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. In principle, the only difference between a current transformer and a voltage transformer normal type is that the former is fed with a. This protects connected metering devices from overloading in the presence of fault level current flows. Window type cts should be mounted with the h1 side of the window towards the power source. The name instrument transformer is a general classification applied to current and. Wound type ct is similar to the two winding conventional transformer. 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. It is even possible to install this type of transformer while the conductor is energized. Indoor current transformer cable kola current transformers type kola indoor dry type, cast resin insulated are designed for rated voltages up to 0.
Transformers used for voltage potential measurement steps down the voltage to the level of voltmeter. It is used for metering electric energy, current and relay protection of 115kv in electric substaion system and frequency is 50hz or 60hz. Blue sea makes some good products and has a outstanding reputation. The classification of protection current transformers follows the following.
Berry type transformer has more than two independent magnetic circuits i. When current flow exceeds that rating, the metering core will become saturated, thereby limiting the amount of current level within the device. Current transformers are essential components designed to be used with schneider electrics extensive power monitoring product portfolio. The x1 secondary terminal is the polarity terminal figure 3. Most of the transformers are manufactured such that their characteristics must match for special application requirements. They are fully insulated from the high operating voltage of the system and are usually bolted to the currentcarrying device. Nov 15, 2019 the basic principle of the current transformer is the same as that of the power transformer.
The construction of the current transformer can be wound or bar type. Whenever an alternating current flows through the primary winding, alternating magnetic flux is produced, which then induces alternating current in the. Basics, maintenance, and diagnostics vii contents continued page 4. The doughnut fits over the primary conductor, which constitutes one primary turn. To check pricing and availability for a specific current transformer model, give us a call at 614 8896152 or use our quote request form. The basics of current transformers nk technologies. 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. It buffers the meter from experiencing excessive torques that might be. Current transformers, model 186 current transformer simpson electric optimal for remote sensing of ac current signals. Transformer with the primary current be turned twice which help to keep the samerated turns ratio1. Current transformer basics and the current transformer. However, the concept of knee point voltage is very pertinent to protection current transformers, since they are necessarily exposed to currents of 20 or.
Protection current transformers are constructed to feed the protection relay. They are designed using top core current transformer construction. Bartype cts have primary connections that boltup directly to the substation bus bars. A current transformer ct is a type of transformer that is used to reduce or multiply an. To confirm the physical condition and electrical characteristics of current transformer installed in the installation. December 2019 type rlc current transformer 600 volt, 10 kv bil, indoor or outdoor. You can also use our live chat tool to speak directly with a sales representative. Pa current transformers are filled with pcbfree transformer oil. For a low voltage wound type ct, the secondary turns are wound on a bakelite former and with a. Instrument transformer basic technical information and. They are very popular in submetering applications where existing systems are being upgraded and it is impractical to isolate the primary conductor. Like the power transformer, the current transformer also contains a primary and a secondary winding. It is actually a shell type transformer but the name is related to the designer and its cylindrical shape. The active elements are located in a hermetic housing inside the head of the transformer.
The primary of the current transformers is directly connected in series with the line conductor that. The above image is showing the construction of the current transformer. This paper describes the saturation study of current transformer during transient fault. These are the most commonly used transformer types for all the applications. Socomec current transformers deliver a standard current to the secondary that is proportional to the primary. Below is a list of all current transformers available through flexcore, however, not all models are instock. Metering toroidal current transformers traditional, window type current transformers for measuring 50400hz currents of 5a to 15000a with secondaries of 0. The primary winding consists of more than one full turn or multiple turns which is wounded on the core. Here we discuss different types of transformers are the step up and step down transformer, distribution transformer, potential transformer, power transformer, 1. Perfect for low current measurement where a donut current transformer would not sense a signal download datasheet. The major difference between measuring transformers and protection transformers is the accuracy that means that the protection transformers should be accurate as compared to measuring transformers.
This type of current transformer is available to measure ac currents from 100a to 600a, at 50 to 400hz. Ring type current transformer do not contain a primary. This type of ct often has compensating windings which improve the accuracy across the full load range of the transformer. Abb library is a web tool for searching for documents related to abb products. Current transformers 99 protective relays of the ac type are actuated by current and voltage supplied by current and voltage transformers. Current transformers cts can be used for monitoring current or for transforming primary current into reduced. It should be connected measuring devices before application of primary connection as seen in figure1. 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. Msq current transformer technical characteristics of current transformers. May 2014 type imc current transformer 600 volt, 10 kv bil. Bar type cts operate on the same principle of donut cts but have a permanent bar installed as a primary conductor. Determine the usual application of current transformer that best suits the application for which it is intended. Most of the transformers are manufactured such that their characteristics must match for special. The core construction of berry type transformer is like spokes of a wheal.
