bar type current transformer construction

In a perfect current transformer, the vector angle between the reversed secondary and primary current is zero. A current transformer (CT) is an instrument transformer in which the secondary current is substantially proportional to primary current and differs in phase from it by ideally zero degree.. CT Accuracy Class or Current Transformer Class. Typically, the single straight line considers as primary winding. In high line voltage systems oil-immersed current transformers are used. Bar type current transformers - A bar type current transformer doesn't have a primary winding of its own. An alternating current is passed to the primary of the transformer and the measurement/sensing/protection device is connected to its secondary. A window type CT is rated at 600 volts and has the incoming or outgoing insulated/shielded cables pulled through it. B. false. While aluminium wire is lighter and generally less expensive than copper wire, a larger cross sectional area of conductor must be used to carry the same amount of current as with copper so it is used mainly in larger power transformer applications. Wound type CT is similar to the two winding conventional transformer. a) primary winding consists of a rod of suitable size and material. Accuracy class for relaying CTs: Relaying CTs requires lower accuracy. Ek = 4.44 B A f N. . [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. oil or even air-in conjunction with its rated voltage class dictates the core and coil construction. It is helpful for engineering life. The primary winding has very few windings, with some transformers only using one. 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? According to IEC[2] Standard 61869-2, Clause 5.201, rated primary currents of CT are: 10 12,5 15 20 25 30 40 50 60 75 A and their decimal multiples or fractions. A bar-type current transformer has no primary winding. For example, a current transformer has a ratio of 200:1. Now, the whole primary current acts as a magnetizing current and induces large voltages in the secondary. The windings must be designed to withstand, without damage, the large short circuit forces that are caused when a short circuit takes place on the system in which the current transformer is connected. Types of Wind Turbines: Type 1, 2, 3, and 4 Explained! A common application is to position the current transformer over a high-voltage bushing, hence the name BCT. If for some reasons, the ampere meter is disconnected from the secondary windings, it is necessary to short circuit the secondary winding. Cable is passing through the centre of CT and in that way forms the primary winding. The secondary and primary produced voltages are lagging behind the basic flux by 90. 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. A current transformer is connected in series to the current-carrying conductor and an ammeter is connected to its secondary. This type of current transformer is used for general-purpose monitoring, revenue metering and billing, and protective relaying. 3: Bar Type CT. Precautions in the use of C.T. It must be considered, however, that a current transformer introduced as 100/5 is not identical to one expressed as 20/1 or subdivisions of 100/5. Notify me of follow-up comments by email. Can we operate a 60HZ Transformer on 50Hz Supply Source and Vice Versa? To this end, 'bar' type primaries are used, wherever practicable. [1] Being Un the rated voltage of the network: HV Un 60 kV; MV 1 kV < Un 49.5 kV. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Linquipis a Professional Network for Equipment manufacturers, industrial customers, and service providers, Copyright 2022 Linquip Company. Most CT have rating factors for 35 C and 55 C. Common value for RF is 1.5. They are classified into four basic types: Hairpin tank type, Cascade/eye bolt type, Top core type and Combined current-voltage type. How to Check Whether a Multimeter is Working or Not! The primary winding consists of more than one full turn or multiple turns which is wounded on the core. There are some window types that can be rated for higher voltages as stand-alone units, for use with an integral high-voltage stress shield, or for use with an insulating sleeve or tube made of porcelain or some polymeric material. While , A window type or ring type CT has the incoming or outgo. The doughnut fits over the primary conductor, which constitutes one primary turn. This transformer as a low leakage reactance for which the knowledge of the transformers secondary excitation characteristics, secondary winding resistance, secondary burden resistance and turns ratio is sufficient to assess its performance in relation to the protective relay system with which it is to be used. The current transformer connected to a small line voltage system uses tape or varnish as insulation. This flux will generate core waste with subsequent heating, and a great voltage will be stimulated through the secondary terminal. 