One of the most common uses of current transformers are in metering and power usage, where a 5 amp second ary current transformer is applied to a panel. Metering accuracy cts are rated for specified standard burdens and designed to be highly accurate from very low current to the maximum current rating of the ct. Ecostruxure lets you thrive in todays digital world. Providing accurate measurement of the energy consumption of commercial buildings, industrial plants and residential housing is the basis for billing by utility companies. Instrument transformers will transmit the signal to the metering and protective relaying instrumentation, with the purpose of protection of important equipment. Ansi metering current transformer burden e l t e l s c r o l l j u n e tel. For this purpose they must supply a secondary current proportional to the primary current flowing through them and must be adapted to network characteristics. Make better business decisions with scalable and converged itot solutions. The scale of the instrument according to the ct ratio, then becomes the only nonstandard feature of. A fault current is 10 times more than the usual full load curren. Eaton s bline series current transformer metering product line includes ct rated meter sockets, ct enclosures, ct mounting bases, combination ct enclosure meter sockets, test switches and transockets that are designed to meet customers needs in a variety of applications, and are suited for many utility specifications.
Instrument transformers will operate successfully under many atmospheric conditions and transients, and switching overvoltages. A current transformer isolates the measuring instruments from what may be very high voltage in the monitored circuit. Oct 05, 2016 metering current transformers are designed to be within quite accurate values up to say two x rated current, and down to metering current transformer will get a heavily saturated waveform during fault conditions and it wont work properly. The transformer tanks and expansion chambers are manufacturered from mild. Current transformer cabinet free standing overhead to underground service figure. Metering current transformers instrument transformers limited. Ensure the ct is connected to system properly in all respect primary and secondary. Utilitycurrent transformer metering platt electric supply.
Extended range outdoor metering current transformer. 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. Metering current transformers are designed to be within quite accurate values up to say two x rated current, and down 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. While the latter configuration would not be used today, one may be required to make this calculation on an existing system. For this purpose they must supply a secondary current proportional to the primary current flowing through them and must be adapted to. Specifications for commercial underground current transformer metering requirements for a single threephase customer served from a new undergroundpadmount transformer items marked with are indicated on drawing no. December 2019 use only for doing work with or for hydro one 1. Supreme accuracy current transformer super accuracy for 0. Isolate the instruments from the power circuits, standardise the instruments, usually at 5 amps or 1 amp. Current transformer cabinets overhead or underground, service window type cts and pts 277480 volt figure 12. You can also use our live chat tool to speak directly with a sales representative.
Utilitycurrent transformer metering utility enclosures 7 utilitycurrent transformer metering type 3r construction for connected motor loads up to and including 60 horsepower at 480 volts 24h x 14w x 10d hinged viewing window includes brackets for pole mounting aw hub provision 34 inch plywood backboard. The new current transformer and metering speci cations like the iec618692 table above now require accuracies from 0. Itec cto current transformers utilize high permeability, grain oriented silicon steel cores designed to optimize the performance and physical size of the transformer. Current transformers are commonly used in metering and protective relays in the electrical power industry. When extremely accurate measurement is required, or when revenue is generated from a power meter, ansi class current transformers are generally selected. Current sensing for energy metering analog devices.
Utilitycurrent transformer metering 400800 amp50k aicbussed current transformer mounting base 7 utilitycurrent t ransformer metering application ul 414 listed, complies with ansi c12. Whereas the basic purpose of the protection ct is to provide protection in case of any fault. Engineering service specifications commercial threephase. Current transformers technical datasheet schneider electric is the global specialist in energy management with the most complete power monitoring product line. It does so in a predictable and proportionate way, allowing for the accurate measurement of the total current to be deduced from. Ideal for use in cogeneration and in applications where there are large power exchanges, the unit preserves stated accuracies with loads ranging from. Can i use same current transformer for metering and. Medium voltage instrument transformers ritz instrument.
