Current transformer continental control systems, llc. The primary of the current transformers is directly connected in series with the line conductor that carries the entire current to be measured. The primary winding can consist merely of the primary current conductor passing once through an aperture in the current transformer core window or bartype, or it may consist of two or more turns wound on the core together with the secondary winding wound type. Instrument transformers are used for measurement and protective application, together with equipment such as meters and relays. Current transformer basics and the current transformer. They are designed for connection linetoline or linetoneutral in the same manner as ordinary voltmeters. Types of transformer different types of transformer circuit globe. Current transformers,voltage transformers and instrument.
It produces a current in its secondary which is proportional to the current in its primary. These are used at very low current ratios such as summing. Current and voltage instrument transformers instruction for. The current transformer will operate into either a short circuit or a resistive load until the. It utilizes the currenttransformation and voltage instrument transformers types of instrument transformers. Current and voltage transformers may be freestanding devices, or they may be built inside the bushing of some power apparatus such as a circuit breaker or a power transformer with a grounded tank. They are designed to present negligible load to the supply being measured and have an accurate voltage ratio and phase relat. We have discussed about the theory of ideal transformer for better understanding of actual elementary theory of transformer. Types of transformer different types of transformer. Current transformers perform the following functions.
A bushing type current transformer usually is used in equipment where the primary conductor is a component pan of other apparatus. Unique to a current transformer the current transformer function is different than that of a voltage transformer. Transformer operates when both circuits take effect of mutual induction. One can find variety of current transformers which is an instrument used for measuring and protecting devices. This type of transformer is categorized on the basis of a number of turns in the primary and secondary windings and the induced emf.
Ac ct alternatingcurrent current transformer ac current transformer alternatingcurrent current transformer air core transformer. These are widely used transformer types for all the applications. Current transformers, along with voltage or potential transformers, are instrument transformers. The second method is to parallel ct inputs at the transducer. 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. Here the important thing to remember is that there will not be any difference in primary power and secondary power.
P1 k, p2 l, s1 k, s2 l continued installation notes. 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 that is approximately zero. A transformer is an electrical device that can be used to transfer the power from one circuit and another circuit without physical contact and without changing its characteristics like frequency, phase. Current transformers schneider electric documentsdownloads. Current transformer consists of either one or few primary winding turns due to which it has also been called as series transformer. There are four typical types of current transformers. Polarity refers to the instantaneous direction of the primary current with respect to the secondary current and is determined by the way the transformer leads are brought out of the case. Continuous thermal current rating factor models 3p3500 3p3301. The basics of current transformers nk technologies. Current transformer type imt imt current transformer is used to supply current circuits in power equipment measuring systems with rated voltage of 0. According to the design, transformers can be classified into two. Current transformer transformer electrical components. Potential transformers used primarily in a step down environment to monitor voltage.
Measurement canada approval, t0285 or ae0320 or ae0312 when choosing your ge instrument transformer, dont forget to explore the benefits of using ges 0. Thirteen of these types are called conventional rubber. Chapter 16 current transformer design wordpress for the. The transformers are built for the primary current range of 75 a a and the secondary current of 5 a. These are generally used for low voltage circuits and further classified into wound type, bar type and window type transformers. Energy is stored in the magnetic field of the transformer when the pulse is applied. Transformer basicsworking principle,construction,types. It is a transformer that is used in conjunction with any measuring instrument i.
However, the concept of knee point voltage is very pertinent to protection current transformers, since they are necessarily exposed to currents of 20 or. This page lists various names used in literature and practical applications. Current transformer design tool assists design engineers in choosing the most appropriate core material and size for a number of current transformer ct topologies. Transformer in which the magnetic circuit completely surrounds the windings explanation of shelltype transformer. Transformers transformer types transformer types transformers can be constructed so that they are designed to perform a specific function.
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. In a transformer, electric current passes through coils of wire wrapped around a magnetically permeable material called a core, where it produces a changing magnetic field in that core. The types of transformers differ in the manner in which the primary and secondary coils are provided around the laminated steel core. That means they are mixed, milled, and molded by techniques which have been in use by the rubber industry since the 1920s. Current transformers principle of operation of ct a current transformer is defined as as an instrument transformer in which the secondary current is substantially proportional to the primary current under normal conditions of operation and differs in phase from it by an angle which is approximately zero for an appropriate direction of the connections. Basics, maintenance, and diagnostics vii contents continued page 4. In addition to your contact information, please include the ccs part numbers that you have and a description of the symptoms and issues. Contact technical support for help troubleshooting problems and technical questions, please send an email to technical support. The imt transformers are dedicated to power balance. A current transformer operates with a set primary current and will try to output a constant current to the load, independent of the load. On subtractive polarity transformers the h1 primary lead and the x1 secondary lead will be on the same. Instrument transformers comprise a large category of current and potential transformers for various voltage. While the latter configuration would not be used today, one may be required to make this calculation on an existing system.
A current transformer ct is a type of transformer that is used to reduce or multiply an alternating current ac. Current transformer sensors are available at mouser electronics. Theory of transformer on load and no load operation. Along with the generators that supply the power grid, transformers are key to power distribution. This type of current transformer is for use with a fully insulated conductor as the primary winding. Here is highlighted few important types of current transformer. Cts current transformers pts potential transformers. Their role in electrical systems is of primary importance as they are a means of stepping down the current or voltage of a system to measurable values, such as 5a or 1a in the case of a current transformers or 110v or 100v in the case of a voltage transformer. Read through the different types we supply below and use our instrument transformer rfq form to request a specific part to meet your requirements. A basic understanding of the various types of transformers is necessary to understand the role transformers play in todays nuclear facilities. A current transformer is a device which produces an alternating current in its secondary which is proportional to the alternating current in its primary. Voltage transformers is also called as potential transformers this is a parallel connected type of instrument transformer.
Transformer only stepup or stepdown the level of ac voltage or ac current. A current transformer is similar to a electrical power transformer to some extent, but there are some difference in construction and operation principle. Traditional, often line frequency current transformers, hall effect current transformers and switchmode power supply smps current transformers are examined in depth. In coretype transformer, the windings are given to a considerable part of the core. Highcurrent transformers pfiffner instrument transformers. Relays are required to perform in fault current type situations moderate accuracy over a wider range more core material is needed metering vs protection classes. Transformer cant stepup or stepdown the level of dc voltage or dc current. Type aka current transformers are usu ally used in encased ducts, socalled iso lated phase bus ducts ibps. The fundamentals of current sense transformer design patrick a. There are three basic types of current transformers. Different types of transformers and their applications. The imt transformers are dedicated to power balance systems which use the current transformer to measure current on the low voltage side of the transformer.
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