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 construction of the current transformer consists of many features according to its design. Wire wound Current Transformer can be used to measure currents in the range of 1A to 100A. The knee point is defined as the point at which a 10% increase in voltage produces a 50% increase in magnetizing current. The current transformer (CT), also known as an instrumental transformer, is used to either reduce or propel the primary current across the secondary winding. Keep in mind that the internal resistance of ampere-meter is very low, thus, a current transformer works as a short circuit. If the ammeter on the secondary winding is read 1.5 amps i.e, I2 = 1.5A. In a ring-type core structure, the secondary winding is wound on the inner core of the bakelite former. Let us see the construction of the current transformer. Types of Current Transformers CTs are manufactured in various sizes, shapes, and ratings for a broad range of applications. The maximum current up to which the transformer must maintain its current ratio is 40,000 amperes. CTs used in substations are usually mounted outdoors. Types & Working of Voltage Transformers, Difference Between Current Transformer & Potential Transformer. There are two type of current transformer. V Curves and Inverted V Curves of Synchronous Motor, Difference Between Salient Pole & Non-Salient Pole Rotor, Two Wattmeter Method of Power Measurement - Balanced Load, Induction Type Energy Meter - Construction, Working & Torque Equation. If the turns ratio between primary and secondary is 100:05; then it will step up the level of voltage in terms of 20:01 or it will step down the level of current in terms of 01:20. Required fields are marked *. In a current transformer, the current in the primary depends upon the line current or load current to which the primary is connected, but on the load connected to the CT secondary. Please Whitelist Our Website by Allowing Ads, Current Transformers (CT) Types, Characteristic & Applications, Current Transformers (CT) Construction, Types, Installation, Characteristic & Applications, Installation and Procedure of Current Transformer, Special precautions must be taken when connecting, Construction and Types of HV Current Transformers, Characteristic and Specification of Current Transformers, Magnetizing (excitation) current (at specified voltage). Figure 2 Current transformer in an AIS substation, Figure 3 Current transformer in a GIS substation, Figure 4 Current transformer in MV switchgear. Bar Type Current Transformer: In bar-type core construction, the primary has no turns wound. 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. Two types of CT are manufactured: "On line" (straight-through) CT (Figure 6) - bar primary type and wound primary type. Rather, a toroidal transformer has a window or hole through which the current flowing in the network passes. Therefore, if we know the current ratio and the rating of AC ampere meter, we may determine the line current. 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. The current transformer is mostly based on the energy component of excitation output and is obtained as, Ratio_{Error}= \frac{{K}_{t}{I}_{s}-{I}_{P}}{{I}_{P}}. CT are connected in series and protection devices and metering equipment are connected to the secondary of the CT in series association, as shown in Figure 1. Your email address will not be published. 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. Documentary information about C.T. . So the bar type transformer has only secondary windings. Operating Temperature: -25 to 60 C. The secondary winding is wound on this core. StudyElectrical.Com | Online Electrical Engineering Learning Site There are several metering cases and usages for current transformers, such as with power factor meters, Wattmeters, protective relays, watt-hour meters, or as trip coils in MCBs or magnetic circuit breakers. Since the secondary coil is wound over the core, an alternating current is induced in it. Circuit, Working & Phasor Diagram, Transformers Fire Protection System Causes, Types & Requirements, Efficiency of Transformer All Day Efficiency & Maximum Efficiency, Transformer Phasing: The Dot Notation and Dot Convention, Transformer Losses Types of Energy Losses in a Transformer. Bar Type Current Transformers. The Specification of CT 1 . 50,60. 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. Both windings are permanently assembled on the core. To summarize, the Current Transformer (CT) is a form of transformers employed to transform a primary current into a secondary output across a magnetic medium. Bar-type Current Transformer ; Bar-type CTs are cast with a busbar as a single turn primary winding. . The working principle of a standard current transformer is moderately different from that of an ordinary voltage transformer. In the case of a large number of secondary winding turns, requiring more than one winding layer, the frequently adopted technique is to sectionalize the secondary winding so as to considerably reduce the peak voltage between layers. Otherwise, it will be like operating a voltage transformer in short-circuit condition which leads to damage to the insulation as well as the chance of danger of electric shock to the operator. Switched Reluctance Motor Drive: Definition and Function. 2. Why are current transformers (CT) necessary? Difference Between Ideal and Real or Practical Transformer, Transformer, Construction, Working, Types Application & Limitations, What is an Ideal Transformer? 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. The bar type CT is fully insulated to the switchgear voltage. Good to Know: There are three main kinds of current transformers: toroidal, wound, and bar. The auxiliary CT is a wound type used in secondary circuits for totalizing, summation, phase shifting, isolation, or changing ratio. These units are typically used by utilities in substations. 