When the currents in a number of feeders need not be individually metered but summated to a single meter or instrument, a summation current transformer can be. Hobut ctm100 summation current transformer range with 5a output ctm1002x5551 hobut ctm100s can be supplied exstock at camax uk ltd 3 required for three phase systems 1 per phase. Each of the above methods has been explained in depth in the following sessions along with their pros cons and limitations. 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. Ts are designed to summarize several synchronous a. Summation current transformer is used when the currents in a number of feeders dont need to be individually metered but summated to a single meter or instrument. The terminals of the transformers are protected by a cover. The current transformer can be supplied as a resin cast version or in a plastic box. The primary of the current transformers is directly connected in series with the line conductor that carries the entire. The pulsing meters, pulse summation unit and demand recorder. A current transformer operates with a set primary current and will try to output a constant current to the load, independent of the load. Summation current transformers are designed to sum up secondary currents of a number of mains cts. On subtractive polarity transformers the h1 primary lead and the x1 secondary lead will be on the same. Each summing transformer must be connected to one phase only.
Electricals suppliers of resin cast summation type cts, summation ct manufacturer, summation current transformer manufacturing companies in maharashtra. Part of deifs current transformer range, the summation transformers summarise the secondary currents of up to 8 main current transformers to a common secondary. If the current measurement is carried out with two or more current transformers e. Current summations with current transformers ieee xplore. Current transformers,voltage transformers and instrument. Electricals suppliers of tape wound current transformer, summation current transformer manufacturer, ring type resin cast current transformer manufacturing companies in maharashtra. Electrical current transformers,summation current transformer. The introduction of digital technology has led to further improvements in bus differential. Transformer theory quiz questions electrician practice tests. That point on the magnetizing curve where an increase of 10% in the flux density voltage causes an increase of 50% in the magnetizing force current.
The current transformer function is different than that of a voltage transformer. In order to facilitate the user in making the right selection of components of a measurement setup with summation current transformers, the following examples have been listed. The housing of the transformers is made of impactresistant thermoplastic to ensure a highly reliable quality. The summation transformers are used for comparing the relaying quantities derived from the current in the three phases of the primary circuit. The transformer must not be shortcircuit connected. Thus, in an ideal transformer the power ratio is equal to one unity as the voltage, v multiplied by. Testing setup for a 3circuit summation transformer equipment, with line. The basics of current transformers nk technologies. If a ct test switch is used, the switch must have a makebeforebreak contact pattern to. Jul, 2018 free electrical calculator for android best android app for electrical engineer and eee student how to get electrical license in tamil. Unused primary connections have to be open circuited as opposed to the short circuiting of secondary connections. Pfiffner instrument transformers ltd pfiffner instrument transformers ltd. Hobut ctm100 summation current transformer range with 5a.
The summation ct consists of two or more primary windings which are connected to the feeders to be summated, and a single secondary winding, which feeds a current proportional to the summated primary current. Once the, indicator uses a summation current transformer instead of the shortcircuit current transformer for l2, summation current transformer for mounting on cables 496016 620 earth fault current, summation current transformer or more specifically three singlephase current transformers, and a. Electricals offering summation current transformer. Pfiffner deutschland gmbh pfiffner india pfiffner systems ltd. Summation current transformer definition and meaning. Summation current transformer metering class sensor 66. Contents hide 1 different types of current transformers. The following texts are the property of their respective authors and we thank them for giving us the opportunity to share for free to students, teachers and users of the web their texts will used only for illustrative educational and scientific purposes only. Transformer theory quiz questions free online quiz test transformer theory and practice. If a summation current transformer possesses an unused primary circuit for the eventual connection of an further main transformer, then this circuit must remain open. Summation current transformers are suitable for the summation of several. A transformer has no moving parts and is a completely. Summation current transformer for core current transformers. Technical data dimension diagrams summation current transformer.
This transformer is mainly employed for the unbalanced condition in the system and due to fault condition so that the relay operates properly. This behaviour is the case with current transformers within the allowable load range and below a few thousand hertz. It can be designed to step up or step down voltages and works on the magnetic induction principle. Part of deifs current transformer range, the summation transformers summarise the secondary currents of up to 8 main current transformers to a common secondary signal. Summation cts summation current transformers allow several independent circuits to summate into one meter. Guidance when ordering summation current transformers. The secondary connections of each main transformer are connected to the allocated primary inputs of the summation current transformers. Sep 07, 2016 current transformer ct working principle, how an electrical current transformer works, uses, types, load resistor concept is explained in the video lecture by industry person. 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.
Allentown, pa abstract more and more substations are retrofitted with numerical relays, meters and monitoring devices. This is the first part of video series called as current transformer in this video i have discussed about definition of current transformer and working principle of it. Scribd is the worlds largest social reading and publishing site. The transformer which is used for converting the threephase quantities into the single phase quantity is known as the summation transformer. In consumer installation, where there is more than one feeder, it is more economical to use summation metering and for this purpose, summation current transformer ct is required. Current sensors current transformers opto current transformers external signal lamps wallmounted housings other accessories for shortcircuit and earth fault indicators accessories for overhead line faulted circuit indicators solutions for remote monitoring.
The current transformer will operate into either a short circuit or a resistive load until the voltage induced is enough to. 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. In an ideal transformer ignoring any losses, the power available in the secondary winding will be the same as the power in the primary winding, they are constant wattage devices and do not change the power only the voltage to current ratio. Summation ct transformer electrical components scribd. Hobut ctm100 summation current transformer range with 5a output ctm1002x5551. The numbers of mains cts to be totaled may ranged from 2 to 6 and are available for 1a or 5a secondary current ratings. Summation current transformer,summation ct manufacturers. When the current in a number of feeders need not be individually metered but summated to a single meter or instrument, a summation current transformer can be used.
A transformer is an electrical apparatus designed to convert alternating current from one voltage to another. Morgan lacey in 1925, based on a series of pamphlets entitled transformer abstracts that were. The digital value summation metering units using microprocessor. The use of current transformers to sum the currents in a number of. The output of the summing transformer is connected to the input of a wt series watt transducer. The secondary connections of each main transformer are connected to the allocated. If a summation current transformer possesses an unused primary circuit for the eventual connection of an further main transformer, then this circuit must remain. Summation current transformers summation cts from itlmanufactured to iec standards and designed with multiple inputs and a single secondary output e. Transformer book is still in demand is a tribute to the publishers and to the authors who have carried the torch to light our way for 75 years. As long as the current to be measured are small and at low voltage, the direct method of connecting the instruments and relays in the circuits is convenient and adequate. The essentials of current transformers in power circuits. Typically the ct ratios must be the same, but different ratios can be used with a specially built summing transformer.