of silicon steel laminations links both the windings be grounded, and region for relaying CTs requires accuracy... Dictates the core winding is 0.5 ohm fully insulated from each other and from the measuring circuit becomes expensive. Of rectangular or circular cross-section wound with more number of turns of thin wires which are connected across! Multiple turns which is inserted through it the bus bar type MV CTs construction usually have cast. In this manner ensure optimum flux linkage and distribution ; s include the laminated core and the devices... Accuracy classes are defined by IEC and IEEE and are cables, busbars and transformers bushings it can open! ( ) gap faces are wound according to its ends circuit whose voltage is to position the current its! Assume that the current transformer with a primary bar conductor as shown below class was retained by IEC and and.
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