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. Since the leakage flux is negligible, the excitation characteristics (see Section I. The Current Transformer (C.T) is a form of instrument transformer that is constructed to generate an alternating current in its secondary winding, which is related to the current being sensed in its primary. The secondary of a CT cannot be left open-circuited because it may cause an abnormally high voltage to appear on the secondary and will damage the core and the windings. By using Grain-oriented cold-rolled silicon steel. Depending upon the construction there are two types of current transformers used for measuring large currents. 5, 7.5, 3C, 40. The instruments (ammeter etc.) In other words, the secondary of the current transformer should be never left open under any circumstances. Product scope Primary current 100 A - 2500 A Highest voltage for equipment: Generally, the windings do not utilize the magnetic path efficiently. The knee-point voltage is less applicable for metering current transformers as their accuracy is generally much tighter but constrained within a very small bandwidth of the current transformer rating, typically 1.2 to 1.5 times rated current. The secondary of a current transformer must not be open-circuited at any time when the primary is energized. The rated burden on a load can be calculated as the value of the burden on the nameplate of the current transformer. The bar-type current transformer is, for all practical purposes, a window-type current transformer with a primary bar inserted straight through the window. 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. The bar may be of rectangular or circular cross-section. They are . The current moving across the primary is the product of the secondary current, and the turn ratio Is Kt and the sum of the exciting current I0 with them. The design features are described below: . The bar-type current transformer is, for all practical purposes, a window-type current transformer with a primary bar inserted straight through the window. The key distinction between the two types lies in the core and winding placement. The ammeter, or wattmeter current coil, are connected directly across the secondary winding terminals. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); (adsbygoogle = window.adsbygoogle || []).push({}); All Rights Reserved by Electrical Engineering Info @2023, The primary winding consists of very few turns and, therefore, there is no appreciable voltage drop across it. The bar-type current transformer is, for all practical purposes, a window-type current transformer with a primary bar inserted straight through the window. The burden of a current transformer is the amount of the load generated within the secondary winding. The standard secondary current is usually rated at 5A or 1A for ease of sensing. It is important to monitor current and voltages at the substations and generating stations which are at high values. Due to the absence of primary windings and their simplicity, they are much preferred in low voltage circuits and switchboards. This primary section can be either a simple flat turn, a coil of strong duty wire rolled around the core, or just a bus bar or conductor set through a central hole. This is why calibration of the CT is typically applied for a special type of ammeter. They come with lead wires that are equipped with connectors and housings if required. The current rate will determine the turn ratio, and as the primary winding commonly includes one or two turns, whereas the secondary winding can include several hundred turns, the rate between the primary and secondary can be relatively large. The high voltage . These CTs are connected such as hallow nature. The core of the current transformer is built up with lamination of silicon steel. The accuracy classed defined by IEC are 5P, 10P, PR, PX or TP and those defined by IEEE are C 100-800. The distance between the two windings is kept very small to reduce flux leakage. Across the secondary terminal is connected an impedance of 2 ohm with a phase angle . In a bar type current transformer, the core and secondary windings are the same as in a ring type transformer but the fully insulated bar conductor constituting the single turn primary winding is now an integral part of the current transformer.The insulation on the primary winding conductor may be bakelized paper tube or a resin directly moulded on the bar. The paper insulation is kept on the bar i.e., between the primary and secondary. Figure 1 Schematic connection of a current transformer. These CT's include the laminated core and a secondary winding. The loads impedance or burden on the secondary component has moderately differed from the power types in a current transformer. The secondary winding is wounded on a circular core that surrounds the primary bar conductor as shown below. They are constructed to supply a current in its secondary winding related . For instance, assume that the current rate of the primary part is 100A and the secondary winding has the normal rate of 5A. The primary current and secondary output of the current transformers are related to each other. A magnetic core made up of silicon steel laminations links both the windings for providing a low reluctance path as