The current sensing requirement is a more difficult problem. A metering ct carries the full load current and are designed near the saturation point. It is not always satisfactory for revenue and precision metering. The metering transformer reduces the current to a level that those instruments can safely handle. This protects connected metering devices from overloading in the presence of fault level current flows. Metering current transformers instrument transformers. Providing accurate measurement of the energy consumption of commercial buildings, industrial plants and residential housing is.
Ge is an industry leader in the design and manufacturing of high, medium and low voltage instrument transformers. If the secondary circuit is closed, a current will flow through the secondary circuit in proportion to the ct ratio. The portfolio of instrument transformers ranges from low voltage at 600 v suitable for industrial and high accuracy revenue metering, all the way up to high voltage at 1,200 kv. Queensland electricity metering manual check this is the latest version before use. Current transformers reduce high voltage currents to a much lower value and provide a convenient way of safely monitoring the. Tape wound measuring and protection current transformers. The transformation from primary to secondary current requires a small amount of energy to. It does so in a predictable and proportionate way, allowing for the accurate. Current transformers splitcore, solidcore flexcore. The kor20er extended range outdoor current transformer is designed for metering outdoor 34. Selecting ansi class metering current transformers cr magnetics. Specifications for commercial underground current transformer metering requirements for a single threephase customer served from a new underground padmount transformer items marked with are indicated on drawing no. Below is a list of all current transformers available through flexcore, however, not all models are instock.
Current transformers play an important role in the monitoring and protection of electrical power systems. Kor ansi outdoor meteringprotection current transformer medium voltage 534. On subtractive polarity transformers the h1 primary lead and the x1 secondary lead will be on the same. The magnetized iron core induces a voltage in the secondary coils. The iron core inside the transformer is magnetized. If you require more information on measuring class, please refer to our guide pdf. With more than 100 years of experience, ge offers a broad array of standard and high accuracy models for revenue metering and system protection applications. A metering transformer, also known as an instrument transformer, can be used where the circuit current is too high to deploy measuring or metering instruments directly. The transformation from primary to secondary current requires a. Suppose one current transformer has rating 1001 a and isf is 1. 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. Choosing your standard industrial current transformer. The circuit influence on the transformer stops as soon as the operating conditions come back to normal. Reach out to our customer team in your country or region if you have any.
To confirm the physical condition and electrical characteristics of current transformer installed in the installation. Mounting base stud locations accepts 6019xx series c. Current transformers are essential components designed to be used with schneider electrics extensive power monitoring product portfolio. 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. The basics of current transformers nk technologies. Utilitycurrent transformer metering cooper industries. The task, consisting of identifying and rating the current transformers and associating them with the protection andor metering units, has always. The following table describes the characteristics of the ansi class transformer. Metering current transformers cts are used with the measuring instruments, such as ammeters, voltmeters, kilowatthour meters, etc to. What is the difference between metering and protection ct. Ideal for use in cogeneration and in applications where there are large power exchanges, the unit preserves stated accuracies with loads ranging from one percent of the full rated current through the rating factor. Energy metering using potential and current transformers energy metering is one of the critical functionalities of todays metering devices. Current transformers are used to supply information to the protective relays andor current, power and energy metering instruments. Current transformer metering ct metering overview b.
Data sent by current transformers are processed by protection, control and monitoring units that send signals to operate switchgear andor information to a supervisory unit or to a central control room. We have over 40 years of experience with manufacturing metering current transformers of various specifications for customers all over the globe. Energy metering using potential and current transformers. These have to be very carefully filtered and amplified to keep the meters specified accuracy in the low current level. The 3in1 current transformer range are for use with the integra dl1 digital metering. 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 new eq meter series complete abb offer of measurement devices for fiscal and billing applications since they are provid ed with terminals cover and. Kor ansi outdoor meteringprotection current transformer. Current transformer basics and the current transformer. Instrument transformer basic technical information and. Eatons bline series current transformer metering product line includes ct rated meter sockets, ct enclosures, ct mounting bases, combination ct enclosure meter sockets, test switches and transockets that are designed to meet customers needs in a variety of applications, and are suited for many utility specifications. Current transformers and power line transformers for smart metering. That means, in first current transformer, the metering core would be saturated at 1.
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