I purchased this ac current transformer for a power generator wattage meter and it does a great job measuring the wattage of my generator. This makes the replacement of instrument transformer very easy. Types of transformer different types of transformer. Jun 01, 2015 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 circuit which is operating at different current and voltage level. Distribution transformers are step down transformer, which converts high grid voltage to the end customer required voltage, 110v or 230v. With 150 amps through the 300 amp rated primary, the secondary current will be 2. Current transformers, model 186 current transformer simpson. The various types of transformer shown in the figure above are explained in detail below. Oct 08, 2016 in principle, the only difference between a current transformer and a voltage transformer normal type is that the former is fed with a constant currentwhile the latter is fed with a constant voltage, where constant has the strict circuit theory meaning. A measurement type ct of 20005 a, 25va rating is used. Jun 02, 2015 therefore, the current transformer does the current conversion from high currents to a measurable range of currents.
Huayi professional current transformer, voltage transformer, capacitor voltage transformer, transformer, surge arrester manufacturers and suppliers in china, providing the best quality transformer made in china with competitive price. For use with rectifier type analog panel meters or digital indicators. When current flows through the primary winding, the following actions occur. 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. 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. Ring type current transformer is constructed of an iron toroid, which forms the magnetic core of the current transformer, and secondary turns are wound with copper wire. 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. Instrument transformers are used in ac system for measurement of electrical quantities i. This unit can be applied over higher rated system voltages provided sufficient insulation is available on the point of application.
Current transformer ct construction and working principle. The pa current transformers are used in electric power grids with system voltage of up to 145 kv and frequency of 50 hz. April 2019 type csh current transformer 600 volt, 10 kv bil, indoor or outdoor. Current transformers technical datasheet schneider electric is the global specialist in energy management with the most complete power monitoring product line. Back to the basics current testing valence electrical. Current transformers cts are instrument transformers that are used to supply a. 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. Medium voltage current transformers cable type kola are suitable for the measurement of the sum of threephase currents in a. The polarity marks of a current transformer indicate that when a primary current enters. A potential transformer is a conventional transformer having primary and secondary windings. Current transformers ratio polarity types educypedia. The secondary winding of current transformer which will not be used must always be shortcircuited and earthed as seen in figure2. If the application requirements are not fully defined, refer to. For example, the potential transformer mentioned above having a rating of 480.
Ensure the ct is connected to system properly in all respect primary and secondary. Tape wound measuring and protection current transformers. 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. 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. I received the transformer very quickly and it was well package, i highly recommend this product for all your electronic needs. In thrutype units, busbar and copper tube inside the unit need to be at the same potential. The ratio of an instrument transformer is the relationship of its primary rating to its secondary rating. This type of transformers is used in component protection purpose. Bar and donut type cts do not have a physical primary winding and are considered to have one primary turn. The specific application of current transformers involves in various considerations such as type of mechanical construction, ratio of primary to secondary currents, type of insulation oil or dry type, thermal conditions. Perfect for low current measurement where a donut current.
A current transformer is an instrument transformer, used along with measuring or protective devices, in which the secondary current is proportional to the primary current under normal conditions of operation and differs from it by an angle which is approximately zero. Abb library is a web tool for searching for documents related to abb products and services. 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. Current transformers, model 186 current transformer. Different types of transformers and their applications. Typically current transformers consist of a silicon steel ring core wound with many.
Secondary winding of a current transformer must not be operated with an open circuit. Used in ac system for the measurement of current, voltage, power and energy. Wound cts have a primary and secondary winding like a normal transformer. Type psh993 indooroutdoor current transformer instrument transformers and sensors application the psh993 indooroutdoor, windowtype current transformer is a 600 volt, 10 kv bil rated unit. Current transformers type pa 123 kv and 145 kv instrument. China current transformer, voltage transformer, surge. 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 circuit which is operating at different current and voltage level. Current transformers reduce high voltage currents to a much lower value and provide a convenient way of safely monitoring the actual electrical current flowing in an ac. For the encapsulated type current transformer, the windings are enclosed in a. Parts of current transformer like any transformer, a current transformer has a primary winding, a core and a secondary winding, although some transformers, including current transformers, use an air core. Medium voltage current transformers cable type kola are suitable for the measurement of the sum of threephase currents in a 3phase cable.
105 738 1012 450 554 557 123 1052 867 34 1467 932 806 164 1343 1129 1442 1350 1100 151 741 425 542 290 1158 717 547 1249 894 1260 282 1397 636 137 66 1379 676 1424 845