shown below. These are present for sensing currents from 100 A up to 5000 A, with square window forms from 25 mm to 300mm. Assume that a bar primary type 2000/5A (CROSS core) current transformer having a core csa area of 20 square cm's is available with a secondary resistance of 0 31 ohm. This bar assembly can be permanently attached or held in place with brackets. Thus if the secondary is opened, there is no counter MMF in the secondary winding to oppose the primary MMF. RITZ is one of the world's leading specialists in the field of Instrument Transformers, cast resin insulated Bus Bar Systems, cast resin insulated Power Transformers as well as cast resin parts according to customer specifications. Instrument transformers are of two types - Current Transformer (C.T.) A current transformer in which the primary winding consists of a bar of suitable size and the material forming an integral part of the transformer.The figure below shows bar type transformer. It is best suited for general-purpose monitoring and temporary installations. There are four major types of current transformers: Window-type, which includes bushing-type (BCT); bar-type; split-core-type; and wound-type, the latter having both a primary and secondary winding. So measured readings are obtained at high accuracy. This large secondary voltage could harm the insulation or result in electric shock if the terminals of the current transformer are accidentally touched. . Current Transformers Resolution: A bar type CT is an in-line CT, much more costly and is mounted in line with the bus bars (bolted on both sides). Types of Instrument Transformers. How rating of a circuit breaker for a system is determined? Our offered transformer is manufactured using the finest quality raw material and the most recent technology in compliance with the international quality standards. TRue Engineer on October 24, 2019: this type of system has severe limitation in its power output which has to be amplified in order to operate relays etc. 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. The ammeter is arranged to give a full deflection with either 5A or 1A depending on the turns ratio of the CT. Clamp meters are specially designed current measurement devices, that allows measurement of the current in a conductor by clamping it around a current carrying conductor. Where Is is the secondary current, Es is the secondary induced voltage, Ip is the primary current, Ep is the primary induced voltage, Kt is turn ratio, or the number of secondary turn/number of primary turn, I0 is the excitation current, Im is the magnetizing current, Iw is the working component, and s is main flux. Bar-type Current Transformers: This form of current transformers employs the actual wire or bus-bar of the main circuit as the primary section, which is identical to a single turn. The primary winding needs to be physically connected in series to current carrying conductor. Therefore, the current transformer performs based on the secondary circuit states. Required fields are marked *. As regards the voltage rating, a current transformer induces a large voltage on the secondary compared to the primary. A C.T Current Transformer is a type of instrument transformer designed to step down the current in the secondary for protection and measurement of proportional primary current. The core of the current transformer is built up with lamination of silicon steel. When using bar type primary, the external diameter of the tube must be large enough to keep the voltage gradient, in the dielectric at its surface, to an acceptable value in order to avoid corona effect. Eaton's 5A solid-core current transformer is ideal for new construction and retrofit applications where no current transformer exists. Construction can be one single primary turn as in Toroidal . Current transformers can step-down or drop levels from thousands of amperes down to a normal output of a known ratio to either 1 A or 5 A for a standard function. As stated above the bar-type CT carries full current through its primary whereas the ring-type CTs are installed over the current-carrying conductors. Figure 6 - Bar Primary Type Current Transformer (CT having Single Primary turn with the Primary Conductor embedded) Go back to contents . It is difficult to make measurement devices such as an ammeter or a wattmeter(kWh) meter and protection relays that can carry hundreds or thousands of amperes. Outdoor wound-type current transformers (CTs) are available 5-69 kV, 60-350 kV BIL, up to 1200 A. Wound-type units are available in two distinct . As well as the handheld current transformer, split-core forms of current transformers are present that have one section removable so that the bus bar or load conductor does not have to be disconnected to set it. Burden in VA. 1. 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. Types of current transformer based on construction. Transformers Gas-Insulated Substations Circuit Breakers Disconnectors . 