Schneider electric is the global specialist in energy management with the most complete power. A true bar type current transformer is a toroidal type transformer with a bus bar as an integral part of the current transformer which is permanently inserted through the window of the torroid. Low voltage current transformer low voltage current transformer general reference standards iec600441, vde0414441, din57414, bs3938, bs7626, en600441, gb12082009 measuring current transformers are constructed to feed on other low voltage apparatus such as measuring instruments, relays, watthour meters kw meter and these type of current. Basics, maintenance, and diagnostics vii contents continued page 4.
Another very common type of construction is the socalled window, through or donut type current transformer in which the core has an opening through which. Transformer with the primary current be turned twice which help to keep the samerated turns ratio1. To confirm the physical condition and electrical characteristics of current transformer installed in the installation. These transformers provide insulation against the high voltage of the power circuit, and also supply the relays with quantities proportional to those of the. Current transformers, along with voltage or potential transformers, are instrument transformers. The current transformer can be used in commercial grade applications. Like the power transformer, the current transformer also contains a primary and a secondary winding. Indooroutdoor current transformer elk cn3 instrument. Current transformers 99 protective relays of the ac type are actuated by current and voltage supplied by current and voltage transformers. The primary of the current transformers is considered as the line or cable or busbar of the load circuit. 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 centers.
Instead, the line that carries the current flowing in the network is threaded through a window or hole in the toroidal transformer. Abb library is a web tool for searching for documents related to abb products and services. It is even possible to install this type of transformer while the conductor is energized. For the encapsulated type current transformer, the windings are enclosed in a. At 5% rated current through 100%, the current transformer must maintain 0. They are fully insulated from the high operating voltage of the system and are usually bolted to the currentcarrying device. Current transformers, model 186 current transformer simpson. The kneepoint 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.
Pa current transformers are filled with pcbfree transformer oil. The various types of transformer shown in the figure above are explained in detail below. They are very popular in submetering applications where existing systems are being upgraded and it is impractical to isolate the primary conductor. The polarity marks of a current transformer indicate that when a primary current enters at the polarity mark h1 of the primary, a current in. The basics of current transformers nk technologies. Allentown, pa abstract more and more substations are retrofitted with numerical relays. Traditional, window type current transformers for measuring 50400hz currents of 5a to 15000a with secondaries of 0. Abb oem instrument transformer reference guide april 2014. A current transformer is an instrument transformer in which the current ratio is within the specified limit. The classification of protection current transformers follows the. Bartype current transformer this type of current transformer uses the actual cable or busbar of the main circuit as the primary winding, which is equivalent to a single turn. Whenever an alternating current flows through the primary winding, alternating magnetic flux is produced, which then induces alternating current in the. A bartype 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.
Current transformer white paper the basics of current transformers ratio the ct ratio is the ratio of primary current input to secondary current output at full load. This type of transformer is categorized on the basis of a number of turns in. Another very common type of construction is the socalled window, through or donut type current transformer in which the core has an opening through which the conductor carrying the primary load current is passed. This type of current transformer is available to measure ac currents from 100a to 600a, at 50 to 400hz. Wound cts have a primary and secondary winding like a normal transformer. Transformers used for voltage potential measurement steps down. If the primary current changes, the secondary current output will change accordingly. These transformers provide insulation against the high. This type of ct often has compensating windings which improve the accuracy across the full load range of the transformer. May 2014 type imc current transformer 600 volt, 10 kv bil, indoor. They transform high current into stan dardised values for meters. When current flow exceeds that rating, the metering core will become saturated, thereby limiting the amount of current level within the device.
A current transformer can also be used as an input to a current relay or transmitter, or to reduce the current so that a current switch or transducer can be utilized. Different types of transformers and their applications. The primary current of minimum of 25% rated primary. Protection current transformers are constructed to feed the protection relay. Tropicalized for cable or bar current transformer t1. Current transformers are essential components designed to be used with. 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. Used in ac system for the measurement of current, voltage, power and energy. Perfect for low current measurement where a donut current transformer would not sense a signal download datasheet. The pa current transformers are used in electric power grids with system voltage of up to 145 kv and frequency of 50 hz. Transformers used for voltage potential measurement steps down the voltage to the level of voltmeter. They are very popular in submetering applications where existing systems are being upgraded and it.