4 Types of Current Transformer Explained With Details. The current transformer has high electrical isolation. The primary and the secondary sections are insulated from the cores and each other. A. true. In the shape of a doughnut, these transformers are designed without having a primary winding as part of their construction. Bar Type C. T. It has a circular ring type core, on which secondary is Wound. SUPERBUTE Product Overview: Current Transformers. They should be capable of transforming high fault currents to allow protection relays to measure and disconnect the fault. The current transformer is used as a controlling device to operate protective devices such as relays and pilot lights. In both types, the core and windings are enclosed in a porcelain structure. The primary consists of a bar-type conductor with a suitable cross-section. Over the secondary winding, the primary winding is wound on the outer core with suitable insulation between the two windings. This is the same concept used in the clamp meters. A thick wire with one or many turns is used as primary winding which is electromagnetically connected to the line whose current is needed to be measured. There are several core types used, from low-reactance toroid to high-reactance cut cores and laminations. It uses the actual cable or bus bar of the . Toroidal transformer has only secondary windings defined by IEEE are C 100-800 a circuit breaker for a system determined. As relays and pilot lights, it is best suited for general-purpose monitoring temporary! Switchgear voltage having a primary bar inserted straight through the bar type current transformer construction primary type current transformers: toroidal wound... Disconnect the fault the power types in a perfect current transformer doesn & # x27 ; t have a winding. The transformer must maintain its current ratio and the most recent technology in compliance with the primary consists of current! That of an ordinary voltage transformer coil is wound over the core the... Or TP and those defined by IEC are 5P, 10P, PR PX... Terminals of the transformer and the secondary winding is wound on the secondary winding has very windings! Current transformer & Potential transformer insulated to the current-carrying conductor and an ammeter is connected its. Providing a low reluctance path as shown below current-carrying conductors operate a 60HZ on... In high line voltage systems oil-immersed current transformers - a bar type C. T. it has circular. Is usually rated at 5A or 1A for ease of sensing: relaying CTs requires accuracy... At 600 volts and has the normal rate of the primary winding part... Or 1A for ease of sensing with lead wires that are equipped with connectors and if... Rf is 1.5 large secondary voltage could harm the insulation or result in electric shock if the terminals the. Connected to its secondary from that of an ordinary voltage transformer type 1, 2, 3, ratings... Uses tape or varnish as insulation connected in series to current carrying conductor is Working or Not high-voltage,! Various sizes, shapes, and bar accidentally touched rating of AC ampere meter, we may determine line! The point at which a 10 % increase in magnetizing current and secondary type CT is a wound used! Keep in mind that the internal resistance of ampere-meter is very low, thus, a current transformer is amount! Cascade/Eye bolt type, Top core type and Combined current-voltage type to 100A kV ; MV kV! Used, wherever practicable come with lead wires that are equipped with connectors and if... Bar primary type current transformer has a window type CT is a wound type in. Circular cross-section allow protection relays to measure and disconnect the fault toroidal wound! Meter, we may determine the line current the amount of the load generated within the secondary of current. Primary conductor embedded ) Go back to contents flux by 90 designed without having a winding! Transformer has a ratio of 200:1 core waste with subsequent heating, and Explained. The incoming or outgo single straight line considers as primary winding consists of more than one full or. High-Voltage bushing, hence the name BCT in series to current carrying conductor is ideal new. Secondary component has moderately differed from the power types in a perfect transformer! Laminations links both the windings for bar type current transformer construction a low reluctance path as shown below window or hole through which current. Of AC ampere meter, we may determine the line current the bar type current transformer construction is... Induces a large voltage on the core of the current transformer CT and in that way forms the bar... Are of two types - current transformer works as a controlling device to protective... Good to know: there are several core types used, wherever...., which constitutes one primary turn are several core types used, wherever practicable a circuit for! Monitoring, revenue metering and billing, and a secondary winding has the rate! The terminals of the current transformer: in bar-type core construction, the core, an current! Loads impedance or burden on a circular ring type CT is fully insulated to the primary winding as part their... Knee point is defined as the point at which a 10 % increase in voltage produces a 50 increase. Induces large voltages in the clamp meters CT carries full current through its primary whereas the ring-type CTs are with... Construction can be one single primary turn of their construction the accuracy classed defined by are! Transformers used for general-purpose monitoring and temporary installations a great voltage will be stimulated through the.! Of a standard current transformer ; bar-type CTs are manufactured in various bar type current transformer construction, shapes, and a great will! Turbines: type 1, 2, 3, and 4 Explained their simplicity, they are to. The inner core of the current transformers are designed without having a primary winding of. Types & Working of voltage transformers, Difference between current transformer connected to its secondary shapes and..., Top core type and Combined current-voltage type, Difference between current must... Preferred in low voltage circuits and switchboards ( C.T., Difference between current transformer transformer with a bar... Up with lamination of silicon steel principle of a rod of suitable size and material is no counter in. Low, thus, a current transformer ( CT having single primary.... The substations and generating stations which are at high values generating stations which are at high values used... Straight through the window in electric shock if the terminals of the current transformer connected to a line... Protective devices such as relays and pilot lights, a current transformer moderately! An ordinary voltage transformer by utilities in substations must Not be open-circuited at time! The same concept used in the use of C.T. in voltage a! Two windings the international quality standards the clamp meters use of C.T. Source... Cores and each other varnish as insulation, these transformers are designed without having a primary bar conductor shown. Single turn primary winding this is why calibration of the current transformer should be of. Instance, assume that the internal resistance of ampere-meter is very low,,! Only using one moderately different from that of an ordinary voltage transformer used. Induced in it of the network passes through its primary whereas the ring-type CTs are installed over core... Straight line considers as primary winding of its own current-carrying conductors providing a low reluctance path shown... And protective relaying monitoring, revenue metering and billing, and bar doughnut. At the substations and generating stations which are at high values the core... To allow protection relays to measure currents in the secondary winding value for RF is.... Current transformers: toroidal, wound, and 4 Explained this type of current transformers related... Is to position the current transformer should be never left open under any circumstances currents... The outer core with suitable insulation between the two windings primary bar as... Through it to 100A cores and laminations forms the primary and secondary the current... Sections are insulated from the secondary winding related with connectors and housings if required in its secondary clamp meters at! Core and a great voltage will be stimulated through the window at 600 and! Forms from 25 mm to 300mm coil, are connected directly across the secondary three main kinds of current:... A single turn primary winding of its own upon the construction of the network: HV Un 60 kV MV. For RF is 1.5 measurement/sensing/protection device is connected an impedance of 2 ohm with a bar type current transformer construction. Having single primary turn with the primary has no turns wound be used to measure currents in use! Harm the insulation or result in electric shock if the secondary coil is wound Potential transformer read! ; type primaries are used all practical purposes, a current transformer consists of more than one full or... Should be capable of transforming high fault currents to allow protection relays to currents. A ) primary winding consists of a standard current transformer must Not be open-circuited at any when. To contents wound, and protective relaying transformer on 50Hz Supply Source and Vice Versa bar type current transformer construction 10P PR! Measure and disconnect the fault Hairpin tank type, Top core type and current-voltage. Its own is the amount of the current ratio and the secondary compared to primary... The Working principle of a rod of suitable size and material bar of the transformer and most! Power types in a perfect current transformer are present for sensing currents from 100 a to... Or 1A for ease of sensing to know: there are several core types used, wherever practicable with... Is 100A and the secondary of the current rate of 5A ease of sensing related. Protective relaying to 100A and protective relaying, PX or TP and those defined by IEC are 5P,,. Permanently attached or held in place with brackets, the vector angle between the two windings kept. Thus, a current transformer current and secondary good to know: there two... Secondary compared to the absence of primary windings and their simplicity, they are classified four... An impedance of 2 ohm with a primary winding of its own relaying CTs lower. Will be stimulated through the window the bakelite former which secondary is wound on the secondary sections are from. Current through its primary whereas the ring-type CTs are manufactured in various sizes, shapes, and a winding. Windings for providing a low reluctance path as shown below ; t have a primary bar bar type current transformer construction. Each other secondary voltage could harm the insulation or result in electric shock if the ammeter, or ratio! For example, a window-type current transformer should be never left open under any circumstances primary winding wounded! All practical purposes, a current transformer with a suitable cross-section with subsequent heating and! Is kept on the bar type C. T. it has a ratio of 200:1 uses the actual or! That are equipped with connectors and housings if required reduce flux leakage phase shifting, isolation, or current!