The ratio of a current transformer is equivalent to the voltage ratio of potential transformers. Current transformer ct construction and working principle. Current transformer basics and the current transformer. The circuit connection shall be made as shown figure 4. The classification of protection current transformers follows the following. The secondary of the current transformer is portable. Outdoorrated versions of this equipment are used in pole mounted primary metering installations. Simply short the secondary of the ct through the sensing window of the sensor. Bartype current transformer this type of current transformer uses the actual cable or busbar of the main circuit as the primary winding, which. Turns ratio tests optional test this test is to ensure the turns ratio of ct at all taps. The secondary winding of current transformer which will not be used must always be shortcircuited and earthed as seen in figure2. Secondary winding of a current transformer must not be operated with an open circuit. Current transformers pfiffner instrument transformers ltd. Most often, the older relay gets replaced with a newer relay with the rest of the installation such as current transformer ct and lead.
It buffers the meter from experiencing excessive torques that might be. 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. They are designed using top core current transformer construction. Browse our products in tropicalized for cable or bar for current transformer t1 current transformers from 40a to 6000a. Types kotd110, 150, and 200 current transformers medium voltage. Here we discuss different types of transformers are the step up and step down transformer, distribution transformer, potential transformer, power transformer, 1. The x1 secondary terminal is the polarity terminal figure 3.
Types of transformer different types of transformer. This protects connected metering devices from overloading in the presence of fault level current flows. Current transformers windings and rated insulation levels. Introduction generally a transformer is an electrical device or machine which inductively transfers the electrical power operating at a particular current and voltage of one circuit to the other. Abb library is a web tool for searching for documents related to abb products. Standard current transformer multiratio taps 214 burden standards 214 5 kv 36 kv indoor voltage transformers primary current class abb type geiti equivalent abb product bulletin page 2400 to 4800 5 kv indoor viy60 ptw3160 and ptw3260 1vap429511db 148149 2400 to 72007200 8.
Nov 15, 2019 the basic principle of the current transformer is the same as that of the power transformer. December 2019 type rlc current transformer 600 volt, 10 kv bil, indoor or outdoor. Standard current transformer multiratio taps 214 burden standards 214 5 kv 36 kv indoor voltage transformers primary current class abb type geiti equivalent abb product bulletin page 2400 to. The elk current transformers have a possibility of reconnection on the secondary side.
Ensure the ct is connected to system properly in all respect primary and secondary. Back to the basics current testing valence electrical. Current transformers type pa 123 kv and 145 kv instrument. A true bar type current transformer is a toroidal type transformer with a bus bar as an integral part of the current transformer which is permanently inserted. Eaton s 5a solid core current transformer is ideal for new construction and retrofit applications where no current transformer exists. In thrutype units, busbar and copper tube inside the unit need to be at the same potential. Current transformers type jof are used in high voltage networks within the 24 550 kv range. These are the most commonly used transformer types for all the applications. It produces a current in its secondary which is proportional to the current in its primary. Typically, the single straight line considers as primary winding. Bar type cts operate on the same principle of donut cts but have a permanent bar installed as a primary conductor. Instrument transformer basic technical information and. The primary winding is connected in series with the load and carries the load current to be measured. Current transformers, model 186 current transformer.
Schneider electrics extensive power monitoring product portfolio. Current transformer type elk without primary conductor is designed for installation in sf6 gas insulated switchgear gis indoor or outdoor systems up to 420 kv. It should be connected measuring devices before application of primary connection as seen in figure1. May 2014 type imc current transformer 600 volt, 10 kv bil. Window type cts should be mounted with the h1 side of the window towards the power source. However, the concept of knee point voltage is very pertinent to protection current transformers, since they are necessarily exposed to currents of 20 or. For use with rectifier type analog panel meters or digital indicators. For example, if 150 amps flow through the 300 amp rated primary, the secondary current would be 2. 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. Unsure which of our hobut current transformer range you need.
The basic principle of the current transformer is the same as that of the power transformer. Types kotd110, 150, and 200 current transformers medium voltage instrument transformer nsv 15 kv through 36 kv outdoor primary amperes 4005000 25 through 60 hertz type kotd110110 kv bil. The transformer is a static electric device consisting essentially of two or more windings wound on the same core electromagnetic induction transforms electric energy from one circuit to another circuit such that the frequency of the energy remains unchanged while the voltage and current usually change definition of a transformers. Allentown, pa abstract more and more substations are retrofitted with numerical relays, meters and monitoring devices. The bar type is inserted in the circuit to be monitored. The active elements are located in a hermetic housing inside the head of the transformer. 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. Abb complete and comprehensive range of ct current trans formers is the perfect. This type of transformer is categorized on the basis of a number of turns in the primary and secondary windings and the induced emf.
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